• 한국식품과학회지
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• 제16권1호
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• pp.23-28
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• 1984

멸치를 마쇄하여 자가소화시킬 경우 무염상태에서 20시간까지는 $50^{\circ}C$, pH 4라 최적조건이었고, 식염을 20% 첨가하였을 때는 $50^{\circ}C$, pH 6에서 가수분해가 가장 잘행해졌다. 한편 식염을 첨가하여 8 일동안 가수분해시킬 경우 최적조건이 $40^{\circ}C$, pH 6으로 변화하는 것으로 밝혀졌다. 상기한 최적조건에서 20시간동안 자가소화 시켰을 때 무염상태에서는 총질소중 60.5%가 TCA-가용성 질소를 가수분해되었으나 식염을 20% 첨가하였을 때는 49.8%로 낮아졌다. 그리고 가염상태에서 8 일간 가수분해 시킨 결과 총질소중 83.1%가 TCA-가용성질소로 분해되었고 계속하여 실온에서 52일간 숙성시킨 결과 총질소중 89.6%가 분해되었다.

• 한국분무공학회지
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• 제14권4호
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• pp.147-152
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• 2009

Since a liquid-phase LPG injection system allows accurate control of fuel injection and increase in volumetric efficiency, it has advantages in achieving higher engine power and lower emissions compared to the mixer type LPG supplying system. However, this system also leads to an unexpected event called icing phenomenon which occurs when moisture in the air near the injector freezes and becomes frost around the nozzle hole due to extraction of heat from surrounding caused by instant fuel vaporization. As a result, it becomes difficult to control air/fuel ratio in engine operation, inducing exacerbation of engine performance and HC emission. One effort to mitigate icing phenomenon is to attach anti-icing injection tip in the end of nozzle. Therefore, in this study, the effect of engine operation parameters as well as surrounding conditions on icing phenomenon was investigated in a bench test rig with commercially-used anti-icing injection tips. The test results show that considerable ice was deposited on the surface near the nozzle hole of the anti-icing tip in low rpm and low load operating conditions in ambient air condition. This is because acceleration of detachment of deposited ice from the tip surface was induced in high load, high rpm conditions, resulting in decrease in frost accumulation. The results of the bench testing also demonstrate that little or no ice was formed at surrounding temperature below a freezing point since the absolute amount of moisture contained in the intake air is too small in such a low temperature.

• 농업과학연구
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• 제20권1호
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• pp.9-17
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• 1993

'후지' 사과의 저장 및 유통 과정에서의 상품성 향상을 위한 몇가지 수확 후 처리기술을 검토한 결과 다음과 같은 결과를 얻었다. Polyethylene film 포장은 저장 중의 수분손실 방지에 따른 감량억제에 탁월한 효과를 보여 주었으나 저장기간이 걸어짐에 따라 PE 대내의 ethylene 축적으로 인한 과실의 노화가 심하였다. Polyethylene 포장과 ethylene scrubber를 함께 포장한 경우 저장 12주까지 선도유지에 효과적이었으나 장기저장에서는 ethylene scrubber의 효과가 저하되어 선도유지에 대한 효과가 감소되었다. 피막제 중 Prolong 처리는 감량 방지에 대한 효과가 인정되지 않았으나 수용성 wax 처리는 효과적이었다. 그러나 wax 처리는 일부 과실에서 조직의 괴사를 수반하는 장해를 유발하였으나 장해를 받지 않은 과실은 저장 21주까지 매우 신선한 상태를 유지하였다.

• 전기전자학회논문지
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• 제24권1호
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• pp.59-66
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• 2020

최근 휴대용 통신기기와 스마트 디스플레이의 결합은 휴대가 용이하고 이동을 하면서 모든 작업을 할 수 있다. 이에 본 논문에서는 휴대용 통신기기에서 저가격의 높은 투명전극을 찾기 위해 여러 가지 ITO(Indium Tin Oxide) 박막에 대해 연구하였다. ITO 박막은 DC 마그네트론 스펏터를 사용하였으며 1 분위기압을 1mTorr 증가 간격으로, 2 바이어스 전압은 10V 간격으로 변화시켜 측정하였다. 두께와 굴절율은 일립소미터를 사용하였으며 막의 단면과 표면의 형상은 주사전자현미경을 사용하여 조사하였다. 분석 결과를 통해 바이어스 전압이 300V 이상일 경우에 명확한 증착이 나타났으며 추가로 전압이 증가함에 따라 전체적으로 증착률이 증가하였다. 330V 조건에서 증착률이 가장 높았으며 뚜렷한 결정립이 관찰되었다.

• 한국환경보건학회지
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• 제35권1호
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• pp.1-10
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• 2009

This study assessed the relationships between levels of $PM_{10}$ and hospitalization rates for asthma among children from 2003 to 2005 at four major cities in Korea. In addition, we estimated the reduced number of asthma hospitalization associated with an ambient $PM_{10}$ improvement to the acceptable levels as recommended by the World Health Organization (WHO). The Generalized Additive Model (GAM) was used to estimate the relative risks (RR) of asthma hospitalization associated with changes in $PM_{10}$ The RRs of children's asthma hospitalization for every $10{\mu}g/m^3$ increment in $PM_{10}$ were 1.009(95% CI = 1.004-1.014) in Seoul, 1.013(95% CI = 1.006-1.021) in Incheon, 1.009(95% CI = 1.002-1.016) in Busan, and 1.021(95% CI = 1.005-1.037) in Ulsan. We assessed $PM_{10}$ related health benefits from implementing the WHO's guidelines (24-hour average $50{\mu}g/m^3$) using the U.S. Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program. The estimated benefits were 439(95% CI = 216-666) reduced asthma hospitalization in Seoul, 720(95% CI = 304-1,151) in Incheon, 260(95% CI = 66-459) in Busan, and 126(95% CI = 30-228) in Ulsan. It was concluded that improving $PM_{10}$ condition to the WHO guideline would make a significant contribution to the reduction in asthma hospitalization among children. Therefore, public health measures are still needed to improve air quality in Korea.

• 농업과학연구
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• 제38권4호
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• pp.747-752
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• 2011

Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

• 한국의류산업학회지
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• 제1권1호
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• pp.43-49
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• 1999

This study conducted 4 different kinds of underwear materials, which were A (Cotton 100%), B (Wool 100%), C (Cotton/Wool, 50/50%) and D (Acrylic/Cotton, 50/50%) and were done in a climate chamber under cold ambient $10{\pm}1^{\circ}C$, $40{\pm}5%RH$ by 6 male subjects who were in good health. Physiological parameters such as rectal and local skin temperature(forehead, forearm, hand, trunk, thigh, leg, foot, back and chest), heart rate, body weight loss, clothing microclimate, blood lactic acid concentration, and wearing sensation were measured. Started with a 15-min rest period, 15-min of exercise 1 (the condition of 4.5 mile/hr walking speed equivalent to with 8.5 Kcal energy consumption on the treadmill) period, 15-min rest period, exercise 2 (after 3minutes warming-up at 3.0. 3.7, 4.5. 5.2. 6.0, 6.7 mile/hr) until exhaustion period, and final 15-min of recovery period were performed. The results were as follows: The lowest mean skin temperature was acrylic/cotton in order of wool > cotton/wool > cotton > acrylic/cotton (F=13. 79. p<0.00l). Most of all skin temperature by parts of body had turned out in sequence of temperature wool > cotton/wool > acrylic/cotton > cotton. Fore arm part showed highest temperature about $32.43^{\circ}C$ on wool and had a tendency approximately $1.8^{\circ}C$ higher than cotton which had the lowest temperature, and had the biggest difference among garments in terms of skin temperature. The back temperature within clothing showed about $2^{\circ}C$ higher than the chest temperature within clothing. but the back humidity within clothing showed about 4~12% higher than the chest humidity within clothing. Body weight loss by each garment was this sequence; cotton > acrylic/cotton > wool > cotton/wool.

• 해양환경안전학회지
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• 제21권5호
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• pp.577-582
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• 2015

본 논문은 육해상의 운송장치에 축냉시스템을 적용시키기 위한 기초 연구이다. 또한, 축냉재의 고액상변화에 대한 수치해석을 수행한 연구이다. 수치해석법으로는 유한차분법(Finite-Difference Method)을 이용하였으며, 1차원 비정상의 상태를 가정하여 계산하였다. 또한 용기는 직사각형의 구형용기로 가정하여 대칭의 조건을 이용하였다. 축냉을 목적으로 사용하는 열매체는 염화칼슘 수용액($CaCl_2$) 30wt%의 물성치를 사용하여 계산을 수행하였다. 계산에 영향을 미치는 요소로는 냉동고의 냉기 온도 및 냉기 유속이 있으며, 축냉재를 싸고 있는 용기는 플라스틱으로 가정하였다. 본 수치해석에서 경계층의 두께는 냉기의 속도 증가와 함께 얇게 되고 축열시간도 짧아지는 것을 확인할 수 있었다. 그리고 냉기의 유속이 빨라질수록 열전달이 촉진되어 축냉용기 전면부에서의 온도가 낮아짐을 알았다. 축냉용기의 후면부에서는 경계층이 두꺼워져 열전달이 전면부에 비해 작아짐을 알았다.

• Smart Structures and Systems
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• 제25권1호
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• pp.111-122
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• 2020

Researchers up to date have introduced several Structural Health Monitoring (SHM) techniques with varying advantages and drawbacks for each. Satellite positioning systems (GPS, GLONASS and GALILEO) based techniques proved to be promising, especially for high natural period structures. Particularly, the GPS has proved sufficient performance and reasonable accuracy in tracking real time dynamic displacements of flexible structures independent of atmospheric conditions, temperature variations and visibility of the monitored object. Tall structures are particularly sensitive to oscillations produced by different sources of dynamic actions; such as typhoons. Wind forces induce in the structure both longitudinal and perpendicular displacements with respect to the wind direction, resulting in torsional effects, which are usually more complex to be detected. To efficiently track the horizontal rotations of the in-plane sections of such flexible structures, two main issues have to be considered: a suitable sensor topology (i.e., location, installation, and combination of sensors), and the methodology used to process the data recorded by sensors. This paper reports the contributions of the measurements recorded from dual frequency GPS receivers and uni-axial accelerometers in a full-scale experimental campaign. The Canton tower in Guangzhou-China is the case study of this research, which is instrumented with a long-term structural health monitoring system deploying both accelerometers and GPS receivers. The elaboration of combining the obtained rather long records provided by these two types of sensors in detecting the torsional behavior of the tower under ambient vibration condition and during strong wind events is discussed in this paper. Results confirmed the reliability of GPS receivers in obtaining the dynamic characteristics of the system, and its ability to capture the torsional response of the tower when used alone or when they are combined with accelerometers integrated data.

• Smart Structures and Systems
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• 제26권3호
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• pp.391-401
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• 2020

The present article reports the feasibility of the electrical energy generation from ambient low-frequency vibration using a piezoelectric material mounted on a bimorph cantilever beam actuator. A corresponding higher-order analytical model is developed using MATLAB in conjunction with finite element method under low-frequency with both damped and undamped conditions. An alternate model is also developed to check the material and dimensional viability of both piezoelectric materials (mainly focussed to PVDF and PZT) and the base material. Also, Genetic Algorithm is implemented to find the optimum dimensions which can produce the higher values of voltage at low-frequency frequencies (≤ 100 Hz). The delamination constraints are employed to avoid inter-laminar stresses and to increase the fracture toughness. The delamination has been done using a Teflon sheet sandwiched in between base plates and the piezo material is stuck to the base plate using adhesives. The analytical model is tested for both homogenous and isotropic material characteristics of the base material and extended to investigate the effect of the different geometrical parameters (base plate dimensions, piezo layer dimensions and placement, delamination thickness and placement, excitation frequency) on the model responses of the bimorph cantilever beam. It has been observed that when the base material characteristics are homogenous, the efficiency of the model remains higher when compared to the condition when it is of isotropic material. The necessary convergence behaviour of the current numerical model has been established and checked for the accuracy by comparing with available published results. Finally, using the results obtained from the model, a prototype is fabricated for the experimental validation via a suitable circuit considering Glass fibre and Aluminium as the bimorph material.