• 대한원격탐사학회지
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• 제32권6호
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• pp.603-616
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• 2016

본 연구에서는 기상청 현업 국지기상모델(Local Data Assimilation and Prediction System, LDAPS)과 전산유체역학(Computational Fluid Dynamics, CFD) 모델을 접합하여, 서울 종로구 송월동에 위치한 지동기상관측소(서울 ASOS) 주변 지역의 기상 환경을 분석하였다. 토지 피복별 차등 가열이 도시 지역의 대기 흐름과 기온에 미치는 영향을 분석하기 위하여, 시간 변화에 따른 토지 피복별 지표면 온도와 그림자 영역에 대한 지표면 온도 감소 효과를 고려하였다. LDAPS 모델은 상세한 건물, 지형, 지표면 가열 효과를 고려하지 못하기 때문에, 풍속을 과대모의 하고 기온을 과소 모의하였다. 건물과 지형의 마찰 효과와 태양 복사에 의한 지표면 가열을 고려할 수 있는 LDAPS-CFD 접합 모델은 서울 ASOS 지점의 관측 풍속과 유사한 풍속을 모의하였고, 관측 기온을 잘 재현하였다. 주로 동풍이 부는 오전 시간대에는 LDAPS-CFD 접합 모델 또한 기온을 과소모의 하였는데, 이는 서울 ASOS 지점의 풍상측(동쪽)에 위치한 경희궁 주변 지역에 주로 수목이 분포하고 있고, 표면 온도가 상대적으로 낮기 때문인 것으로 판단된다. 그러나, 주로 남동풍 계열의 바람이 부는 오후 시간대에는 풍상측에 위치한 건물의 표면 가열의 효과로 인해 서울 ASOS 지점의 관측 기온을 상대적으로 잘 모의하였다.

• Journal of Dairy Science and Biotechnology
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• 제34권4호
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• pp.271-278
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• 2016

The main purpose of milk heat-treatment is to improve milk safety for consumer by destroying foodborne pathogens. Secondly, heat-treatment of milk is to increase maintaining milk quality by inactivating spoilage microorganisms and enzymes. Pasteurization is defined by the International Dairy Federation (IDF, 1986) as a process applied with the aim of avoiding public health hazards arising from pathogens associated with milk, by heat treatment which is consistent with minimal chemical, physical and organoleptic changes in the product. Milk pasteurization were adjusted to $63{\sim}65^{\circ}C$ for 30 minutes (Low temperature long time, LTLT) or $72{\sim}75^{\circ}C$ for 15 seconds (High temperature short time, HTST) to inactivate the pathogens such as Mycobacterium bovis, the organism responsible for tuberculosis. Ultra-high temperature processing (UHT) sterilizes food by heating it above $135^{\circ}C$ ($275^{\circ}F$) - the temperature required to destroy the all microorganisms and spores in milk - for few seconds. The first LTLT system (batch pasteurization) was introduced in Germany in 1895 and in the USA in 1907. Then, HTST continuous processes were developed between 1920 and 1927. UHT milk was first developed in the 1960s and became generally available for consumption in the 1970s. At present, UHT is most commonly used in milk production.

• 열처리공학회지
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• 제37권4호
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• pp.182-187
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• 2024

To improve and control the mechanical properties of low alloy steel, the influence of quenching and tempering process conditions was investigated. In the case of quenching heat treatment, a comparison was made between the conventional method of heating to the austenite region followed by single quenching and a method involving double quenching, followed by high-temperature tempering. It was observed that specimens subjected to double quenching exhibited significantly finer tempered microstructures compared to those subjected to conventional quenching, resulting in noticeably higher hardness. Additionally, a study was conducted to investigate the variation in hardness with changes in tempering temperature and time after the same conventional quenching treatment. As expected, an increase in tempering temperature or time led to a decrease in hardness, and the correlation between hardness and the Hollomon-Jeffe Parameter was confirmed. It was also observed that during high-temperature tempering, the size of carbides significantly increased.

• 대한기계학회논문집
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• 제8권6호
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• pp.553-563
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• 1984

본 연구에서는 선정한 난방모델에 대하여 열회로망을 만들어 각 구성성분에 대하여 에너지평형식을 세워 시뮬레이션 모델을 구하고 여기에 경계조건과 초기조건을 대입하여 수치해석으로 푼 결과를 실측치와 비교하였다. 또한 축열벽의 열용량변화, 통기구의 개폐, 통기구에 자동온도조절 홴(fan)의 설치, 야간단열의 설치 및 온실크기 의 변화 등이 온방온도에 미치는 영향을 규명하였다.

• 대한설비공학회지:설비저널
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• 제16권4호
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• pp.415-420
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• 1987

The combustion kinetics of the imported bituminous coal was studied in the interme-diated heating rate. The activation energy and the frequency factor were obtained by experi-ment of the coal weight loss depending on the combustion time with Ih. furnace. The experi-ments were performed in the heating rates of $1,5,10^{\circ}C/sec\;or\;20^{\circ}C/sec\;at\;the\;600-900^{\circ}C$ maximum temperature, The values of the activation energy(E) which were calculated from the experimental data existed in the range from 3000cal/g-mol to 15000cal/g-mol, and those of the frequency $factor(1nk_O)$ were in the range from 4.5cm/sec to 11.5cm/sec.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.947-953
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• 2012

본 연구에서는 폐타이어 열분해 잔류물(char)을 이용하여 활성탄을 제조하기 위한 연구를 수행하였다. 활성탄 제조는 고정층 석영관 반응기에서 수증기를 이용한 물리적 활성화 방법을 사용하였으며, 주요한 실험 변수는 활성화 온도, 활성화 시간, 승온속도 및 활성화제의 주입량 등이다. 활성탄 제조 후 세공분포를 분석한 결과, 활성화 온도 $850^{\circ}C$, 승온속도 $5^{\circ}C$/min, 활성화 시간 3 hr의 조건에서 제조한 활성탄이 미세세공(micropore), 중간세공(mesopore) 및 거대세공(macropore)이 가장 많이 발달함을 알 수 있었다. 본 연구결과, 폐타이어 열분해 잔류물을 이용한 활성탄 제조의 최적 조건은 활성화 온도 $850^{\circ}C$, 활성화 시간 3 hr, 승온속도 $5^{\circ}C$/min, 활성화제 공급량 3 g $H_2O/char-g{\cdot}hr$ 등으로 조사되었다. 이 조건에서 제조한 활성탄의 BET 비표면적은 $517.6m^2/g$, 총 세공부피 $0.648cm^3/g$으로 나타나 활성탄으로서의 사용 가능성을 확인할 수 있었다.

• Food Science and Biotechnology
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• 제16권3호
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• pp.421-425
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• 2007

The inhibitory effect of onion extract on polyphenol oxidase (PPO) and browning of peach juice was investigated. Various reducing agents such as L-ascorbic acid, L-cysteine, dithiothreitol, glutathione, and sodium pyrosulfite strongly inhibited polyphenol oxidase extracted from peach. The enzyme was also inhibited by addition of water extract of onion. Regardless of substrates used, the addition of heated onion extract exhibited stronger inhibitory effect on peach polyphenol oxidase activity than that of the fresh one. The inhibitory effect of onion extract was dependent on heating temperature and time. The onion extract inhibited the peach polyphenol oxidase non-competitively. The heating of onion extract in the presence of glucose, glycine stimulated the inhibitory effect of the onion extract, which suggests non-enzymatic browning products produced during heating might be responsible for the stronger inhibitory action of the heated onion extract. The retardation of peach juice browning by onion extract seems to be caused by inhibition of peach PPO.

• 한국식품조리과학회지
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• 제31권3호
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• pp.360-369
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• 2015

The objective of this study was to develop remedies to improve sanitary quality of school meals. To analyze the usage of potentially hazardous foods, menus from 180 school foodservice establishments were collected through school websites. Statistical analyses were conducted using the SPSS package program (ver. 20.0). The results of this study are as follows: analysis of the foodservice production process revealed that the following were employed: heating process (70.5%), non-heating process (16.3%), and after-heating process (13.2%). In addition, the cooking methods used for side dishes were: stir-frying (22.1%), saengchae (21.3%), sukchae (15.2%), jorim (12.4%), deep-frying (10.2%), and grilling (9.5%). Overall, 64 menu items known to pose potential microbiological hazards were offered a total of 2,671 times. The usage frequency was high for bibimbap, pork-bulgogi, cucumber-saenchae, seasoned bean sprouts namul, seasoned spinach-namul, and korean cabbage-geotjeori. In conclusion, in order to increase the sanitary quality of school meals, menus or foods that contain microbiological hazards should prepared very carefully with respect to time and temperature management during food production. Also, school foodservice employees must possess proper food safety knowledge and techniques for applying the HACCP system to prevent foodborne illness.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.75-81
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• 2014

Recently, the use of renewable energy has been attracted due to the interest in energy-saving and the reduction of CO2 emission. In order to reduce the energy consumption of the cooling and the heating in the field of the architectural engineering, heat pump systems using renewable energy have been developed and used in various applications. In many researches, integrated heat pump systems are suggested which use solar and geothermal heat as the heat source for cooling and heating. However, it is still difficult to predict the performance of the systems, because the characteristic of heat exchange in each system is complicated and various. In this system, the performance prediction simulation of the heat pump was developed using a dynamic simulation model. This paper describes the summary of the suggested systems and the result of the simulation. The average temperature of the heat source, heating loads and COP were calculated with the cases of different local conditions, different system composition and different operation time by TRNSYS 17.

• 한국재료학회지
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• 제17권2호
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• pp.91-95
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• 2007

Electromigration characteristics of Sn-3.5Ag flip chip solder bump were analyzed using flip chip packages which consisted of Si chip substrate and electroplated Cu under bump metallurgy. Electromigration test temperatures and current densities peformed were $140{\sim}175^{\circ}C\;and\;6{\sim}9{\times}10^4A/cm^2$ respectively. Mean time to failure of solder bump decreased as the temperature and current density increased. The activation energy and current density exponent were found to be 1.63 eV and 4.6, respectively. The activation energy and current density exponent have very high value because of high Joule heating. Evolution of Cu-Sn intermetallic compound was also investigated with respect to current density conditions.