• 로봇학회논문지
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• 제15권3호
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• pp.269-276
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• 2020

As we become an aging society, the number of elderly patients continues to increase. Pressure sores that can easily occur in patients with trauma cause serious socio-economic problems. In general, prevention of bedsores through predicting the patient's posture is being developed. Developed method usually use artificial intelligence techniques to estimate the patient's posture by measured pressure images in the mattress. In this method, it has a problem the reduction of estimation accuracy when posture of patient is changed. Therefore, it is necessary to use the filter of pressure images in the position transition of patient. In this paper, we propose an algorithm to predict the patient's posture, and an algorithm to reduce the ambiguity that can occur in the patient's posture transition section. By obtaining stable data through this algorithm, learning/prediction stability of the neural network can be expected, and prediction performance is improved accordingly. Through experiments, the effectiveness of the algorithm was verified.

• 열처리공학회지
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• 제3권3호
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• pp.5-12
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• 1990

This study has been conducted to establish the carburizing characteristics of low carbon alloy steels with varying amount of Ni element gas-carburized for 2 hours at $930^{\circ}C$ in an atmosphere of 94% $N_2$-6% $C_3H_8$ gas mixture with some changes in gas pressure passing through the diffusion plate in the fluidized-bed furnace. The results obtained from the experiment are as follows : (1) Optical micrograph has shown that the carburized layer consists of retained austenite and plate martensite and that retained austenite increases as the pressure of gas mixture passing through the diffusion plate as well as Ni content increase. (2) Chemical analysis has shown that carbon potential increases and carburizability is also improved due to a less degree of fluidization as the pressures of gas mixtures passing through the diffusion plate increase, resulting in, however, a severe formation of soot, and the gas pressure is necessarily regulated. (3) It has been revealed that carbon concentration hardness values at a given distance measured from the surface within the carburized case. Increase with increasing the pressure of gas mixtures passing through the diffusion plate and decrease with increasing Ni content. (4) The effective case depth has been shown to almost linearly increase as the pressure of gas mixtures passing through the diffusion plate is increased and to decrease with increasing Ni content.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제29권4호
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• pp.29-35
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• 2023

Purpose: The 2015 Middle East Respiratory Syndrome (MERS) outbreak and the recent COVID-19 pandemic have highlighted the lack of negative pressure isolation rooms and the fragility of the healthcare system. The need for healthcare facility transformation for respiratory infectious diseases has become more prominent due to COVID-19, and the purpose of this study is to provide a foundation for the rapid, economical, and safe construction of negative pressure isolation wards. Methods: This study analyzes the current status of hospitals that have been converted to negative pressure isolation rooms, and provides architectural plans and examples to provide a reference for bedroom change. Research data of this study have been obtained by analyzing the drawings of negative pressure isolation wards of nationally designated inpatient treatment beds and urgent isolation beds. In addition, the relevant literature of urgent isolation beds has been analyzed to derive bedroom change type. Result: In this study, a total of 21 isolation bed conversion methods have been presented. Implications: In order to change efficiently from a general ward to an isolation ward, it is necessary to consider the actual hospital's infectious disease transmission patterns and facility conditions.

• 설비공학논문집
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• 제14권4호
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• pp.315-323
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• 2002

The commercial viability of heat exchanger is mainly dependent on their long-term fouling characteristics because the fouling increases the pressure loss and degrades the thermal performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The present work showed that the drag force coefficients of particles in the internal flow were higher than those in the external flow, in addition, the solid particle periodically hitting the tube wall broke the thermal boundary layer, and increased the rate of heat transfer. Particularly when the flow velocity was low, the effect was more pronounced.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.39-45
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• 2004

The commercial viability of heat exchanger is mainly dependent on their long-term fouling characteristics because the fouling increases the pressure loss and degrades the thermal Performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The Present work showed that the flow velocity range for Possible collision between the tube wall and the particles was higher with heavier density solid particles. in audition. the solid particle periodically hitting the tube wall broke the thermal boundary laver. and increased the rate of heat transfer.

• 한국약용작물학회지
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• 제26권6호
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• pp.490-497
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• 2018

Background: The growth process of ginseng seedlings is very important in producing good quality ginseng. This study was carried out to investigate the effects of different microclimates on the growth characteristics of ginseng seedlings in a multi-layer bed facility. Methods and Results: Ginseng seedlings were cultivated in a three-layer bed facility. The air temperatures on the first and second floors were similar, while that on the third floor was about $1-4^{\circ}C$ higher than that on the other floors. The vapor pressure deficit (VPD) was higher inside than on the outside of the facility, and that on third floor was the highest in the multi-layer bed system. The photosynthetic rate, chlorophyll fluorescence, and growth characteristics of ginseng seedlings did not significantly differ among the three floors. The yield of ginseng seedlings was the highest at $721g/1.62m^2$ on the first floor. Conclusions: It was found that microclimate plays an important role in growing ginseng seedlings in multi-layer bed facilities, and therefore proper environmental control is important. In addition, producing ginseng seedlings using multi-layer bed facilities is a technology that is expected to provide a way to overcome climate change and stabilize ginseng production.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.337-345
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• 2012

To check effects of operating variables on reaction characteristics of WGS catalyst for SEWGS process, water gas shift reaction tests were carried out in a pressurized fluidized bed reactor using commercial WGS catalyst and sand(as a substitute for $CO_2$ absorbent) as bed materials. Simulated syngas(mixed with $N_2$) was used as a reactant gas. Operating temperature was $210^{\circ}C$ and operating pressure was 20 bar. WGS catalyst content, steam/CO ratio, gas velocity, and syngas concentration were considered as experimental variables. CO conversion increased as the catalyst content and steam/CO ratio increased. CO conversion at fluidized bed condition was higher than that of fixed bed condition. However, CO conversion were maintained almost same value within the fluidized bed condition. CO conversion decreased as the syngas concentration increased. The optimum operation condition was confirmed and long time water gas shift reaction test up to 24 hours at the optimum operating conditions was carried out.

• 청정기술
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• 제19권2호
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• pp.165-172
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• 2013

본 연구에서는 고정층 반응기(높이 15 cm, 내경 0.5 cm)에서 K-계열 건식 흡수제($K_2CO_3/Al_2O_3$, 한국전력공사 전력연구원)를 이용하여 반응압력 변화에 따른 염화수소 흡수 실험을 수행하였다. 반응온도는 가스화 직후, 필터를 거쳐서 주입되는 것을 가정하여 $400^{\circ}C$로 설정하였으며, 반응기체 농도는 750 ppm HCl ($N_2$ balance)으로 설정하였다. 반응압력은 1, 5, 10, 15, 20 bar로 증가시켰다. 압력이 증가할수록 K-계열 흡수제의 흡수 성능이 증가하였다. 흡수제를 구성하고 있는 주요 물질인 $K_2CO_3$가 HCl 가스와 반응하여 KCl 결정을 형성하였으며, 강한 결합에너지로 인하여 흡수제의 재생이 실질적으로 불가능하였다. 이에 대한 광학적, 물리적, 화학적 특성을 SEM, EDX, BET, TGA, XRD를 이용하여 분석하였다. $400^{\circ}C$, 20 bar 조건(가스화 이후 탈할로겐 공정의 온도 및 압력조건)에서 $K_2CO_3$ 흡수제는 Ca 계열 및 Mg 계열의 흡수제에 비해 높은 HCl 흡수능 및 HCl/$N_2$ 분리 거동을 보였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.284-287
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• 2005

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 decomposition reaction was carried out at the temperature range of $850-925^{\circ}C$, methane gas velocity of $1.0U_{mf}\;3.0U_{mf}$ 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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.761-764
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• 2009

The thermocatalytic decomposition of methane is an environmentally attractive approach to $CO_2$-free production of hydrogen. The fluidized bed was proposed for the continuous withdraw of product carbon from the reactor. The usage of carbon black was reported as stable catalyst for decomposition of methane. Therfore, carbon black (DCC-N330) is used as catalyst. A fluidized bed reactor made of quartz with 0.055 m I.D. and 1.0 m in height was selected for the thermo-catalytic decomposition. The porpane-containg methnae decomposition reaction was operated at the temperature range of 850-900 $^{\circ}C$ methane gas velocity of 1.0 $U_{mf}$ and the operating pressure of 1.0 atm. In this work, propane was added as reactant to make methane conversion higher. Therefore we compared with methane conversion and pre-experiment methane conversion that using only methane as reactant. The carbon black, after experiment, was measured in particle size and surface area and analyzed surface of the carbon black by TEM.