The purpose of this study is to analyze the adequacy of production capacity of the assembly process system of mobile bath vehicle’s top box panel and process design through a simulation analysis. Towards this end, the layout of the facility designed with pre-verification job using a simulation modeling and an experiment, and facility, logistics process, and personnel input method were made into a simulation model, and the design system’s adequacy was evaluated through an experiment. To produce 120 mobile bath vehicles annually, it was analyzed that 14 general workers and seven skilled workers were adequate through the experiment. It was also identified that three painting process lines carried out through outsourcing were adequate. Production lead time was 201.7 hours on average and it was 230 hours maximum. To meet customer delivery service level of 95% within the deadline when establishing a customer order and vehicle delivery plan, it was analyzed that more than 215 hours of lead time is needed minimum. If the process cycle time is reduced to 85% upon system stabilization and skillfulness improvement, it was analyzed that annual output of 147 vehicles can be achieved without additional production line expansion.

In addition to physical risks such as electrical, chemical, and mechanic ones in the workplace, psychosocial risks are also raising as an important issue in recent years in connection with human rights and work-life balance policies. The purpose of this study is to confirm the degree of effect of the psychosocial risk management plan at the workplace on workers through logistic regression analysis. Input data for logistic regression analysis is the results of a survey of 4,558 people conducted by the Institute for Occupational Safety and Health were used. There are 9 independent variables, including the change a workplace and confidential counseling, and the dependent variable is whether the worker feels the effect on the psychosocial risk management plan. As a result of this study, changes in work organization, dispute resolution procedures, provision of education program, notification of the impact of psychosocial risks on safety and health, and the persons in charge of solving psychosocial problems are shown effective in reducing worker’s psychosocial risks. This study drives which of the management plans implemented to reduce the psychosocial risk of workers in the workplace are effective, so it can contribute to the development of psychosocial risk management plans in the future.

Companies widely use survey to identify customer requirements, but the survey has some problems. First of all, the response is passive due to pre-designed questionnaire by companies which are the surveyor. Second, the surveyor needs to have good preliminary knowledge to improve the quality of the survey. On the other hand, text mining is an excellent way to compensate for the limitations of surveys. Recently, the importance of online review is steadily grown, and the enormous amount of text data has increased as Internet usage higher. Also, a technique to extract high-quality information from text data called Text Mining is improving. However, previous studies tend to focus on improving the accuracy of individual analytics techniques. This study proposes the methodology by combining several text mining techniques and has mainly three contributions. Firstly, able to extract information from text data without a preliminary design of the surveyor. Secondly, no need for prior knowledge to extract information. Lastly, this method provides quantitative sentiment score that can be used in decision-making.

절화장미 삽목묘 대량생산 효율을 높이기 위해 국내 육성 절화장미 ‘엔틱컬’(Rosa hybrida ‘Antique Curl’)을 대상으로 생장 활력이 높은 단경삽목묘 주요 절위를 분석하였다. 화경으로부터 순서대로 5매엽 이상을 가진 마디 6개를 삽목(6 절위, Level 1~6)하여 온실과 생장환경조절실에서 각각 30일간 관리 하였다. 그 결과, 삽목 절위가 기부 쪽으로 내려갈수록 발근율과 액아 생장이 억제되었고, 삽수 잎의 황화 및 낙엽 현상이 조기에 나타났다. 잎의 탄수화물 함량은 발근과 신초발아율에 영향을 주지 않았다. 온실환경에서 1~3 절위, 생장환경조절실 에서 1~2 절위의 생장이 가장 우수하였고, 모두 4절위까지는 정상적인 생장을 보였다. 결과적으로 상업용 장미 시설 생산에서 대량삽목번식을 할 때 화경으로부터 5매엽을 가진 네번 째 마디(level 4)까지 가능할 것으로 확인되었다.

It is highly challenging to measure the efficiency of electric vehicle charging stations (EVCSs) because factors affecting operational characteristics of EVCSs are time-varying in practice. For the efficiency measurement, environmental factors around the EVCSs can be considered because such factors affect charging behaviors of electric vehicle drivers, resulting in variations of accessibility and attractiveness for the EVCSs. Considering dynamics of the factors, this paper examines the technical efficiency of 622 electric vehicle charging stations in Seoul using data envelopment analysis (DEA). The DEA is formulated as a multi-period output-oriented constant return to scale model. Five inputs including floating population, number of nearby EVCSs, average distance of nearby EVCSs, traffic volume and traffic congestion are considered and the charging frequency of EVCSs is used as the output. The result of efficiency measurement shows that not many EVCSs has most of charging demand at certain periods of time, while the others are facing with anemic charging demand. Tobit regression analyses show that the traffic congestion negatively affects the efficiency of EVCSs, while the traffic volume and the number of nearby EVCSs are positive factors improving the efficiency around EVCSs. We draw some notable characteristics of efficient EVCSs by comparing means of the inputs related to the groups classified by K-means clustering algorithm. This analysis presents that efficient EVCSs can be generally characterized with the high number of nearby EVCSs and low level of the traffic congestion.

해상풍력발전기 설치선의 동적응답을 분석하기 위하여, 불규칙 파 정보를 고려한 시간영역 기반 비선형동적해석이 필요하다. 고전적인 단자유도 시스템은 가장 기본적으로 동적효과를 계산하는 방법이지만, 실제의 무게 중심 불일치, 비정규적인 파도 하중 그리고 항력의 비선형을 고려하지 못하는 제약조건들을 갖고 있다. 그리하여 불규칙 파를 고려한 다중 자유도 모델이 유사한 문제에 해답을 찾는데 폭넓게 사용되고 있다. 불규칙 시간영역 해석은 정확한 계산 결과를 제공하지만, 수렴 데이터의 수렴도가 민감하여 복잡하다. 이러한 제약점들을 극복하기 위하여 본 논문은 시간영역 해석 결과를 통하여 수정된 동적증폭계수를 개발하였으며, 기존보다 복잡성이 개선되면서 계산 시간을 획기적으로 단축하였다. 다양한 변수를 기준으로 한 시간영역 해석을 통하여 새롭게 개발된 동적증 폭계수는 단자유도 방법보다 더 높은 정도를 갖고 있으며, 예측이 가능하다.