• 드라이브 ㆍ 컨트롤
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• 제9권2호
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• pp.8-14
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• 2012

Electro-hydraulic spring return actuator(ESRA) is utilized for air conditioning facilities in a nuclear power plant. It features self-contained, hydraulic power that is integrally coupled to a single acting hydraulic cylinder and provides efficient and precise linear control of valves as well as return of the actuator to the de-energized position upon loss of power. In this paper, the algebraic equations of ESRA at steady-state have been developed for the analysis of static characteristics that includes control pressure and valve displacement of pressure reducing valve, flow force on flapper as well as its displacement over the entire operating range. Also, the effect of external load on piston deviation is investigated in terms of linear system analysis. The results of static characteristics show the unique feature of force balance mechanism and can be applied to the stable self-controlled mechanical system design of ESAR.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.142-147
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• 2008

This paper reports an analysis of self-pressurization in a closed cryogenic liquid storage system and its comparison with experimental data using liquid nitrogen. Partial equilibrium model(PEM), revised thermodynamic analysis of homogeneous model, has been applied for the pressurization in a closed tank. The vapor and liquid bulk temperature and the liquid-vapor interface temperature are separately calculated as their own representative values in this analysis. The analysis results of the partial equilibrium model are compared with the experimental data and other preceding homogeneous temperature models for validation.

• 디지털융복합연구
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• 제14권7호
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• pp.193-200
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• 2016

최근 들어 가정 내 태양광과 에너지저장시스템을 도입하여 에너지 자립도를 높이고자 하는 기술 개발이 활발히 이루어지고 있다. 낮에 생산된 전기를 에너지 저장 시스템에 충전해 두고 전기요금이 높을 때 사용함으로써 효율적인 에너지 관리를 수행할 수 있다. 국내에서는 아직까지 가정용 실시간 요금제가 이루어지고 있지 않지만 누진제 상의 일정 목표까지 전기 사용량을 낮출 수 있다. 가정 내 태양광을 도입하기 위해서는 전력 변환장치인 PCS를 필요로 한다. PCS는 직류로 생산된 전력을 교류로 변환하여 사용하고 에너지 저장 시스템의 충방전을 수행하도록 한다. 에너지 자립형 스마트 홈 시스템은 태양광, 에너지저장시스템에 대한 일반인들의 관심이 높아지면서 해외를 중심으로 시장이 형성되는 단계이다. 본 논문의 결과물은 실환경에 설치되어 검증을 수행하였으며 실시간 요금제를 가정하여 에너지 절감 효과를 분석하였다.

• Journal of Preventive Medicine and Public Health
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• 제53권1호
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• pp.15-25
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• 2020

Objectives: The purpose of this study was to investigate the health effects of air conditioning use during the 2018 heat wave in Korea, included the highest temperature ever recorded in the nation. Methods: The participants in this study were 1000 adults aged 19 years and older recruited from across Korea. The participants were asked about their experience of symptoms of various diseases, disruptions of their daily lives, and use of air conditioning during the heat wave. The associations between air conditioning use during the heat wave and health outcomes were analyzed using the chisquare test and multiple logistic regression models. Results: Among participants who lacked air conditioning in the main space where they spent time outside the home, 33.9%, 8.1%, 43.5%, and 19.4% experienced symptoms of heat-related, cardiovascular, nervous system diseases, and air-conditioningitis, respectively. In comparison, participants who did have air conditioning outside the home experienced the same symptoms at proportions of 21.0%, 1.9%, 26.8%, and 34.2%, respectively (p=0.027, 0.007, 0.007, and 0.023, respectively). Among participants who had no air conditioner at home, 10.0% were absent from school or work due to the heat wave. In contrast, among participants who had an air conditioner at home, only 3.7% were absent as a result of the heat wave (p=0.007). Conclusions: When air conditioning was not used at home or in the main space where participants spent time outside the home during the 2018 heat wave, adverse health effects were more prevalent, but the risk of air-conditioningitis was reduced.

• 설비공학논문집
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• 제5권4호
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• pp.265-277
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• 1993

Recently, underground transmission system is growing continuously according to the electric power demand increase in the downtown area. Even if domestic cable makers are manufacturing 154kV oil filled cable and joint, the design technology of cable-joint has not been fully self-reliance. This study is aimed at the detail heat transfer analysis of 154kV cable-joint. So, that is cut into the five sections in order to analyze a conjugate natural convection in two dimensional $r-{\theta}$ coordinate. The streamline and temperature distributions are obtained for each sections. Also the changes of those are analyzed with respect to the variation of transmission currents and cable-joint surface heat transfer coefficients. The same analyses are also shown in view point of the maximum temperature of conductor and local equivalent conductivity.

• 설비공학논문집
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• 제7권3호
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• pp.450-460
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• 1995

A modified circulating fluidized bed heat exchanger under severe fouling condition is developed. The effects of fouling deposits on the performance of a heat exchanger are investigated. The principle and operating characteristics of a circulating fluidized bed heat exchanger are dicussed. A modified circulating fluidized bed heat exchanger shows more stable operating than the other circulating fluidized bed heat exchanger. The characteristics of self cleaning and heat transfer enhancement of a circulating fluidized bed heat exchanger are studied. The movement of spherical particles in a tube is visualized and heat transfer enhancement and scale reduction mechanism by particles are investigated.

• 설비공학논문집
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• 제18권3호
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• pp.262-269
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• 2006

Formaldehyde and total volatile organic compounds (TVOC) from building materials have been known as main causes of IAQ problem in Newly-Constructed Multi-Family Houses. Because Multi-Family Houses are built in large quantities in a similar manner, inappropriate selection of building materials and method will detrimental affect IAQ. This research aims to identify major causes of Indoor Air Pollutants in Multi-Family Houses, by constructing Mock-Up & One-Room House. As a result, self leveling concrete, door, and furniture construction is a major cause of indoor formaldehyde increase, and tile bond is TVOC, and urethane water proof is Etylbenzene, and Xylene.

• 대한치과보철학회지
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• 제46권5호
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• pp.535-543
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• 2008

최근의 레진 접착시스템은 단계를 줄이고 적용과정을 간편화시키는데 주력하고 있으며, 치면에 bonding 및 conditioning 과정 없이 바로 적용 가능한, one-step의 새로운 자가 접착 레진시멘트 (self-adhesive resin luting cement)들이 소개되어 임상에 사용되고 있다. 이에 본 연구의 목적은 자가 접착 레진시멘트와 기존의 레진시멘트의 상아질에 대한 전단 결합 강도를 비교해보고, 자가 접착 레진시멘트 적용시 치면의 식각 처리 여부가 전단 결합 강도에 미치는 영향에 관하여 알아보고자 하는 것이다. 본 연구를 위해 최근 6개월 내 발치된 비교적 건전한 성인의 대구치 45개를 아크릴릭 레진으로 매몰한 다음, 800 grit SiC연마지로 연마를 시행하여 상아질을 노출시켰다. 15개의 치아를 한 군으로 하여, 세 가지 실험군으로 분류하였다. Group 1) 치면에 아무런 전처리 없이 RelyX Unicem 접착. Group 2) 치면에 인산 산부식 처리 후, RelyX Unicem 접착, Group 3) 치면에 Syntac primet + Syntac adhesive + Heliobond 처리 후 Variolink II 접착. 전처리가 완료된 치아 시편 위에 플라스틱 튜브 (직경 3 mm, 높이 3 mm)를 고정한 다음, 제조사의 지시에 따라 각 레진 시멘트를 혼합하여 링 안을 채우고, 광중합을 시행하였다. 접착이 완료된 시편은 $37^{\circ}C$ 항온수조 (증류수)에서 24시간 동안 보관 후, 만능 시험기를 이용하여 1mm/min의 cross head speed로 결합강도를 측정하였으며, 확대경 하에서 파절 양상을 분류 관찰하고, 주사전자현미경을 이용하여 미세구조를 관찰하였다. 측정결과는 SPSS WIN 12.0 프로그램을 사용하여 분석하였으며 다음과 같은 결과를 얻었다. 1. RelyX Unicem의 상아질에 대한 전단결합강도는 Variolink II와 유의한 차이를 보이지 않았다. 2. 상아질에 대한 인산 산부식 처리는 RelyX Unicem과의 전단결합강도를 낮게 하였다. 3. RelyX Unicem과 Variolink II에서는 혼합 파절의 비율이 컸으며, 전단결합강도가 낮았던 인산 산부식 처리 후 RelyX Unicem을 접착한 경우에서는 전체 시편에서 접착성 파절이 관찰되었다. 결론으로 말하면, 자가 접착 레진시멘트와 기존의 레진시멘트의 상아질에 대한 전단결합강도는 유의한 차이를 보이지 않으며, 인산 산부식 처리는 상아질에 대한 자가 접착 레진시멘트의 전단결합강도를 감소시킨다.

• 한국보건간호학회지
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• 제14권1호
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• pp.12-25
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• 2000

The purpose of this study was to determine the effects of aerobic rhythmical exercise program on $VO_2$ max, leg strength, grip strength, flexibility, exercise self-efficacy and quality of life in elderly. This quai-experimental study was designed as a non-equivalent control group pretest-posttest study. 36 subjects, aged between 65 and 73 years who have normal cognition. sensory function and cerebellum function participated in this study. 19 experimental group subjects participated aerobic rhythmical exercise program. Aerobic rhythmical exercise program was developed on the basis of calisthenics, stretching, aerobic exercise, Korean traditional dance and music by the author. The program consisted of approximately 1 hours of exercise, 3 times a week for 9 weeks. During 1 hours workout, there were 15 minutes of warm-up dancing, 35 minutes of conditioning dance and 10 minutes of cool-down dancing. The intensity for the conditioning phase was between $40\%\;and\;60\%$ of age adiusted maximum heart rates. The $VO_2$ max, grip strength, leg strength, flexibility, exercise self-efficacy and quality of life were measured prior to and following the experimental treatment. Data were analyzed with $x^2-test$, t-test, mean, standard deviation. percentage of change and ANCOVA test using SAS program. Results were obtained as follows. 1. The $VO_2$ max of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=7.76, p=0.008). 2. The grip strength of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=4.61, p=0.039). 3. The leg strength of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=9.29, p=0.000). 4. The was no significantly difference of flexibility between experimental and control group 5. The self-efficacy of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=43.40, p=0.000). 6. The quality of life of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=8.91. p=0.005). The results suggest that aerobic rhythmical exercise program can improve $VO_2$ max, grip strength. leg strength. exercise self-efficacy and quality of life elderly. Thus. aerobic rhythmical exercise program was a useful nursing intervention for elderly.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1990년도 추계학술발표회논문집
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• pp.57-62
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• 1990

This paper describes the development and testing of a degitial controller for heat-ing ventilating and air-conditioning system. The controller uses properational-integral control action and self tunes to provide the Zigeler-Nichols when given a step input. The algorithm has been simulated fas static pressure.