Efficient market hypothesis (EMH)

Efficient Market Hypothesis 

• alternatively known as the efficient market theory
• a hypothesis that states that share prices reflect all information and consistent alpha generation is impossible.
• c.f., alpha
• often referred to as “excess return” or “abnormal rate of return

Swing trading

Swing trading

• A style of trading that attempts to capture short- to medium-term gains in a stock (or any financial instrument) over a period of a few days to several weeks
• Primarily use technical analysis to look for trading opportunities. 
• These traders may utilize fundamental analysis in addition to analyzing price trends and patterns
• c.f., technical analysis
• evaluate investments and identify trading opportunities by analyzing statistical trends gathered from trading activity, such as price movement and volume.
• focuses on the study of price and volume. Technical analysis tools are used to scrutinize the ways supply and demand for a security will affect changes in price, volume and implied volatility.
• c.f., fundamental analysis
• The end goal is to arrive at a number that an investor can compare with a security's current price in order to see whether the security is undervalued or overvalued.
• studys anything that can affect the security's value, from macroeconomic factors such as the state of the economy and industry conditions to microeconomic factors like the effectiveness of the company's management.
• For stocks, fundamental analysis uses revenues, earnings, future growth, return on equity, profit margins, and other data to determine a company's underlying value and potential for future growth. 
• All of this data is available in a company's financial statements

Synapse

Synapse

• In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.
• c.f., neuron
• Neurons are the cells that make up the nervous system

Adenosine & caffeine

Adenosine

• Adenosine itself is a neuromodulator and is believed to play a role in promoting sleep and suppressing arousal
• Our body produces adenosine in the brain when fatigue builds up
• Adenosine keeps accumulating while awake
• c.f., Adenosine recepter
• A pressure gauge in the brain that senses sleep pressure
• The more adenosine biomolecule sticks to it (= adenosine recepter), the higher the sleep pressure in the brain feels. 
• Caffeine disturbs the sleep pressure gauge
• Caffeine is a molecule similar in structure to adenosine, so it sticks to the adenosine receptor, but unlike adenosine, the receptor does not recognize it as a fatigue signal.
• Caffeine is only blocking the place where adenosine will attach.
• So, if caffeine accumulates and the receptors are saturated, does the sleep pressure gauge completely fail?
• Because caffeine is a xenobiotic substance, that is, a foreign substance that has entered the body, our body dispatches enzymes to break it down.
• around 5 fours
• The effects of caffeine vary greatly from person to person, that is, from genome to genome.

Baseball positions

Baseball positions

• Shortstop (SS)
• the fielding position between second and third base, which is considered to be among the most demanding defensive positions
• Battery
• refers collectively to the pitcher and the catcher
• Designated hitter (DH)
• a player that bats in place of the pitcher
• c.f., history
• It was in the late 1960s that the designated hitter system began to be discussed in earnest, which was the worst batting average in the history of the major leagues.
• For this reason, the major leagues faced the urgency that the game would become fun if the attack survived somehow, and this became a decisive moment, and the designated hitter system, which did not participate in the defense while hitting the pitcher's attack turn, was introduced into the American League from 1973. 
• c.f., the difference between the National League and the American League
• The American League has a designated hitter system that does not defend and only hits, but there are no designated hitters in the National League.
• Instead, in the National League, the pitcher enters the plate.
• e.g., LA Dodgers
• The Los Angeles Dodgers were named after the'Dodgers' because there were many trams in the Brooklyn, New York area, which was formerly associated with the city.
• Pinch hitter
• A substitute batter. 
• Batters can be substituted at any time while the ball is dead (not in active play)
• The manager may use any player who has not yet entered the game as a substitute.
• Pinch runner
• A baseball player substituted for the specific purpose of replacing a player on base. 
• The pinch runner may be faster or otherwise more skilled at base-running than the player for whom the pinch runner has been substituted.
• Starting pitcher
• the first pitcher in the game for each team
• Relief pitcher
• a pitcher who enters the game after the starting pitcher is removed
• c.f., long reliever
• a relief pitcher in baseball who enters the game if the starting pitcher leaves the game early
• c.f., middle reliever
• relief pitchers who commonly pitch in the fifth, sixth, or seventh inning
• c.f., setup pitcher (setup man)
• a relief pitcher who regularly pitches before the closer. They commonly pitch the eighth inning
• c.f., closing pitch (closer)
• a relief pitcher who specializes in getting the final outs in a close game when his team is leading. 
• The role is often assigned to a team's best reliever.

Football position

Football position

• Sweeper
• The sweeper (or libero (Italian: free)) is a more versatile type of centre-back that, as the name suggests, "sweeps up" the ball if the opponent manages to breach the defensive line. 
• Their position is rather more fluid than other defenders who mark their designated opponents
• Full-back
• The left-back and the right-back are generally referred to as the full-backs
• Wing-back
• The wing-back (or attacking full-back) are defenders with heavier emphasis on attack
• usually employed as part of a 3–5–2 formation, and can therefore be considered part of the midfield when a team is attacking
• one of the most physically demanding positions
• Wide-midfield
• With the advent of the modern game the traditional outside forwards known as "wingers" were pushed back to wide midfield, though still commonly referred to as wingers
• Wingers
• A winger (left winger and right winger) (historically called outside-left and outside-right, or outside forward) is an attacking player who is stationed in a wide position near the touchlines

5G

5G

• The fifth generation technology standard for broadband cellular networks, which cellular phone companies began deploying worldwide in 2019
• c.f., broadband
• Wide bandwidth data transmission which transports multiple signals and traffic types. 
• The medium can be coaxial cable, optical fiber, radio or twisted pair.
• c.f., cellular network (or mobile network)
• a communication network where the last link is wireless
• The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver
• Capacity
• 5G can support up to a million devices per square kilometer, while 4G supports only up to 100,000 devices per square kilometer
• Speed
• The main advantage of the new networks is that they will have greater bandwidth, giving higher download speeds, eventually up to 10 gigabits per second (Gbit/s)
• Use
• Due to the increased bandwidth, it is expected the networks will not exclusively serve cellphones like existing cellular networks, but also be used as general internet service providers for laptops and desktop computers, competing with existing ISPs such as cable internet, and also will make possible new applications in internet of things (IoT) and machine to machine areas.
• Three frequency bands
• The increased speed is achieved partly by using higher-frequency radio waves than previous cellular networks.
• However, higher-frequency radio waves have a shorter useful physical range, requiring smaller geographic cells. 
• For wide service, 5G networks operate on up to three frequency bands — low, medium, and high
• The first mobile phone
• Samsung Galaxy S10 5G, the first smartphone able to connect to 5G networks

Fatty liver

Fatty liver

• Fatty liver refers to when the amount of fat deposited in the liver is more than 5% of the weight of the liver. 
• About 5% fat is present in the normal liver. 
• Among fats, neutral fats, i.e., triglycerides accumulate in liver cells.
• Causes
• The four major causes of fatty liver are excessive alcohol consumption, obesity (abdominal obesity), diabetes, and hyperlipidemia.
• Treatment methods (if obesity is the cause)
• Weight loss
• Slowly lose 10% of your current weight within 3-6 months. Too sudden weight loss can worsen fatty liver.
• Diet
• Eat meals three time a day without skipping, but reduce the amount of one meal little by little. 
• Avoid midnight snack and overeating, and eat a balanced diet. 
• If you are overeating, do more exercise than usual to consume more energy.
• It is better to drink boiled foods than fried foods, and water or green tea types rather than sugary drinks. 
• Eat food slowly 

Townhouse

Townhouse

• A type of terraced housing where a row of identical or mirror-image houses share side walls
• A modern townhouse is often one with a small footprint on multiple floors. 
• In the United Kingdom, most townhouses are terraced.
• Only a small minority of them, generally the largest, were detached, but even aristocrats whose country houses had grounds of hundreds or thousands of acres often lived in terraced houses in town.
• Townhouses are expensive where detached single-family houses are uncommon, such as in New York City, Chicago, and Boston

Changes in income requirements for newlyweds

• The government will significantly ease the income requirements for the subscription of specially supplied housing for newlyweds and first-time consumers
• special supply : newlyweds
• special supply : first home purchase in life

Newlyweds (특별공급: 신혼부부)

Special supply 

• Special supply is a system that supports housing arrangements for social classes that need policy consideration, such as multi-child households, newlyweds, people of national merit, and caregivers of elderly parents.
• e.g., newlyweds (national or private)
• Pre-sale housing with an exclusive area of ​​85m² or less
• e.g., newlyweds (sales conversion rental housing)
• Pre-sale housing or sales conversion rental housing, with an exclusive area of ​​85m² or less 

First home purchase in life (특별공급: 생애최초 주택구입)

Special supply

• Special supply is a system that supports housing arrangements for social classes that need policy consideration, such as multi-child households, newlyweds, people of national merit, and caregivers of elderly parents.
• e.g., first home purchase in life
• target person
• houseless + married + tax payment + income level + assets level

Housing subscription (apartment application)

Type of house

• National housing
• Houses with a residential area of ​​85m² or less built by the state, local governments, LH and local corporations
• c.f., ​​85m² = 25.7125평
• Private housing
• Housing excluding national housing

Korea Land and Housing Corporation (LH, 한국토지주택공사)

LH

• Consolidation of Korea National Housing Corporation and Korean Land Corporation (October 2009)
• Korea National Housing Corporation (대한주택공사)
• Korea Land Corporation (한국토지공사)
• Part of the plan to advance public enterprises
• Eliminate redundant functions
• Apartment Brand
• e.g., Humansia

Decaffeination

Decaffeination

• The removal of caffeine from coffee beans, cocoa, tea leaves, and other caffeine-containing materials. 
• Decaffeinated drinks contain typically 1–2% of the original caffeine content, and sometimes as much as 20%.
• Process
• Various methods can be used for decaffeination of coffee. 
• These methods take place prior to roasting and may use organic solvents such as dichloromethane or ethyl acetate, supercritical CO2, or water to extract caffeine from the beans, while leaving flavour precursors in as close to their original state as possible
• e.g., The first commercially successful decaffeination process was invented by German merchant Ludwig Roselius and co-workers in 1903, after Ludwig observed that a freight of coffee beans accidentally soaked in sea water had lost most of their caffeine content without losing much of their flavour

Joule

Joule

• Joule is the international unit of energy or work. 
• The symbol is the Latin capital letter J.
• Formula
• 1J = 1 N*m
• 1 joule is the energy required for or work done when an object is moved one meter with a force of one Newton
• Orgin
• James Prescott Joule
• British physicist and brewer
• One of the discoverers of the law of conservation of energy.
• c.f., the law of conservation of energy
• Energy can only change its form or transfer to another, but cannot be created or lost.
• e.g., In roller coasters, potential energy due to gravity is converted into kinetic energy, or chemical energy of gunpowder is converted into kinetic energy of bullets.

Singapore

Singapore

• Official languages
• English, Malay, Chinese, and Tamil
• c.f., Tamil
• the official language of the Indian state of Tamil Nadu
• c.f., Tamil Nadu
• one of the 28 states of India
• Self-governance
• gained in 1959, and in 1963 became part of the new federation of Malaysia
• Ideological differences led to Singapore being expelled from the federation in 1965
• Lee Kuan Yew (~1990, for 31 years) and Yusof bin Ishak (~1970, died) as the first prime minister and president respectively
• Economy
• A major financial and shipping hub
• has been identified as a tax haven
• c.f., tax haven
• a country or place with very low effective rates of taxation for foreign investors
• has been one of the few countries with an AAA credit rating from the big three, and the only Asian country to achieve this rating
• c.f., the big three
• S&P Global Ratings (S&P), Moody's, and Fitch Group.
• Politics
• a parliamentary republic based on the Westminster system
• The president 
• head of state and exercises executive power on the advice of her ministers
• The prime minister
• head of government and is appointed by the president as the person most likely to command the confidence of a majority of Parliament
• Cabinet is chosen by the prime minister and formally appointed by the president

Price-to-Earnings Ratio (P/E Ratio)

P/E ratio

• relates a company's share price to its earnings per share
• known as the price multiple
• used to compare a company against its own historical record 
• Companies that have no earnings or that are losing money do not have a P/E ratio
• since there is nothing to put in the denominator
• Analysts and investors review a company's P/E ratio when they determine if the share price accurately represents the projected earnings per share. 
• Formula
• P/E ratio = market value per share / earnings per share
• 
  

Semi-conductor

Semi-conductor

• A semiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic copper, and an insulator, such as glass. 
• Its resistivity falls as its temperature rises; metals behave the opposite. 
• Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. 
• When two differently-doped regions exist in the same crystal, a semiconductor junction is created.
• c.f., p-n junction
• a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. 
• The "p" (positive) side contains an excess of holes, while the "n" (negative) side contains an excess of electrons in the outer shells of the electrically neutral atoms there. 
• This allows electrical current to pass through the junction only in one direction.
• c.f., holes
• the lack of an electron
• The p-n junction is created by doping
• c.f., doping
• the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties
• c.f., charge carrier
• a particle or quasi-particle that is free to move, carrying an electric charge
• The behavior of charge carriers, which include electrons, ions and electron holes, at these junctions is the basis of diodes, transistors and all modern electronics.

Difference of semiconductors and conductors

• Conductors
• hard to control although it conducts well
• Semiconductors
• easy to change its properties by applying an artificial manipulation such as adding impurities
• Different manipulations can lead to different things a semiconductor can do

Transistor

Transistor

• A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. 
• c.f., switch
• can be either in an "on" or "off" state
• It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. 
• A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. 
• Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal.

Battery vs. capacitor

Battery vs. capacitor

• While a battery uses chemical reactions to store electrical energy and releases power very slowly through an electronic circuit, capacitors are capable of releasing energy very rapidly.
• Energy is stored inside the battery in the form of chemical energy which gets converted into electrical energy, releasing electricity through a chemical reaction which eventually generates an electric current.
• This is why batteries store a lot of charge but they charge/discharge very slowly
• A capacitor contains at least two electrical conductors separated by an insulator (dielectric). 
• When an electric field develops across the insulator, it stops the flow and an electric charge is starting to build up on the plates.

Resistance vs. conductance

Resistance

• a measure of its opposition to the flow of electric current. 
• Electrical resistance shares some conceptual parallels with the notion of mechanical friction.
• measured in ohm
• depends in large part on the material it is made of. 
• Objects made of electrical insulators like rubber tend to have very high resistance and low conductivity, while objects made of electrical conductors like metals tend to have very low resistance and high conductivity.
• formula
• R = V / I
• Resistivity
• quantifies how strongly it resists electric current
• represented by the Greek letter ρ (rho).
• SI unit of electrical resistivity is the ohm-meter (Ω⋅m)

Conductance 

• the ease with which an electric current passes.
• measured in siemens
• formula
• G =  I / V = 1 / R
• Conductivity
• quantifies how strongly it conducts electric current
• The SI unit of electrical conductivity is siemens per metre (S/m).

Battery performance & temperature

• When temperatures drop the internal resistance of the battery is increased. 
• This means that it requires more effort by the battery to charge, in turn lowering the capacity.

Battery

Electric battery

• A device that stores chemical energy and converts it to electrical energy.
• a device consisting of one or more electrochemical cells with external connections for powering electrical devices
• c.f., electrochemical cells
• a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions.
• Each electrochemical cell consists of two electrodes separated by an electrolyte.
• The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. 
• c.f., chemical reactions
• a process that leads to the chemical transformation of one set of chemical substances to another.
• e.g., changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms
• The flow of electrons provides an electric current that can be used to do work.
• To balance the flow of electrons, charged ions also flow through an electrolyte solution that is in contact with both electrodes.
• c.f., electrolyte solution
• a substance that is split into ions in an aqueous solution state and flows current. 
• e.g., NaCl
• it does not pass current in a solid state, but can become an electrolyte because it passes current in an aqueous solution state.
• An electrolyte can be a liquid, gel or a solid substance, but it must be able to allow the movement of charged ions. 
• c.f., ions
• refers to an atom or molecule that loses or gains an electron
• When the electrolyte is dissolved in water, it is divided into positive and negative ions. 
• This phenomenon is called 'ionization'

The flows of electrons (electrochemical cells)

• Electricity is a type of energy produced by the flow of electrons. 
• In an electrochemical cell, electrons are produced by a chemical reaction that happens at one electrode and then they flow over to the other electrode where they are used up.
• The electrons flow from one electrode called the anode (or negative electrode) to another electrode called the cathode (the positive electrode). 
• c.f., electrodes
• generally different types of metals or other chemical compounds.
• In Volta’s pile, the anode was the zinc, from which electrons flowed through the wire (when connected) to the silver, which was the battery’s cathode. 
• He stacked lots of these cells together to make the total pile and crank up the voltage. 
• At the anode, the electrode reacts with the electrolyte in a reaction that produces electrons. 
• These electrons accumulate at the anode. 
• As the chemical reaction at the anode produces electrons, to maintain a neutral charge balance on the electrode, a matching amount of positively charged ions are also produced. These don’t go down the external wire (that’s for electrons only!) but are released into the electrolyte.
• Meanwhile, at the cathode, another chemical reaction occurs simultaneously that enables that electrode to accept electrons.
• The cathode must also balance the negative charge of the electrons it receives, so the reaction that occurs here must pull in positively charged ions from the electrolyte

Increasing a battery's voltage

• To increase a battery’s voltage, we’ve got two options. 
• We could choose different materials for our electrodes, ones that will give the cell a greater electrochemical potential. 
• Or, we can stack several cells together. 
• c.f., When the cells are combined in a particular way (in series), it has an additive effect on the battery’s voltage.
• When cells are combined in another way (in parallel) it increases the battery’s possible current, which can be thought of as the total number of electrons flowing through the cells, but not its voltage.

Battery recharging

• The flow of ions and electrons, as it takes place in some types of batteries that have appropriate electrode materials, can also go backwards, taking our battery back to its starting point and giving it a whole new lease on life
• When we connect an almost flat battery to an external electricity source, and send energy back in to the battery, it reverses the chemical reaction that occurred during discharge. 
• This sends the positive ions released from the anode into the electrolyte back to the anode, and the electrons that the cathode took in also back to the anode
• The memory effect
• When you recharge some types of rechargeable batteries without sufficiently discharging them first, they ‘remember’ where they were up to in earlier discharge cycles and don’t recharge properly.
• The memory effect is strong for some types of cells, such as nickel-based batteries. 
• Other types, like lithium-ion, don’t suffer from this problem.
• Another aspect
• The chemistry that makes them rechargeable also means they have a higher tendency towards self-discharge
• The lithium-ion batteries in our mobile phones
• have a pretty good self-discharge rate of around 2–3 per cent per month
• Lead-acid car batteries
• are also pretty reasonable—they tend to lose 4–6 per cent per month.
• Nickel-based batteries 
• lose around 10–15 per cent of their charge per month, which is not very good
• A non-rechargeable alkaline battery only loses around 2–3 per cent of its charge per year.  

Combinations of different materials of metals

• A range of materials (it used to be just metals) can be used as the electrodes in a battery 
• Different materials have different electrochemical properties, and so they produce different results when you put them together in a battery cell.
• Often two or more battery cells need to be stacked to obtain the required voltage
• The lithium iron phosphate batteries (a type of lithium-ion battery) used in electric cars stack together to make high voltage systems (100 or even more volts)

Capacitor

Capacitor

• a device that stores electrical energy in an electric field
• c.f., electric field
• the space where the electric force exerts between the positive (+) charge and the negative (-) charge
• c.f., electric charge
• Electric charge is the amount of static electricity carried by an object and is the substance that is the source of all electrical phenomena. 
• There are positive and negative charges, and it is the current that the charges move.
• c.f., static electricity
• Static electricity is electricity in which an electric charge remains stationary and does not flow. 
• Collects and releases electric charges to provide stable electricity.
• Condenser
• The capacitor was originally known as a condenser
• Inside the capacitor, the two conductor plates are separated, and an insulator is usually inserted between them.
• Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium
• The nonconducting dielectric acts to increase the capacitor's charge capacity.
• c.f., dielectric
• an electrical insulator that can be polarized by an applied electric field. 
• When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor but only slightly shift from their average equilibrium positions causing dielectric polarization. 
• Because of dielectric polarization, positive charges are displaced in the direction of the field and negative charges shift in the direction opposite to the field
• Charges are stored at the boundary between the surface of each plate and the insulator, and the amount of charges collected on both surfaces is the same, but the sign is opposite. 
• That is, when a voltage is applied between the two conductor plates, a negative charge is induced to the negative electrode and a positive charge is induced to the positive electrode, resulting in electrical attraction. 
• Because of the electrical attraction, energy is stored