• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.57-60
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• 2007

A fluidized bed reactor made of quartz with 0.055 m I.D. and 1.0 m in height was employed for the thermocatalytic decomposition of methane to produce $CO_{2}$ - free hydrogen. The fluidized bed was proposed for the continuous withdraw of product carbons from the reactor. The methane decomposition rate with the carbon black N330 catalyst was quickly reached a quasi-steady state rate and remained for several hour. The methane and propane mixture decomposition reaction was carried out at the temperature range of 850 - 900 $^{\circ}C$, methane and propane mixture gas velocity of 1.0 $U_{mf}$ ${\sim}$ 3.0 $U_{mf}$ and the operating pressure of 1.0 atm. Effect of operating parameters such as reaction temperature, gas velocity on the reaction rates was investigated. The produced carbon by the methane decomposition was deposited on the surfaces of carbon catalysts and the morphology was observed by SEM image.

• 대한가정학회지
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• 제32권5호
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• pp.135-142
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• 1994

This research was undertaken to investigate the state of lunchbox preperation and the opinion of operating school lunch program. The subjects were 180 mothers and their children in the 6th grade of elementary school in Seoul, where a school lunch program were not operated. The results were summarized as follows ; The age of mothers were from 30's to 40's and among them over 80% graduated from a high school and 26.1% had a job. 88.9% of mothers prepared lunchbox everytime and main dish was mostly bab. The average time spent in preparing meal for one day and lunchbox were 1 hour and 58 minutes, and 28.6 minutes respectively. The number of side dishes cooked per day and for lunchbox were 9 and 3, respectively. The side dishes for lunchbox were kimchi, dried layer, ham, dried squid, egg in decreased order, which were similar to preference of children. Animal protein foods were mainly used in lunchbox than vegetables. On preparing lunchbox, mothers considered preferance, nutrition, convenience of cook, economic, appearance of food in decreased order. 92% of mothers and 75% of their children approved of operating school lunch program, and the reason, answered by their mothers, was nutritional balance of their children. In conclusion, it's needed to operate of school lunch program for optimal nutritional intake and growth of children.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.97-100
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• 2007

A fluidized bed reactor made of quartz with 0.055 m I.D. and 1.0 m in height was employed for the thermocatalytic decomposition of methane to produce $CO_2$ - free hydrogen . The fluidized bed was proposed for the continuous withdraw of product carbons from the reactor. The methane decomposition rate with the carbon black N330 catalyst was quickly reached a quasi-steady state rate and remained for several hour. The methane and propane mixture decomposition reaction was carried out at the temperature range of 850 - 900 $^{\circ}C$, methane and propane mixture gas velocity of 1.0 $U_{mf}$ ${\sim}$ 3.0 $U_{mf}$ and the operating pressure of 1.0 atm. Effect of operating parameters such as reaction temperature, gas velocity on the reaction rates was investigated. The produced carbon by the methane decomposition was deposited on the surfaces of carbon catalysts and the morphology was observed by TEM image.

• Journal of Biosystems Engineering
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• 제3권2호
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• pp.126-132
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• 1978

This study was carried out through the survey questionaries in order to get the information for proper operating technique of the two-wheel tractors which are widely used in the farm, and investigated various accidents which occurred during the operation of two-wheel tractors for farm works in 7 Provinces of Korea. The summarized results are as follows ; 1. Annual accident frequency of the two-wheel tractor was 2.07 times, and the average rate of accident was 0.72 times per hour. Its value was the largest in the pre-operations , and the smallest in the threshing operation. 2. The accident distribution according to each month was nearly propertional to the operating hours of the two-wheel tractor. More than 60 % of total accident was concentrated during the rice transplanting and harvesting season. 3. The careless accident was more than 50% of total accident , and inevitable accident about 18% . The rate of careless accident showed the highest in pre-operation such as engine starting, check, and adjustment, and belt change. 4. The serious wounded operator was 7.1 % to total wounded operator , and about 50 % of accident of casualties to operators occurred during haruling operations. 5. The amount of casualties to property was range of 1,000 to 10,000 won, and annual total amount per unit tractor could be estimated to be 10 , 000 won.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2008년도 추계 공동 국제학술대회
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• pp.629-633
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• 2008

Recently, there has been great interest in the application of short-range wireless communication system. In this paper, the miniaturized FM transmitter with low power is developed, and laboratory tests have been carried out. The FM transmitter uses FM radio waves to send sound from any system (MP3, PMP, PDA, MP3 Phone et.) to any nearby radio or stereo system. The transmitter is designed with $2.6cm{\times}2.6cm{\times}2.6cm$ system size. The operating voltage is 3.7 V and used the built-in storage battery. The system can use continuously during 7 hour with once charging. The transmission frequency can select one of 88.1 MHz, 88.3 MHz, or 88.5 MHz in compliance with utility condition. The channel separation ability is 40 dB. The operating temperature is $-10{\sim}+85^{\circ}C$, which use in the industry environment. Consequently, this system sis used conveniently with short distance information transmitter system at the industry field.

• 설비공학논문집
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• 제26권10호
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• pp.467-473
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• 2014

Since the operating conditions of HVAC systems are different from those for which they are designed, on-going commissioning is required to optimize the energy consumed and the environment in the building. This study presents a methodology to analyze operational data and its applications. A predicted operation model is to be produced through a statistical data analysis using multiple regressions in SPSS. In this model, the dependent variable is the pre-cooling time, and the independent variables include the power output of the supply air inverter during pre-cooling, the supply air set temperature during pre-cooling, the indoor temperature-indoor set temperature just before pre-cooling, supply heat capacity, and the lowest outdoor air temperature during non-cooling/non-heating hours. The correlation coefficient R2 of the multiple regression model between the pre-cooling hour and the internal/external factors is of 0.612, and this could be used to provide information related to energy conservation and operating guidance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.471-474
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• 2000

A flat type microgas sensor was fabricated on the p-type silicon wafer with low stress S $i_3$ $N_4$, whose thickness is 2${\mu}{\textrm}{m}$ using MEMS technology and its characteristics were investigated. W $O_3$thin film as a sensing material for detection of N $O_2$gas was deposited using a tungsten target by sputtering method, followed by thermal oxidation at several temperatures (40$0^{\circ}C$~$600^{\circ}C$) for one hour. N $O_2$gas sensitivities were investigated for the W $O_3$thin films with different annealing temperatures. The highest sensitivity when operating at 20$0^{\circ}C$ was obtained for the samples annealed at $600^{\circ}C$. As the results of XRD analysis, the annealed samples had polycrystalline phase mixed with triclinic and orthorhombic structures. The sample exhibit higher sensitivity when the system has less triclinic structure. The sensitivities, $R_{gas}$ $R_{air}$ operating at 20$0^{\circ}C$ to 5 ppm N $O_2$of the sample annealed at $600^{\circ}C$ were approximately 90. 90.

• 한국양식학회지
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• 제12권1호
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• pp.47-56
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• 1999

순환여과식 어류 양식 시설에서 호기성 미생물의 질산화 작용에 의하여 암모니아는 질산염으로 산화되어 축적되며 이를 제거하기 위하여 협기성 미생물을 이용한 탈질산화 과정을 많이 이용하고 있다. 이 과정에서 혐기성 미생물에 의한 탈질산화 효율은 외부 탄소원의 종류, 수리학적 체류시간(hydraulic retention time, HRT) 및 외부 탄소원 농도에 대한 수중 질산염의 농도비율 ($COD/NO_3^-N$, C;N)에 따라 달라진다. 따라서 우리 나라 순환여과식 양식장에서 일반적으로 이용되고 있는 선라이트 골판을 여과 재료로 한 침지식 여과조를 탈질 여과조로 이용하여 적정 유기 탄소원 제거 조건을 구명하기 위해 질산염의 농도를 순환여과식 양어장의 일반적인 농도인 $20.0mg/\ell$로 고정하고 외부 탄소원으로 메탄올과 글루코스를 사용하여 HRT와 C:N 비율 변화에 따른 적정 제거 조건을 알아보았다. 외부 탄소원의 종류에 따른 질산성질소의 제거 효율은 어떤 실험 조건에서도 메탄올이 글루코스보다 높게 나왔으며 HRT의 경우 글루코스와 메탄올 어느 쪽도 HRT 4시간 보다 8시간에서 효율이 좋았다. (P<0.05). HRT 8시간에서 C:N의 비율 3,4,5,6 중에서 5까지는 효율이 증가하여 글루코스의 경우 최대 제거 효율은 76.5%였고 일간 제거속도는 $223.5 g/m^2/day$였다. 그러나 외부 탄소원으로 메탄올을 사용할 경우 C:N 비율이 6으로 증가하면 효율이 감소되었다. HRT가 4시간일 경우 일간제거속도는 C:N 비율 5의 조건에서 메탄올이 $355.6g/m^2/day$로 가장 높았으나 배출수에 포함된 유기물 농도가 $40.9 mg/\ell$로 양어 용수에는 부적당하였다. 적정 제거 조건으로 생각되어지는 HRT 8시간, C:N 비율 5, 유기탄소원으로 메탄올을 사용하여 유입수의 질산성질소 농도를 $40.9 mg/\ell$ 로 높일 때 일간 제거속도는 질산성질소 농도가 20.6 mg/\ell$일 때 보다 2.2배가 증가하였다. 또한 배출수의 질산성질소 농도도 $5.6 mg/\ell$로 나타나 질산성질소의 일간제거속도는 높아졌으나 C:N 비율 5를 맞추기 위한 메탄올의 농도 증가로 인하여 배출수의 메탄올 농도가 $71.3 mg/\ell$로 증가하여 양식 dydt로는 부적당하였다. 따라서 선라이트 골판을 이용한 침지식 탈질조의 최적 운전 조건은 HRT 8시간, C:N 비율 5및 외부 탄소원으로 메탄올을 이용하는 것이 가장 좋은 결과를 나타내었다. 유입수의 질선성질소 농도가 증가하면서 질산성질소의 일간제거속도도 함께 증가하였고 이에 따라 수중 pH도 8.0에서 8.8까지 점차적으로 증가하는 결과를 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.104-104
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• 2015

Due to the demand of the cold neutron flux in the neutron science and beam utilization technology, the cold neutron source (CNS) has been constructed and operating in the nuclear research reactor all over the world. The majority of the heat load removal scheme in the CNS is two-phase thermosiphon using the liquid hydrogen as a moderator. The CNS moderates thermal neutrons through a cryogenic moderator, liquid hydrogen, into cold neutrons with the generation of the nuclear heat load. The liquid hydrogen in a moderator cell is evaporated for the removal of the generated heat load from the neutron moderation and flows upward into a heat exchanger, where the hydrogen gas is liquefied by the cryogenic helium gas supplied from a helium refrigeration system. The liquefied hydrogen flows down to the moderator cell. To keep the required liquid hydrogen stable in the moderator cell, the CNS consists of an in-pool assembly (IPA) connected with the hydrogen system to handle the required hydrogen gas, the vacuum system to create the thermal insulation, and the helium refrigeration system to provide the cooling capacity. If one of systems is running out of order, the operating research reactor shall be tripped because the integrity of the CNS-IPA is not secured under the full power operation of the reactor. To prevent unscheduled reactor shutdown during a long time because the research reactor has been operating with the multi-purposes, the introduction of the standby cooling system (STS) can be a solution. In this presentation, the design considerations are considered how to design the STS satisfied with the following objectives: (a) to keep the moderator cell less than 350 K during the full power operation of the reactor under loss of the vacuum, loss of the cooling power, loss of common electrical power, or loss of instrument air cases; (b) to circulate smoothly helium gas in the STS circulation loop; (c) to re-start-up the reactor within 1 hour after its trip to avoid the Xenon build-up because more than certain concentration of Xenon makes that the reactor cannot start-up again; (d) to minimize the possibility of the hydrogen-oxygen reaction in the hydrogen boundary.

• 대한기계학회논문집A
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• 제34권12호
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• pp.1909-1915
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• 2010

고온의 연소가스에서 운전되는 국내 가스터빈 부품들은 매일 기동정지를 반복함으로써 열사이클에 의해 재료특성에 변화가 발생한다. 최근 많은 가스터빈 고온부품들이 단결정 초내열 합금으로 제작되어 지지만 재료열화 예측을 통한 부품 교체와 정비에 대한 기준이 없어서 대부분 제작사에 의존하고 있는 실정이다. 본 연구에서는 향후 수명평가와 손상분석의 기초자료로 활용하기 위해 실제 운전된 가스터빈 1 단 블레이드의 열화상태를 조사하였다. 사용한 블레이드는 25,000 및 52,000 의 등가운전시간(EOH : Equivalent Operating Hour)을 가졌으며, 재질은 단결정 초내열합금인 CMSX-4 이다. 사용된 블레이드에서 직접 시험편을 채취하여 기계적특성 시험 및 미세조직을 관찰하였다.