• 한국전기전자재료학회논문지
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• 제31권7호
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• pp.469-474
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• 2018

In this study, the capacity and FTIR of polycarbonate film that was degraded for 2, 4, and 8 h in a thermostat at $180^{\circ}C$ was measured. The results of this study are as follows. It was found that the capacity decreased with increasing degradation time and frequency. This findings suggest that the attraction between molecules and amorphous polycarbonate increased because it contains the ketone group (-C=O-) and the chain of dioxides group (-O-R-O-). Measurement by FTIR found that the time of thermal degradation has a smaller impact because the transmutation or variation of the material does not occur. Measurement by SEM magnified 1,000 times found that a longer thermal degradation time results in thermal decomposition of the specimen's particles.

• 설비공학논문집
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• 제14권7호
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• pp.607-616
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• 2002

This study has been conducted to evaluate the applicability of the control method in the dehumidification-integrated radiant floor cooling system in terms of stability of the room air temperature and the control variables through experiments. To do this, the relationship between the control variables in preventing floor surface condensation is first analyzed and the control method is predetermined through simulations. The results are as follows. First, it is necessary to determine the operation status of the dehumidification system according to the relationship between floor surface temperature and dew point temperature in the conditioned space. Second, outdoor reset with indoor temperature feedback control is better than on/off bang-bang control with respect to temperature stability in controlling the room air temperature and the possibility of energy savings. Finally, the humidity sensor can be located with the current thermostat in that there are small differences in absolute humidity in vertical distribution.

• 대한기계학회논문집A
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• 제20권12호
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• pp.3748-3758
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• 1996

This study is to investigate experimentally relationships between the impact energy and moisture absorption characteristies vs.the residual bending strength with the variation of stacking seqences. When Carbon-fiber reinforced plastics(CFRP) impact-induced laminates are subjected to the high temperatures and hygrothermal effects, it is found that what CFRP laminates are impacted by a steel ball (5 mm in diametar) ; thus, the generated delamination is observed by the ultrasonic microscope. And the residual bending strength is evaluated by a three-point bending test. Also, a thermostat is used in test with the unimpacted and impacted specimens for the moisture experimentaiton. The percision electro lever scles is used to measure the moisture content(1/10, 000g).

• 한국정밀공학회지
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• 제12권4호
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• pp.135-142
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• 1995

Recently, the analysis of microcutting with submicrometer depth of cut is tried to get a more high quality surface product, but to get a valuable result another method instead of conventional finite element method must be considered because finite element method is impossible for a very small focused region and mesh size. As the alternative method, Molecular Dynamics or Statics is suggested and accepted in the field of microcutting, indentation and crack propagation. In this paper using Molecular Dynamics simulation, the phenomena of microcutting with subnanometer chip thickness is studied and the cutting mechanism for tool edge configuration is evaluated. As the result of simulation the atomistic chip formation is achieved.

• 한국환경농학회지
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• 제8권2호
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• pp.142-147
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• 1989

환기에 의한 열손실과 지중으로의 열손실을 제외하면 그린하우스의 열손실은 피복재를 통한 열전도 및 열복사에 의해 일어난다. 따라서 동일한 환경조건 하에서 프라스틱 필름으로 하우스를 만들 때 하우스의 보온력은 피복재를 통한 열손실 속도의 크기에 지배받는다. 본 연구에서는 프라스틱 필름을 통한 상대적 열손실 속도를 측정함으로써 하우스의 보온력을 예측할 수 있는 간단한 장치와 방법을 고안하였다. 육면체 형태의 frame을 만들어 측정용 필름으로 둘러싸서 밀폐된 box를 만들고 thermostat로 조절되는 heater와 box 내부의 온도변화를 감지 기록하기 위한 온도 Probe를 내부에 장치하였다. box 내부와 외부간에 일정한 온도차를 이루게 한 다음 (10$^{\circ}C$내외), 그 온도 차이가 유지되도록 일정한 양의 열을 10회에 걸쳐 단속적으로 (그리고 자동적으로) 투입함에 있어서 그 투입 에 요한 총 시간, 즉 항온유지시간을 재고, 이 항온유지 시간의 역수로서 필름을 통한 상대적 열손실 속도를 측정하였다. 동일한 두께의 필름인 경우에 상대적 열손실 속도는 PE>EVA>PVC의 순으로 감소하였고, silica gel보온재가 첨가된 필름의 열손실 속도는 보온재 무첨가 필름보다 역시 감소함을 보여주었다. 이러한 측정결과는 재질에 따른 필름 보온성에 관한 이미 상식화한 사실과 부합되는 것으로서, 본 고안 장치가 여러 가지 상품화된 하우스용 필름의 선별에 쉽게 이용될 수 있음을 시사한다.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.534-544
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• 2017

본 연구는 해양현화식물인 잘피 추출물의 화장품소재로서 활용가능성을 확인하기 위해 항산화 효능을 확인하였고 잘피 추출물이 함유된 에멀션의 시간과 보관 온도에 따른 제형 안정성을 확인하였다. 잘피를 용해하여 DPPH(1,1-Diphenyl-2-picrylhydrazy) radical assay와 SOD (superoxide dismutase)-like activity를 통해 항산화 시험을 진행하였으며 잘피 추출물이 함유되어 있는 에멀션의 pH, 점도를 측정하고 Turbiscan LAB을 이용하여 입자의 분산상을 확인하였다. 에멀션은 28일 동안 $25^{\circ}C{\pm}1^{\circ}C$, $40^{\circ}C{\pm}1^{\circ}C$ 항온조에 보관하여 일주일 간격으로 측정하였다. 그 결과 잘피 추출물은 5.00 mg/ml농도에서 86.21%의 DPPH radical 소거활성을 확인하였고 99.24%의 SOD 유사활성을 나타내었으며 농도 의존적으로 항산화 효과가 있는 것을 확인 하였다. 에멀션의 pH, 점도, 입자 안정성을 28일 동안 각 항온조에 보관하여 측정하였을 때, 보관 기간에 따른 물성의 변화가 미미하여 잘피 추출물이 함유된 제형은 시간과 보관 온도에 따라 안정한 것으로 확인되었다. 상기의 결과를 통해 70% 에탄올로 추출한 잘피 추출물은 피부노화를 예방하기 위한 항산화 화장품 소재로서 응용이 가능할 것으로 사료된다.

• 대한기계학회논문집B
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• 제36권1호
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• pp.31-36
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• 2012

군용 차량은 일반 차량에 비하여 높은 기동 성능 및 정숙성을 요구한다. 또한 최소의 연료 보급으로 최대의 작전 수행 능력을 보유하고 있어야 한다. 시리즈 하이브리드 자동차의 경우 모터만을 이용하여 차량을 구동하므로, 정숙성이 뛰어나고 초기 기동 토크가 커 구동 성능이 뛰어나다. 또한 하이브리드화를 통하여 연비 향상 효과를 얻을 수 있다. 이와 같은 시리즈 하이브리드 차량의 경우 배터리 SOC 와 차량의 주행 상태에 따라 엔진과 발전기로 이루어진 발전 시스템에서 전기를 생산하여 차량 구동에 이용하거나 배터리를 충전한다. 발전 시스템의 작동 여부와 작동 영역을 결정하는 것이 시리즈 하이브리드 차량의 주행 전략이며 이 주행전략에 따라 연비 성능에 차이가 난다. 본 연구에서는 Thermostat, Power-Follower, Combined 주행 전략을 비교/평가 하였으며 새롭게 제안한 Combined 주행 전략을 통하여 기존 차량 대비 37%의 연비 향상 효과를 얻을 수 있었다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권3호
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• pp.283-288
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• 2005

A portable primary inductance standard set that includes a Maxwell-Wien bridge and a 10 mH standard inductor installed in a thermostat has been developed at KRISS. Two auxiliary resistance capacitance networks (analogous to a 'Wagner ground') provide excellent stability of the bridge balance and impose less strict requirements on the components of these networks. Removable capacitance and ac-dc resistance standards used in the bridge arms made it possible to reproduce 10 mH and 100 mH inductance values in the frequency range of 500 Hz to 3 kHz. From investigations of this standard and preliminary comparison with VNIIM (D. I. Mendeleyev Institute for Metrology), the results have demonstrated that the bridge can be used as a part of the transportable inductance standard with a measurement uncertainty within (1-3) $\mu$H/H at frequencies of 1 kHz and 1.6 kHz. The application of the bridge as a constituent part of the transportable standard gives us an opportunity to eliminate the influence of the standard inductors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3958-3971
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• 2016

With Internet of Things (IoT) technology, home environment becomes smarter than ever. Not only smart devices such as smart phone or smart TV, but also various IoT devices including sensor, smart thermostat, and smart scale has now become very common on the market. These devices have connectivity to the Internet, so that user can read data from the device or control the device using Internet technology. However, due to diversity of smart home requirements, device collaboration in smart home remains a challenging task still. Usually smart home is built with various technologies to fulfill its own purpose, and these purposes cover very wide area from controlling low-power sensor devices to controlling high-performance devices like smart TV and smart phone. This variety of smart home requirements makes smart home very complicated due to mixed network architecture, protocol and technology. In this paper, a framework to enable managing and collaborating heterogeneous IoT devices in smart home environment is proposed. Several programming models are defined in the proposed framework to make application development for heterogeneous devices more intuitive. The proposed framework has been implemented as a web service, and a case study with real-world smart home IoT devices is presented.

• 설비공학논문집
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• 제16권5호
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• pp.421-429
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• 2004

In Korea, the radiant heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. According to the recent improvement of living standard of residential buildings, the requirement of the thermal comfort and energy saving in heating system has been raised. Until now, the radiant floor heating system has been controlled by room thermostat installed in the living room, but for better thermal comfort, an individual room control method is adopted as an alternative. Therefore, it is necessary to evaluate the control performance between the current control method and the individual room control method. In this study, the control performance between the two systems is evaluated through the field experiment. And the control performances of room air temperature and energy performances are analyzed through the simulation using TRNSYS. Firstly, the simulations are performed in the various outdoor conditions and the flow rates and the simulation results are analyzed for the control performances. Also, to evaluate the energy performance, the simulations are performed under the operating conditions in which the set-point of the room air temperature is fixed or changed according to the schedule of occupancy, and the simulation results are analyzed between the two methods.