Optimal Contracts under Moral Hazard and Costly Lying

( Keeyoung Rhee ) 한국경제학회 2021 The Korean Economic Review Vol.37 No.1

We present a model in which the agent reports a privately observed signal about the stochastic outcome of her action, while bearing a cost of misreporting her private information. If the agent receives a low payment contingent on her performance, it is very costly for the agent to misreport her information to the principal so that the principal makes a decision favorable to the agent. However, if the contingent compensation is too high, the principal will terminate the project unless the agent truthfully reports that the project is likely to give a high return. The optimal outcome is achieved by a contract with the fee structure loosely tied with the outcome, but the cost of lying is necessarily high.

Calibration of Inertial Measurement Units Using Pendulum Motion

Keeyoung Choi,Se-ah Jang,Yongho Kim 한국항공우주학회 2010 International Journal of Aeronautical and Space Sc Vol.11 No.3

The utilization of micro-electro-mechanical system (MEMS) gyros and accelerometers in low-level inertial measurement unit (IMU) influences cost effectiveness in a positive way under the condition that device error characteristics are fully calibrated. The conventional calibration process utilizes a rate table; however, this paper proposes a new method for achieving reference calibration data from the natural motion of pendulum to which the IMU undergoing calibration is attached. This concept was validated with experimental data. The pendulum angle measurements correlate extremely well with the solutions acquired from the pendulum equation of motion. The calibration data were computed using the regression method. The whole process was validated by comparing the measurement from the 6 sensor components with the measurements reconstructed using the identified calibration data.

Improvement of Optical Disk Controller Using a MEMS Accelerometer

Keeyoung Choi,Sunghee Kim,Jintai Chung 제어로봇시스템학회 2002 제어로봇시스템학회 국제학술대회 논문집 Vol.2002 No.10

Estimation of Reused Household Waste in Seoul

( Keeyoung Yoo ),( Koun Kim ),( Wonsam Kang ),( Hyejin Lee ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

People in Seoul have been actively engaged with the various activities of household waste reuse: however, how much household wastes have been reused is not well-known. This study aims to estimate the amount of reuse in Seoul. Based on a survey of 1,500 Seoul citizens, 69.5% were found to be engaged in repair, 50% in donation, 55% in purchase and 45.3% in sales. People are willing to participate in reuse activities more in the future, which will result 16.5%p ~ 25.4%p increase of citizen participation. Based on a material flow analysis of reuse organizations, resale rate versus collected goods in charity shops covered 20.6%, while the rate in the recycling centers managed by the district authorities was 61.8% and the rate in the clothing box operators, monitored by the district authorities, was 65.6%. The average annual amount of collected reused goods per reuse facility in 2019 differs according to its type: charity shops reported 135.3 tons, recycling centers collected 410 tons, and 17 tons were collected from 10,000 households by a waste clothing box operator. Through combining a citizen survey and a material flow analysis of reuse facilities, the amount of reused household waste in Seoul is estimated as 33,742 tons collected and 15,852 tons sold annually. Therefore 47% of the collected was reused and the rest were mostly moved to recycling companies. Reuse per capita per year was calculated as 1.6kg. Because ‘reuse’ or ‘preparation for reuse’ is not fully covered in official waste statistics, the estimated result of this study adds up household waste generation by 0.4%, which contributed to the increase of recycling rate by 0.1%p. The quantification of reuse is essential to achieve Seoul’s policy goals to become a circular city. So three basic conditions are recommended : 1) to single out the amount of ‘preparation for reuse’ excluding customer-to-customer (C2C) transactions; 2) to figure out the exact amount of reused goods sold and; 3) to establish a data collection and monitoring system covering the amount of collected and traded goods in reuse facilities managed or monitored by the district authorities.

Optical Characteristics Comparison Between a Three-striped LED and a Conventional GaN-based LED

Keeyoung Kwon,Janggeun Ki 대한전자공학회 2019 IEIE Transactions on Smart Processing & Computing Vol.8 No.4

In this paper, we propose a new light-emitting diode structure with three stripes. We analyze the effect of the tapered structure of the proposed three-striped LED on photon extraction efficiency and on the mean photon path length, compared with a conventional LED structure. The effect of the absorption loss from p-metal and n-metal electrodes on photon extraction efficiency and the mean photon path length are also studied by comparing the three-striped LED with the conventional LED structure. In the three-striped LED, photon extraction efficiency is 40.7%, which is greater than the conventional gallium-nitride (GaN)-based LED, when Fresnel reflection at the semiconductor air interface is the only mechanism to prevent emitting of light.

Case Study on the Environmental Impact of C&D Waste Facility

( Keeyoung Yoo ),( Siwoo Lee ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

When environmental regulations were not strict, waste treatment facilities quipped with poor prevention of environmental pollution did often site in the outskirts of urban areas. However, due to concentration of population, industry, and culture, those facilities are surrounded by residential and commercial buildings, and have been emerging as a cause of social conflict. There is such a C&D facility in Seoul which has been asked to move out from residents. The local district issued permission is demanded by the residents to take measures about that facility as well. This study surveyed what kind of environmental damages to surrounding area are caused by the facility using resident questionnaire survey, environmental pollutants measurement, and atmospheric dispersion modeling. Residents questionnaire survey revealed that residents living within 1 km from the facility could have been negatively affected by picking answer to be damaged much more than residents living over 1 km. Residents also mentioned dust as main pollutants, and field survey illustrated that dusts were coming from C&D crusher, yard stock of crushed aggregate, sediments on the road surface dropped from C&D transportation vehicles, and so on. According to environmental pollutants measurement, the concentration of fine dust exceeded limitedly the environmental standard in the facility site, in the area of neighboring the facility site and in the residential area closest to the facility site. Atmospheric dispersion modeling resulted that the facility is causing 20~39% of fine dusts, 56~92% of nitrogen dioxide and 72~88% of noise to the closest residential area. As a short-term measure to reduce damage to surrounding areas, it is desirable to confine crushers in the building and purify pollutants, and to wash away dusts on the surface of site and surrounding roads. If not, closure of the facility or move out to other area should be considered.

The Comparison and analysis of the color development on the heavy metal content of the eyeliner products on sale

KeeYoung Lee 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10

Colors cosmetics are made up of large amounts of pigments. Among them, the color of the eyeliner includes the largest am ount of the total content among cosmetics from 20% to 25%. This may be higher than the other color cosmetics on the heavy metal content due to the addition of pigment I have been studied w whether the color formation, which is an important part of cosmetics as the pigments of the color cosmetics, is related to the contents of the heavy metals. In this study, we examined that the content of the heavy metal affected the color formation of the black eyeliner by measuring the color formation and the content of the heavy metal of eyeliner, which contains the most pigment. The eyeliner was measured by collecting 10 black gels, which are currently on sale in the domestic market. The pigment of eyeliner contains mainly Red, Yellow,Black Iron Oxide, Carbon Black and Tar Color. As the result, Pb, As in 10 black eyeliners, regulated by the Food and Drug Administration (KFDA), were found within the standard of permission. But the aluminium and manganese, which don’t have the standard of permission, were found to be high. In particular, the largest metal component was significantly higher in aluminum, with a maximum of 19,321 ppm than other heavy metals. Color formation of the eyeliner product was shown at the highest level of L * 26.54, lowest L, and 22.3. Since it is a black product, it is difficult to tell because the color is less than 0.3 with the naked eyes, but in the most products, the color shows red level and blue level, and it is distributed in PBS, P, RP, and R. Among them, the colors have the most amount in PB, so the black color reveals blue. The black level showed no significant difference between the water-proof products with the high contents of the heavy metal and other generic products. Therefore, it was discovered that the metallic content of the eyeliner didn’t affect the color formation of the color by measuring the metallic content and color formation of the eyeliner. Later, I think that it is necessary to research on the relation of usability, and persistence due to heavy metal content of color cosmetic products.

시내버스 차량의 제상성능 개발에 관한 연구

양기영(Keeyoung Yang),문지현(Jihyun Moon),조성필(Sungpil Jo),정병만(Byoungman Jung) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2007 No.11

CFD를 통한 중소형트럭 흡기계 성능개선에 관한 연구

양기영(Keeyoung Yang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1

The performance of the air induction system is important to the long-term performance and reliability of the engine and its component. In this study. the air induction system of mid-sized truck was picked out some problems for particle separation and discharge performance by using CFD. We could get four design parameters into analysis for base model. An L9 orthogonal table was applied to optimization for design parameters. The particle tracking method was an useful method for inspection of dust behavior. We carried out numerical analysis for performance about each case of orthogonal table. Finally. We did bench test and vehicle test for verification tor the result of CFD.

다중 경로점 제한 조건하의 헬리콥터의 최적 경로 생성

최기영(Keeyoung Choi) 한국항공우주학회 2003 韓國航空宇宙學會誌 Vol.31 No.8