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Data resource profile: the Korean Working Conditions Survey (KWCS)
Cho Yoonho 대한직업환경의학회 2023 대한직업환경의학회지 Vol.35 No.1
The Korean Working Conditions Survey (KWCS) is a state-approved statistical survey that has been conducted by the Occupational Safety and Health Research Institute (OSHRI) every 3 years since 2006 to monitor changes in the working conditions of Koreans. This crosssectional national survey involves a sample of 50,000 employed people aged 15 or older. KWCS measures various working conditions through > 130 survey questions, including questions regarding working hours, labor intensity, work–life balance, degree of exposure to risk factors, and subjective health status. Professional survey interviewers visit households and conduct face to face interviews. KWCS provides data and statistics for occupational safety and health polices and research in Korea. Furthermore, OSHRI holds academic conferences every year, awards high-quality academic papers, and supports researchers using data. Microdata is publicly available through the OSHRI website (https://oshri.kosha.or.kr).
Yoonho Cho(조윤호),Jounghae Bang(방정혜) 한국지능정보시스템학회 2011 지능정보연구 Vol.17 No.3
Collaborative Filtering (CF) suffers from two major problems:sparsity and cold-start recommendation. This paper focuses on the cold-start problem for new customers with no purchase records and the sparsity problem for the customers with very few purchase records. For the purpose, we propose a method for the new customer recommendation by using a combined measure based on three well-used centrality measures to identify the customers who are most likely to become neighbors of the new customer. To alleviate the sparsity problem, we also propose a hybrid approach that applies our method to customers with very few purchase records and CF to the other customers with sufficient purchases. To evaluate the effectiveness of our method, we have conducted several experiments using a data set from a department store in Korea. The experiment results show that the combination of two measures makes better recommendations than not only a single measure but also the best-seller-based method and that the performance is improved when applying the hybrid approach.
Cho, Yoonho,Parmar, Narendra S.,Nahm, Sahn,Choi, Ji-Won Elsevier 2017 Ceramics international Vol.43 No.9
<P><B>Abstract</B></P> <P>In the quest of promising Indium free amorphous transparent conducting oxide (TCO), Zn-doped SnO<SUB>2</SUB>/Ag/Zn-doped SnO<SUB>2</SUB> (OMO) multilayer films were prepared on flexible polyethylene terephthalate (PET) substrates by RF sputtering at room temperature (RT). Growth parameters were optimized by varying sputtering power and working pressure, to have high electrical conductivity and optical transmittance. Optimization of the thickness of each layer was done by Essential Macleod Program (EMP) simulation to get the higher transmission through OMO multilayer. The sheet resistance and transmittance of 3at% Zn-doped SnO<SUB>2</SUB> thin film (30nm) were 2.23 kΩ/□, (ρ ~ 8.92×10<SUP>−3</SUP> Ω∙cm) and 81.3% (at λ ~ 550nm), respectively. By using optimized thicknesses of Zn-doped SnO<SUB>2</SUB> (30nm) and Ag (12nm) and optimized growth condition Zn-doped SnO<SUB>2</SUB>/Ag/Zn-doped SnO<SUB>2</SUB> multilayer thin films were deposited. The low sheet resistance of 7.2 Ω/□ and high optical transmittance of 85.1% in the 550nm wavelength region was achieved with 72nm multilayer film.</P>
[가솔린엔진부문] EGR 장착 스파크 점화 LPG 엔진의 성능 및 배기특성
조윤호(Yoonho Cho),구준모(Junemo Koo),김정헌(Jeongheon Kim),김승규(Seunggyu Kim),배충식(Choongsik Bae),오승묵(Seungmook Oh),강건용(Kemyong Kang) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
EGR (Exhaust Gas Recirculation) system has been used 10 reduce NO, emissions, improve fuel economy, and decrease thermal loading of engine because it offers the benefits of charge dilution as is the case with a lean bum technique. It is currently used in conventional engines, especially light-duty gasoline and diesel engines for a variety of advantages, and in recent years, it has become as a means of reducing engine-out emissions for heavy-duty vehicles as a consequence of the development of its control schemes as well.<br/> However, the occurrence of excessive cyclic variation with high EGR rates, especially at high load conditions, brings about the undesirable combustion instability within the engine cylinder, which results in the deterioration of both engine performance and emissions. Therefore, in order to avoid the reduction of thermal efficiency and to improve fuel economy, the optimum EGR rate depending on operating conditions of engine, should be derived effectively.<br/> An experimental study was conducted to investigate the effects of EGR on performance and emission characteristics of a spark-ignition LPG fuelled engine, and the feasibility of an enhanced methodology, such as a cooled EGR system.<br/>
가솔린엔진 대상 성능시험시의 노킹보정률을 사용한 엔진 수정토크의 편차개선
조윤호(Yoonho Cho),김용옥(Yongok Kim),이춘우(Chunwoo Lee),김우태(Wootai Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recent trends of development in small size gasoline engines are both to have higher compression ratio for the purpose of improved fuel consumption and to advance spark timing up to DBL in a low to mid engine speed region for a good acceleration performance of vehicles. However, there occurs the deviation of corrected engine torque results during engine performance test on dynamometer because test conditions influence the onset of knock. Therefore, this research shows the test deviation of corrected engine torque decreases when knock correction rate is used.
조윤호(Yoonho Cho),방정혜(Jounghae Bang) 한국지능정보시스템학회 2009 지능정보연구 Vol.15 No.4
Collaborative Filtering is one of the most used recommender systems. However, basically it cannot be used to recommend new products to customers because it finds products only based on the purchasing history of each customer. In order to cope with this shortcoming, many researchers have proposed the hybrid recommender system, which is a combination of collaborative filtering and content?based filtering. Content?based filtering recommends the products whose attributes are similar to those of the products that the target customers prefer. However, the hybrid method is used only for the limited categories of products such as music and movie, which are the products whose attributes are easily extracted. Therefore it is essential to find a more effective approach to recommend to customers new products in any category. In this study, we propose a new recommendation method which applies centrality concept widely used to analyze the relational and structural characteristics in social network analysis. The new products are recommended to the customers who are highly likely to buy the products, based on the analysis of the relationships among products by using centrality. The recommendation process consists of following four steps; purchase similarity analysis, product network construction, centrality analysis, and new product recommendation. In order to evaluate the performance of this proposed method, sales data from H department store, one of the well?known department stores in Korea, is used.
사회연결망분석과 인공신경망을 이용한 추천시스템 성능 예측
조윤호(Yoonho Cho),김인환(Inhwan Kim) 한국지능정보시스템학회 2010 지능정보연구 Vol.16 No.4
협업필터링 추천은 다양한 분야에서 활용되고 있지만 트랜잭션 데이터의 성격에 따라 추천 성능에 현저한 차이를 보이고 있다. 기존 연구에서는 이러한 추천 성능의 차이가 나타나는 이유에 대한 설명을 구체적으로 제시하지 못하고 있고 이에 따라 추천 성능의 예측 또한 연구된 바가 없다. 본 연구는 사회네트워크분석과 인공신경망 모형을 이용하여 협업필터링 추천시스템의 성능을 예측하고자 한다. 본 연구의 목적을 달성하기 위해 국내 백화점의 트랜잭션 데이터를 기반으로 형성되는 고객간 사회 네트워크의 구조적 지표를 측정한 후 이를 기반으로 인공신경망 모형을 구축하고 검증한다. 본 연구는 협업필터링 추천 성능을 예측할 수 있는 새로운 모형을 제시하였다는 점에서 그 의의가 있으며 이를 통해 기업들의 협업필터링 추천시스템 도입에 대한 의사결정에 도움을 줄 수 있을 것으로 기대된다.