• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.428-439
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• 1992

Drying process in a fixed bed red pepper dryer was modeled and simulated. Drying efficiency describing the effectiveness of energy usage in red pepper drying was defined as a ratio of energy used for moisture evaporation to total energy consumption, and expressed in combination of measurable temperature variables. The efficiency was compared with real evaporative efficiency and tested in the simulated and experimental drying. An overall drying efficiency was derived, and analyzed for various control variables consisting of drying temperature, air recycle ratio and air flow rate. Optimal operation conditions of drying was then searched by Box's complex method by using it as an objective function. Carotenoids retention was simulated and put as a constraint of product quality in the optimization. The optimization results gave that two staged drying operation could improve the ding efficiency compared with single staged drying. As a technique for further energy saving automatic termination of drying appeared feasible by monitoring an exit air temperature from dryer.

• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.342-349
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• 1982

Filefish muscle in the form of thin plate $(5{\times}10{\times}0.4\;cm)$ was dried in a forced air dryer at $47.5^{\circ}C$ to study the relation between dehydration mechanism and water activity. The dryer was designed in such a way that the temperature, relative humidity and velocity of air could be controlled. The whole dehydration process of the filefish muscle was divided into two different drying rate periods, constant and falling rate period. During the constant drying rate period, the drying rate was proportional to the square root of air velocity under the conditions of constant temperature and relative humidity of air. The falling rate period was further divided into two different falling drying rate periods, first and second falling rate period. The first falling rate period was an unsaturated surface drying period caused by partial unsaturation of the drying surface with capillary condensed free water diffused from the internal part of the filefish muscle. At this stage he drying rate was mainly dependent on the relative humidity at constant air temperature, and case-hardening phenomenon started at the end of this stage. The moisture content and the water activity at which the second falling rate period started were not constant, because the drying rate of the first falling rate period was strongly dependent on the air humidity. The second falling rate period was again divided into two drying rate periods, former and latter period. The drying rates of both of these periods were independent on the external air humidity. During the former period of the second falling rate period, the dehydration was proceeded by diffusion and vaporization of capillary condensed free water in filefish muscle. The diffusion coefficient of water was $2.89{\times}10^{-10}m^2/sec\;at\;47.5^{\circ}C$. At this stage, the case-herdening continued until the water activity reduced to 0.7. The latter period of the second falling rate period started at the water activity of 0.45. The dedydration was proceeded by diffusion and vaporization of bound water, which adsorbed in multimolecular layers, through the hardened drying surface. The number of molecular layers was 4, and the diffusion coefficient of water during this stage was $4.38{\times}10^{-11}m^2/sec\;at\;47.5^{\circ}C$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.251-254
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• 2007

본 연구는 $SF_6$를 대체하기 위한 건조공기(Dry-Air)의 특성을 연구할 목적으로 교류 및 직류고전압 인가 시 압력(P)변화 및 갭 길이의 변화에 따른 절연파괴특성을 연구하였다. 본 연구를 통해 챔버 내의 P가 증가할수록 절연파괴특성은 증가하는 것을 확인했다. 그리고 불평등전계 보다 평등전계에서 절연파괴특성이 더 증가하고 전극간거리(d)가 증가할수록 절연파괴특성이 증가하는 것을 확인했다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.247-249
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• 2007

본 연구는 $SF_6$를 대체하기 위한 건조공기(Dry-Air)의 특성을 연구할 목적으로 교류고전압 인가 시 압력(P)변화 및 갭 길이의 변화에 따른 절연파괴특성을 연구하였다. 본 연구를 통해 챔버 내의 P가 증가할수록 절연파괴 특성은 증가하는 것을 확인했다. 그리고 불평등전계 보다 평등전계에서 절연파괴특성이 더 증가하고 전극간거리(d)가 증가할수록 절연파괴특성이 증가하는 것을 확인했다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1597-1598
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• 2011

현재 $SF_6$ 가스를 사용하는 각국 정부 및 환경단체, 전기, 화학 그리고 타 산업분야에서 $SF_6$ 가스의 환경영향에 관심을 표명하고 있으며, 그 중에서도 전력산업분야는 $SF_6$의 가스 대체 물질을 찾는데 많은 연구를 하고 있다. 이에 건조공기, $N_2$ 가스 및 혼합가스($N_2:O_2$)에 대하여 많은 연구로 $SF_6$를 사용하는 전력설비를 친환경절연재인 건조공기로 대체하여 배전급에 운용되고 있다. 따라서 본 논문에서는 현재 배전급에 친환경절연재로 사용되고 있는 Dry-Air에 대하여$SF_6$와의 연면 방전 특성 비교하여 고체절연물의 절연성 평가를 하였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.127-132
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• 1999

우리나라의 도시폐기물 소각로는 화격자 위에 폐기물을 공급하고 화격자 밑에서 공기를 공급하는 스토커식 소각로를 대부분 채택하고 있다. 이러한 스토커 소각로 연소실내에서는 매우 복잡한 연소현상이 발생하는데, 연소실로 투입된 쓰레기는 먼저 건조부에서 수분의 건조가 일어나고, 화격자의 구동에 의해 쓰레기가 혼합 및 이송되면서 열분해, 가스화, 가연성분의 탈휘발화 및 연소, 일부 고정탄소의 표면연소 등의 반응이 일어난다. 그리고 1,2차 연소실에서는 휘발분 및 비산된 고체의 연소가 일어나는데, 이때 대류 및 복사열전달 등의 복잡한 현상을 수반하는 유동장이 형성된다. 더욱이 불균질한 특성을 갖는 쓰레기층 내에서의 복잡한 현상으로 인하여 발생하는 경계조건 설정의 불확실성으로 연소실내의 연소 현상을 전산해석하는 데에는 상당한 어려움이 있다.(중략)

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1480-1481
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• 2007

본 연구는 SF6를 대체하기 위한 건조공기(Dry-Air)의 특성을 연구할 목적으로 교류전압 인가 시 압력(P)변화 및 갭길이의 변화에 따른 절연파괴특성을 연구하였다. 본 연구를 통해 챔버 내의 P가 증가 할수록 절연파괴특성은 증가하는 것을 확인했다. 그리고 불평등전계 보다 평등전계에서 절연파괴특성이 더 증가하고 전극간거리(d)가 증가 할수록 절연파괴특성이 증가하는 것을 확인했다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.765-770
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• 2008

Ji, Syok-young wrote a book named Sinhaksinseol(新學新說) in 1891, one of the first hygiene books in Korea. There were the conditions of modern housing like lighting, ventilation and dry and fresh air of a housing site in the contents of the book. Because the book was written when the modern hygiene theory had just been accepted, traditional concept of 'Yangseng(養生),' but it dealt the main environmental conditions of hygienic housing at first, which makes it the leader of modern housing discourses through the newspapers, magazines, academic journals or textbooks from 1890s mid to 1910.

• Korean Journal of Food Science and Technology
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• v.21 no.5
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• pp.655-661
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• 1989

Optimal drying conditions consisting of air temperature and relative humidity were searched by the simulation-optimization technique for minimizing quality changes in red pepper drying. Optimized drying conditions were analysed in the viewpoint of quality change kinetics and effects of control variables on the state variables. Optimal drying conditions were nearly same in both cases for carotenoid maximization and browning minimization. In two staged optimized drying, relative humidity took a lower search limit of about 10%, and air temperature in the first stage was near the lower limit of $50^{\circ}C$ and in second stage increased to a higher temperature varying with total drying time and stage changing time. Response surface analysis of time invariable drying confirmed the location of the optimal point lying on the vertex of lower limit humidity and a lowest drying temperature which ensures to attain target moisture of 0.2g water/g dry solid. Two stage drying can attain the higher objective function of quality by 3-5% than time invariable drying for shorter total drying times.

• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.5-14
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• 2023

The dry unit weight of the soil can be obtained by measuring the weight of the oven dried soil. According to the Korean Industrial Standards (KS F), oven dried soil at 110±5℃ continuously increases in weight when exposed to air. However, there is no regulation on the weight measurement time of oven dried soil, making it difficult to accurately measure the dry weight. In this study, a method to easily determine the dry weight was presented through the analysis of the weight singularity that appears during weight measurement. The weight singularity represents the smallest value among the measured weights, and is the weight at which the effect of moisture absorption in the air of the sample is minimized. In the course of the experiment, a container was selected using a statistical analysis method, and a photograph of the soil samples were presented using an optical microscope. In addition, the temperature of the weight singularity was measured using a non-contact infrared thermometer. As a result of analyzing the weight singularity of six types of soil, including Jumunjin sand, Naeseong stream sand, Yecheon weathered granite soil, Jeju sand, Sabkha sand, and Ulleung sand, the weight singularity of oven dried sample appeared between 8 and 27 seconds after weight measurement, and the temperature ranged from 103.4 to 108.13℃. The weight decrease rate of the singularity was 0.0066 to 0.0085% depending on the soil samples.