• KIEAE Journal
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• 제10권3호
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• pp.43-50
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• 2010

Natural lighting is directly connected with our mental and physical health. For working or learning effect, the proper natural lighting is required for improving our living conditions. School facilities, especially, are the place where includes students' ordinary activities with learning behaviors during the school years from elementary to high school. This study was carried out for the purpose introducing a basic database in that planning a school by researching on the actual in the natural lighting system of some schools' classroom, estimating, and analyzing through a simulation, which resulted in a method of improving the natural lighting system. As a result of measuring and analyzing Daylight Factor(DF) during the time from 9 am to 3 pm when students are activating in their classroom, generally DF range of the sides near to window and aisle seats zone are not distributed well. Besides, two out of four school which are researched would not reach the standards of the law for school sanitary while rest of the schools meet the standards; Average DF 5% and Minimum DF 2%. And the result of a simulation by RADIANCE program shows the most appropriate DF range when it is applied in variable numbers about an oriehows the- South-east 15, south-east 30, south-east 45, south-west 15, south-west 30, and south-west 45 degrees. When it is applied in the variable numbers about glass transmittance - 60%, 70%, and 80% in condition facing south of a classroom, the result shows that the DF range of 80% transmittance is relatively higher than other glasses in the classroom. Thus, when a school is built, plans for an orientation is necessary for improve of elementary schools' environment with the glass installation which is made for high transmittance and is regarded with the students' activities time.

• 한국도로학회논문집
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• 제9권2호
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• pp.77-87
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• 2007

고속도로의 교통사고는 다양한 원인들에 의해 발생되고, 그중 운전자의 부주의는 가장 중요한 교통사고 원인으로 알려져 있다. 주의 및 규제표지와 노면요철포장 등의 도로안전시설은 이러한 운전자 부주의를 막기 위해 설치 운영되고 있다. 본 연구에서는 서해안고속도로 일부구간에 설치된 길어깨-노면요철포장의 교통사고감소 효과를 분석하기 위해 C-G 방법 (Hauer에 의해 개발된 비교그룹을 이용하는 사전 사후 분석방법)을 수행하였다. 분석결과 길어깨에 도로요철포장을 설치한 도로는 설치하지 않은 도로에 비해 차도이탈사고가 연간 2.43건 정도 감소한 것으로 나타났으며 감소율은 0.38(표준편차 0.21)인 것으로 나타났다. 차도이탈사고는 교통사고 중 길어깨-노면요철포장 설치에 가장 민감하게 영향을 받는 사고형태이다. 본 연구를 통해 서해안고속도로에 설치된 길어깨-노면요철포장은 교통사고 감소에 기여한 것으로 분석되었으며, 특히 차도이탈사고가 현저하게 감소된 것으로 분석되었다.

• Journal of Acupuncture Research
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• 제35권3호
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• pp.108-114
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• 2018

Background: The purpose of this survey study was to understand how utilization of X-rays as an adjunct to Chuna manual therapy (CT) supports treatment, as assessed by Korean medicine doctors (KMDs). Methods: A survey was emailed to all 18,289 members of the Association of Korean Oriental Medicine (AKOM)to determine the implications of X-ray use in CT. Surveys were collected from September 22, 2017 to October 15, 2017. Results: Of the 18,289 KMDs 562 completed the survey. The implications of a radiological diagnosis (X-ray) with CT was assessed using 5 items in a questionnaire: time to diagnosis, accuracy of treatment, patient comprehension and satisfaction, CT effect, and safety of CT. Survey participants identified improvement in patient comprehension and satisfaction as the most important factor for X-ray use with CT, followed by increased safety of CT. From the determinant factors for selection of CT intensity and specific techniques, severity of clinical symptoms was shown to be the most influential factor. Degenerative changes of the spine and degree of spinal malposition were also reported to be highly influential. Conclusion: The KMDs' that participated in this study indicated that utilization of X-rays in conjunction with CT administration improved patient comprehension and satisfaction, and CT safety. Installation of radiological equipment in Korean medicine clinics where CT is provided may increase safety and patients' satisfaction.

• Journal of Forest and Environmental Science
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• 제34권2호
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• pp.176-179
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• 2018

To restore the connectivity of fragmented habitats, 415 wildlife crossings have been built between 1998 and 2014 in South Korea. However, their effect on wildlife conservation is still in doubt. As a first step to examine the effectiveness, our study aims to assess compliance with the guideline for wildlife crossing construction and management, developed by the Ministry of Environment Korea that provides fundamental information to understand the status and the problem of wildlife crossings in Korea and thus to provide practical guidance for the improvement. According to our survey, the Korea National Park Service complied with the guideline best (62.5%) while local government followed the guideline least (46.1%). In addition, the compliance rate was the highest for wildlife crossings in national roads (53.6%) followed by highways (53.2%) and local and municipal roads (52.2%). For the overpass wildlife crossings, the compliance rates for installation of an escaping facility in the drainage and prevention of pedestrian and vehicle access were particularly low. In case of underpass wildlife crossings, small ditches for amphibians and reptiles were not sufficient, and the linkage between wildlife fences and underpass were weak. In order to ensure the effectiveness of wildlife crossings, the effort to increase the compliance rate with the guideline is critical, and mandating the guideline could be a practical way to enforce the compliance.

• 한국지반공학회지:지반
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• 제9권3호
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• pp.23-34
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• 1993

지반조건이 개단강관말뚝의 거동에 미치는 영향을 규명하기 위하여 응력상태와 상대밀도의 조절이 가능한 토조내에 포설된 모래지반에서 모형말뚝실험이 수행되었다. 모형말뚝은 개단강관 말뚝의 각 부분에 작용하는 지지력을 분리측정하기 위하여 직경이 다른 두개의 파이프로 만들어졌다. 실험결과에 의하면 모래지반에 타입된 개단말뚝의 폐색정도와 관입저항력은 지반의 수직응력보다는 수평응력과 상대밀도에 의하여 좌우되었으며, 관내토지지력과 외주면마찰력, 그리고 전체 지지력도 수직응력보다는 수평응력과 상대밀도에 의하여 주로 영향받는 것으로 나타났다. 또 한 말뚝 외벽에 작용하는 수평응력은 원지반의 응력상태와는 관계없이 조밀한 지반의 경우에는 원지반의 수평응력보다 크게, 보통상태의 지반에서는 원지반과 비슷하게, 그리고 매우 느슨한 지반에서는 원지반보다 작게 측정되었다. 원지반의 수평응력에 대한 말뚝 설치후의 말뚝 외벽에 작용하는 수평응력의 비는 주어진 모래지반의 경우 원지반의 수평응력과 관계없이 상대밀도에 따라 일정한 값으로 나타났다.

• 한국전자통신학회논문지
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• 제6권6호
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• pp.889-895
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• 2011

영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor:이하 PMLSM)는 구조적으로 간단하며 고속화 고추력화 등의 많은 장점을 가지고 있지만 전기자 권선부의 슬롯-치 구조로 인한 코깅력과 단부효과에 의한 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치 할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 PMLSM의 가동자에 보조극의 설치를 제안하였다. 또한 2차원 유한요소법(Finite Element Analysis)을 이용하여 단부 코깅력이 최소가 되는 보조극의 형태를 설계하고 전기자의 권선 방식에 따른 단부 코깅력 특성을 비교하였다.

• 한국환경과학회지
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• 제18권2호
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• pp.221-230
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• 2009

In this study, a river basin with a lot of measured data such as water level, flow rate, current speed, and sediment rate from the past to now was selected and geometrical shape of a pier was re-analyzed, in order to study the effects of the flow around the pier area as well as the riverbed alternation characteristics. A finite element mesh of the entire river was prepared, and via parameter revision, the section that the pier has influence on was decided, to analyze the shape of the pier using RMA-2 and SED2D-WES models. With regards to the section that the pier has influence on, analysis was done on the four pier shapes, namely circle, square, rectangle, and octagon. The results showed that the shape with the least influence around the pier around is the octagon, followed by circle, rectangle, and square, showing the different geometrical effects that the shapes have on the pier. Furthermore, it was shown that the distribution of sediment concentration had effect from about (+) 110 m of the upstream to about (-) 130 m of the downstream, from the pier installation point. Also, it was shown after analyzing drag forces for different sediment particle distributions that the shape with the greatest drag is the octagon, followed by circle, square, and rectangle.

• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.598-603
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• 2012

Despite the high efficiency and eco-friendly of Household Fuel Cell System it has hardly obtained popularity mainly due to its high prices. In order to encourage use of the system prices and operational expenses need to become economical. In this study, optimization through simulation was conducted to find out the optimal operational condition. As a result of simulation the system is operated with DSS operation from 5 O'clock to 19 O'clock for 14 hours at the constant output of 0.4kW to maximize reduction of energy rate. this DSS operation condition can reduce 200,000 won of energy rates in 35 pyoung apartment for a year. And, we can know that starting time of DSS operation don't effect to energy rates through the simulation. Furthermore, the household fuel cell system with the rated output of 1kW should be reduced to 0.4 - 0.6kW which can promote installation of household Fuel Cell System. Now, the household fuel cell system don't have been used widely due to economical efficiency. but, in the near future, Fuel Cell will be used to household by decrease of LNG price caused by development of shale gas.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.38-43
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• 2017

The role of current lead in high-temperature superconducting synchronous machine (HTSSM) is to function as a power supply by connecting the power supply unit at room temperature with the HTS field coils at cryogenic temperature. Such physical and electrical connection causes conduction and Joule-heating losses, which are major thermal losses of HTSSM rotors. To ensure definite stability and economic feasibility of HTS field coils, quickly and smoothly cooling down the current lead is a key design technology. Therefore, in this paper, we introduce a novel concept of a cooling anchor to enhance the cooling performance of a metal current lead. The technical concept of this technology is the simultaneously chilling and supporting the current lead. First, the structure of the current lead and cooling anchor were conceptually designed for field coils for a 1.5 MW-class HTSSM. Then, the effect of this installation on the thermal characteristics of HTS coils was investigated by 3D finite element analysis.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권4호
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• pp.210-220
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• 2002

We analysised the effect of harmonics on electric machines of substation power system barred on quantitatively measured harmonics and proposed the methods for prevention of harmonics through checking on transformer, rectifier and cable's capacities against harmonics with reference to KEPCO's electricity service standard. In order to analysis harmoninics of silicon rectifier that is power source in DC substation, computer simulations for a substation with TR of high voltage distribution switchboard are performed. Simulation results show that the total harmonic distortion factor becomes smaller for TR primary and receiving points in order rather than silicon rectifier which is harmonic generation source so that the harmonics generated frets each rectifier are outflowed to power supply and high voltage distribution switchboard The result of higher distortion factors of voltage and current for rectifier with 100% load than those with 50 % and 30% indicates that the waveform of voltage and current for the real substation power system at the office-going and the closing hours with heavy loads might be more distorted. As proposed methods for harmonic reduction, the conventional 6 pulse-type for substation is required to be replaced by 12 pulse-type for reduction of 5th and 7th harmonics. The active filter rather than the passive filter is more effective due to severe variance of rectifier loads, but the high cost is price to be paid. In view of installation area and costs, the use of 12 pulse-type transformer is desirable and then the parallel transformer and the rectifier within the substation must be replaced at the same time. Other substations with parallel feeder can use 6 pulse-type transformer.