• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.127-133
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• 2012

This paper is an experimental study on the freezing protection valve used for solar water heating, air-conditioning systems, and plumbing systems. When the phase change occurs from liquid to solid, most of the substances except water volumetrically shrink. And referred to as PCM(Phase Change Material) a substance with such properties, the phase change temperature varies depending on the material. To prevent the freezing of the plumbing system, such as air-conditioning system in the winter season, we developed a several types of freezing protection valve using PCM whose freezing temperature are $2-4^{\circ}C$. The working principle of the freezing protection valve is that the fluid inside the pipe is released to prevent the system-collapse when fluid temperature reaches the freezing temperature of the PCM. And then the valve is closed and returned to the original position automatically when the temperature of the operating fluid rises. In this paper, the operating temperatures, discharge flow rate and the response characteristics of the valve during the operation are tested and investigated. From the results of this research the freezing protection valves employing PCM are expected to be commercialized in the near future.

• Corrosion Science and Technology
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• 제14권3호
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• pp.120-126
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• 2015

The usage of bending products recently have increased since many industries such as automobile, aerospace, shipbuilding, and chemical plants need the application of pipings. Bending process is one of the inevitable steps to fabricate the facilities. Induction heat bending is composed of compressive bending process by local heating and cooling. This work focused on the effect of induction heat bending process on the properties of ASME SA312 Gr. TP304 stainless steel pipes. Tests were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. In order to determine intergranular corrosion resistance, Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test and ASTM A262 practice A and C tests were done. Every specimen revealed non-metallic inclusion free under the criteria of 1.5i of the standard and the induction heat bending process did not affect the non-metallic inclusion in the alloys. Also, all the bended specimens had finer grain size than ASTM grain size number 5 corresponding to the grain sizes of the base metal and thus the grain size of the pipe bended by induction heat bending process is acceptable. Hardness of transition start, bend, and transition end areas of ASME SA312 TP304 stainless steel was a little higher than that of base metal. Intergranular corrosion behavior was determined by ASTM A262 practice A and C and DL-EPR test, and respectively step structure, corrosion rate under 0.3 mm/y, and Degree of Sensitization (DOS) of 0.001~0.075% were obtained. That is, the induction heat bending process didn't affect the intergranular corrosion behavior of ASME SA312 TP304 stainless steel.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.84.1-84.1
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• 2015

Recent years in particular in Korea see intensive interests in a deep geothermal engineering and its application in different uses as far as from direct uses to power generation sectors, that are achieved by harnessing hot energy sources from the earth. For instance widespread interest has been generated because the geothermal energy is the source that one extracts it for more than 20 hours per day and for about 30 years of an operation of the plant, which enables to give base load as for heating as well as an electric generation. In retrospect, shallow geothermal energy using heat pumps is commonplace in Korea while the deep geothermal is in the early stage of the development. Geothermal energies in view of the way of extracting heat are mainly categorized into several types such as a single well system, a hydrothermal system, an enhanced geothermal system (EGS) etc. In this talk, this speaker focuses on the thermo-fluid engineering of the single well system by introducing the modeling in order to harness hot fluid that is thermally balanced with the fluid of an injection well, which provides a challenge to assess the life time of the well. To avoid the loss of the temperature in producing the hot fluid, a specialized pipe or a borehole heat exchanger has been designed, and its concept is introduced. On the other hand, a binary system or an organic Rankine cycle, which provides the methodology to convert the heat into an electricity, is briefly introduced. Some experimental results of the binary system which has been constructed in our lab will be presented. Lastly as for the future direction, some comments for the industrialization of the deep geothermal energy in this country will be discussed.

• 한국산업융합학회 논문집
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• 제9권1호
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• pp.51-59
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• 2006

The study is diagnosis about fatigue failure phenomenon of heating coil spring (sup9) and heat treatment method that is used to crusher. Because more than 80~90% of damage announcement of breakdown of machine and construction is been caused in fatigue present state, fatigue failure became important leading person at design. Calculated design load is imposed repeatedly that fatigue breakdown is safe. Is phenomenon that change load is imposed in the construction continuously. Used coil spring applies heat 30minute by Quenching temperature $860^{\circ}C$ if see manufacturing process and temperature of gasoline of $50^{\circ}C$ keep after quench that know tempering a $460^{\circ}C$ 90minute a product be. If doto apply heat $950^{\circ}C$ material at rolling process historically before quenching, austenite formation clay pipe being done AGS(Austenite Grain Size) by 2.5~4 become. Apply heat quenching 30minute by $820^{\circ}C$ by improvement method and after quench that keep $50^{\circ}C$ in oil tempering if do $450^{\circ}C$, 90minute spring ideal formation sorbite formation of the river form and condition that satisfy most more than AGS 7 appeared. Also, we can secure authoritativeness through MT since shot peening processing.

• Journal of Biosystems Engineering
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• 제35권1호
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• pp.46-52
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• 2010

The temperature of root zone was known as an important factor for the growth of crops and reduction of energy in greenhouse. The purpose of this study was to design the apposite inflow of calories per the unit area by comparison of temperature in the warmed and non-warmed soil. The energy needed for soil warming about pipe length showed the change of temperature on inflow and outflow as $2^{\circ}C{\sim}3^{\circ}C$(average $2.5^{\circ}C$). Therefore, the inflow per the unit hour was 3,450, 57,5 kcal/$h{\cdot}m^2$ on soil heating respectively. The non-warmed soil temperature in greenhouse made a difference by depth and it was partially affected inner temperature under 15 cm, but it was not above 15 cm. The soil temperature would be raised over $5^{\circ}C$ than non-warmed soil to increase effect of soil warming. Therefore, the inflow per the unit area that should be provided was about 100 kcal/$h{\cdot}m^2$.

• 지질공학
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• 제26권4호
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• pp.461-471
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• 2016

수주지열정의 지하수 유동 및 지열 이동 현상을 모사할 수 있는 수치 모델링 기법을 제시하기 위하여 열-수리학적 모델인 TOUGH2를 기반으로 한 모듈을 개발하였고 두 유형의 수주지열정에서의 냉방 및 난방 운영을 수치 모의하였다. 수치 모델링 결과들은 수주지열정의 냉난방 운영이 주변 지층 및 지하수와의 열교환 및 유체 혼합에 크게 영향을 받으며, 특히 PVC 또는 PE 파이프 내부와 수주지열정 내부에서 서로 반대방향으로 유동하는 유입수와 유출수 간의 열교환이 중요한 요소임을 보여준다. 또한 본 연구에서 개발 및 제안된 수치 모델링 기법이 수주지열정의 내부 구조 및 유체 유동과 열 이동 현상을 합리적으로 모사할 수 있음을 보여준다. 이러한 수치 모델링 기법은 수주지열정의 설계, 시공 및 운영 단계에서 열교환 성능을 정량적으로 분석할 때 유용하게 활용될 수 있을 것으로 기대된다.

• 한국농공학회논문집
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• 제47권3호
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• pp.29-37
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• 2005

This study was carried out to file up structural design data for optimizing Pleurotus eryngii growing houses. Design data are including current farm status of Pleurotus eryngii growing houses in the aspect of structural configuration as well as environmental conditions to be controlled and maintained inside. A structural analysis was performed for the on-farm structures as well as some structures modified and suggested through field survey and analysis. The results are summarized as follows. According to the results of status analysis, Pleurotus eryngii growing houses were categorized as arch-roofed simple type and sandwich panel type. Though the size of Pleurotus eryngii cultivation facilities were considerably diverse, the basic dimensions of Pleurotus eryngii cultivation facilities showed relatively similar pattern: more or less of 20m of length, $6.6\~7.0m$ of width, $4.6\~5.0m$ of peak height, $1.2\~1.6m$ of bed width, and 4 layers of bed. In the aspect of spatial use of cultivation facilities, suggested models were shown to be mostly reasonable in the aspect of heating and cooling, micro-meteorological stability, land use efficiency per unit floor area, etc.. Especially, the standard models suggested so far were thought to be not efficient in its surface area and spatial volume per unit floor area as well as its uneffective structural design in the area around ceiling. In the results of structural analysis for the models suggested through this study by using those section frames to be found on farms, the panel type structures of both single span and double span were estimated to be over designed, whereas arch-roofed pipe houses were mostly found to be under-designed.

• 센서학회지
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• 제25권5호
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• pp.344-348
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• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• 한국산업융합학회 논문집
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• 제23권1호
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• pp.93-100
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• 2020

In this paper, soilless cucumber cultivation was investigated, fermented fertilizer to increase the cucumber yield was considered, and the greenhouse temperature control system for cucumber cultivation is developed. To do this, perlite was proposed to replace soil as growth medium. Fermented cows and pigs manure was proposed as plant fertilizer. Combination of fan, water sprinkler, and pipe heating system was proposed to control the greenhouse temperature. However, because this research was conducted during the summer, the greenhouse system observed in this study only focused on variations in the flow rate of the water sprinkles used. The experimental result shows that soilless culture in the greenhouse could be an alternative to traditional field production for high-value vegetable crops. Furthermore, application of fermented fertilizer of 10% could enhance the growth and increase the yield and quality of crops. The proposed sprinkler flow rate is best suited for cucumber crop with the best thrives was 0.846 kg/s.

• 인터넷정보학회논문지
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• 제9권6호
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• pp.117-125
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• 2008

유비쿼터스 응용 시스템에 대한 관심의 증대와 함께 소형화된 임베디드 컴퓨팅 시스템의 필요성은 커지고 있다. 이러한 가운데 ARM 임베디드 프로세서는 기능의 우수성과 높은 활용도로 인해 임베디드 시스템 시장에서 높은 점유율을 보여주고 있다. 본 논문에서는 ARM 마이크로컨트롤러를 이용해 RTD-1000 컨트롤러 구성과 개발을 위한 최적의 방법을 제안하였다. 기존 RTD-1000은 케이블의 단선, 단락, 파손 등의 진단이 가능한 TDR를 탑재하여 구리선을 삽입한 감지관의 누수 및 누유, 파괴 등을 원격으로 감지할 수 있는 기기이다. 실제로 시공되어 현장에서 운영되고 있는 RTD-1000은 시스템 운영에 필요한 범위에 비해 리소스 낭비가 크고 그에 따라 구축비용이 높다는 단점을 가지고 있다. 또한, 발열이 심해 별도의 냉각장치가 요구되며, 하드 디스크와 같은 보조저장장치의 사용으로 고장 발생율과 전류의 소비가 커지는 등의 문제점을 야기하였다. 본 논문에서는 도출된 문제점의 해결 방법으로 ARM 마이크로컨트롤러 기반의 RTD-1000A 임베디드 시스템을 제안하고 시뮬레이션 하였다.