• 한국식품저장유통학회지
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• 제4권3호
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• pp.237-243
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• 1997

Numerous variables affect product cooling rate of pressure cooling system for fruits and vegetables. These include carton vent area, initial and desired final product temperature, flow rate and temperature of the cooling air, product size, shape and thermal properties and product configuration(whether in bulk or packed in shipping cartons). This study was carried out to determine the influence of each of these variables as they affect cooling time. The opening ratio and number of the vent hole were recomended as 4∼10% and 2∼4ea., respectively, for a minimum alt flow resistance and for a uniform air flow pattern. In the cooling experiment for tomatoes and mandarins, optimum air flow rate was 0.04 m3/min.kg in terms of energy saving. The cooling air temperature should be about 2$^{\circ}C$ less than the desired final product temperature for reducing cooling time.

• Journal of Biosystems Engineering
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• 제20권4호
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• pp.333-342
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• 1995

The resistance to air flow through fruits and vegetables in bulk was an important consideration in the design of the pressure cooling system. The amount of resistance to air flow through produce in bulk normally depended upon air flow rate, stacking depth, porosity, stacking patterns and shape and site of product. But, there was not enough information relating the effects of those factors on air flow resistance. The objectives of this study were to investigate the effect of stacking depth, stacking patterns, porosity and airflow rate on airflow resistance and to develop a statistical model to predict static pressure drop across the produce bed as a function of air flow rate, stacking depth, bed porosity, and product size. Mandarins and tomatoes were used in the experiment. The airflow rate were in the range of 0.1~1.0 ㎥/s.$m^2$, the porosity were in the range of 0.25~0.45, the depth were in the range of 0.3~0.9m and the equivalent diameters were 5.3cm and 6.3cm for mandarins, and 6.5cm and 8.5cm for tomatoes. Three methods of stacking arrangement were used i.e. cubic, square staggered, and staggered stacking arrangement. The results were summarized as follows. 1. The pressure drops across produce bed increased in proportion to stacking depth and superficial air velocity and decreased in proportion to porosity. 2. The increasing rates of pressure drop according to stacking patterns with the increase of superficial air velocity were different one another. The staggered stacking arrangement produced the highest increasing rate and the cubic stacking arrangement produced the lowest increasing rate. But it could be assumed that the stacking patterns had not influenced greatly on pressure drops if it was of equal porosity. 3. The statistical models to predict the pressure drop across produce bed as a function of superficial air velocity, stacking depth, porosity, and product diameter were developed from these experiments.

• Journal of Biosystems Engineering
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• 제20권4호
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• pp.343-350
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• 1995

In order to design efficient and effective pressure cooling system for fruits and vegetables, a numerical model for temperature prediction of fruits was developed. This model was extended to study the various factors affecting product cooling time, such as product depth, approach air temperature, entering air velocity and initial product temperature. Also, selection of these factors were examined with respect to the efficiency of the pressure cooling system, the overall precooling cost and the final quality of the product. When designing a pressure cooling system for a particular product, the range of the factors must be selected carefully according to the thermal and physiological properties.

• 설비공학논문집
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• 제23권4호
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• pp.281-286
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• 2011

The objective of this study is to optimize the four-bed six-step pressure swing adsorption(PSA) process for high purity $CH_4$ recovery from the biogas. The effects of P/F(purge to feed) ratio and cycle time on the process performance were evaluated. The cyclic steady-states of PSA process were reached after 12 cycles. The purity and recovery rate of product gas, pressure and temperature changes were constant as the cycle repeated. It was shown that the P/F ratio gave significant effect on the product recovery rate by increasing the amount of purge gas in purge and regeneration step. The optimal P/F ratio was found to be 0.08. As the cycle time increased, the product purity decreased by increasing the feed gas flow rate. It was found that the optimal operating conditions were P/F ratio of 0.08 and total cycle time of 1,440 seconds with the purity of 97%.

• 대한임상검사과학회지
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• 제50권2호
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• pp.136-143
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• 2018

심근부담률은 심근산소소비량을 간접적으로 측정하는 지표로 심박수와 수축기 혈압의 곱으로 나타내며, 심근이 받는 부담을 나타낸다. 본 연구는 한국성인을 대상으로 트레드밀 운동부하 검사시 대사증후군에 따른 심근부담률의 적정 수준을 제시함으로써 대사증후군 유병률을 낮추기 위한 심근부담률의 목표치를 설정하여 그 기준을 제시하고자 하였다. 대사증후군 진단은 National Cholesterol Education Program (NCEP)의 Adult Treatment Panel (ATP) III에서 제시한 5가지 진단기준 중 3개 이상 충족하는 경우 대사증후군 진단군(MetS, N=25), 1~2개의 기준에 해당하는 경우를 대사증후군 전단계군(Pre-MetS, N=106), 5개의 진단기준에 해당하지 않는 경우는 대사증후군 위험요인이 없는군(Non-MetS, N=65)으로 분류하였다. 운동부하검사는 Bruce 프로토콜에 따라 시행하였다. 심근부담률은(심박수${\times}$수축기 혈압)${\div}1,000$으로 구하였다. 본 연구결과 대사증후군 진단군에서 도달한 일량이 낮음에도 불구하고 최대 수축기 혈압이 높은 것으로 나타났다. 또한 대사증후군에 따른 운동부하 검사시 심근부담률의 최적 임계점은 운동부하검사 1단계에서는 $12.56mmHg{\times}beats/min{\times}10^{-3}$, 운동부하검사 2단계는 $16.94mmHg{\times}beats/min{\times}10^{-3}$, 운동부하검사 3단계에서는 $21.11mmHg{\times}beats/min{\times}10^{-3}$로 나타났다.

• 청정기술
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• 제15권2호
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• pp.75-80
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• 2009

공기 중에서 산소를 분리하기 위하여 2탑 PSA 공정을 이용한 4단계 기본공정 공급기체의 유량과 세정기체의 유량이 생성물의 순도와 유량에 미치는 영향을 살펴보았다. 4단계 기본 공정에 생성물가압 단계를 도입하면 생성물의 순도와 유량을 증가시키고, 압력균등화단계를 도입한 경우에는 생성물의 유량이 크게 증가한다는 사실을 확인할 수 있었다. 현재 상용화되어 있는 의료용 산소 발생기 사양인 5 ${\ell}/min$ 유량에서 순도 90%의 산소를 얻기 위해 시제품을 제작하여 산소의 순도 및 유량에 관한 실험을 수행하였다.

• 한국가스학회지
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• 제10권3호
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• pp.60-64
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• 2006

카본블랙 제조공정에서 발생되는 부생가스의 폭발한계와 폭발특성을 연구하였다. 부생 가스의 75% 가량은 수분과 질소였으며 가연성 성분으로는 수소를 비롯한 메탄, 아세틸렌, 일산화탄소 등을 포함하고 있어 연료로 활용하고 있다. 부생 가스중의 가연성 가스 성분들에 의해 공정상에 폭발 및 연소의 위험이 있다. 실험결과 얻어진 폭발한계범위는 17.1%에서 70.7%였으며 르샤틀리에 법칙을 이용하여 예측한 값과는 상당한 차이가 있었다. 또한 폭발특성 실험 결과 폭발압력은 최대 $5.4kg/cm^2$이었고 평균 폭발압력 상승속도는 $39.2kg/cm^2/s$였다. 이러한 결과들은 부생 가스의 취급 및 이용에 따른 폭발이나 화재 사고시 공정과 시설 등에 치명적인 손상을 입힐 수 있으므로 가스폭발 방지 및 방호조치가 필요하다.

• International Journal of Internet, Broadcasting and Communication
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• 제13권3호
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• pp.130-136
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• 2021

The purpose of this study was to investigate the effect of the intensity of warm-up exercise on the physiological response and exercise performance during resistance exercise. For this purpose, 8 male college students with at least 1 year of experience in resistance movement were selected. The warm-up condition was set to NON condition (preparatory exercise not performed), 3 set condition, 6 set condition, and 9 set condition, and the intensity was different for each set. After warm-up, 75% 1RM of main exercise was performed, and blood pressure and heart rate were measured immediately after exercise to measure RPP. The number of repetitions and total work for each condition were measured as the number of repetitions and momentum during the main exercise. The measured data were analyzed by repeated measures two-way ANOVA. As a result, although there was no difference in Rate Pressure Product according to the warm-up conditions, the number of repetitions and total amount of exercise showed the highest in the 3-set condition. Therefore, it is thought that the number and intensity of warm-up exercises should be set appropriately during resistance exercise, and warm-up of 3 sets or more during resistance exercise is thought to decrease exercise performance.

• Biomolecules & Therapeutics
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• 제7권2호
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• pp.170-177
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• 1999

PEG-hemoglobin SB1 (SB1), which is a hemoglobin-based oxygen carrier, is intended to use as a safe blood substitute against brain ischemia and stroke. The general pharmacological profiles of SB1 were studied. The doses given were 0, 5, 10, 20 ml/kg and drugs were administered intravenously. The animals used for this study were mouse, rat and guinea pig. SB1 showed no effects on general behavior, motor coordination, spontaneous locomotor activity, hexobarbital sleeping time, anticonvulsant activity, analgesic activity, blood pressure and heart rate, left ventricular peak systolic pressure, left ventricular end diastolic pressure, left ventricular developing pressure, double product, heart rate, coronary flow rate, smooth muscle contraction using guinea pig ileum, gastrointestinal transport, gastric secretion, urinary volume and electrolyte excretion at all doses tested except the decrease of body temperature. These findings demonstrated that SB1 possesses no general pharmacological effects at all doses tested.

• International journal of advanced smart convergence
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• 제13권1호
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• pp.185-193
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• 2024

This study aimed to investigate the immediate physiological responses, including heart rate, blood pressure, and rate pressure product (RPP), following squat exercises performed at three water depths (ground, knee depth, waist depth) and two speed conditions (60bpm speed, Max speed). The participants consisted of 10 men in their 20s with over 6 months of resistance exercise experience. For the 60bpm speed squats, participants performed 30 repetitions in 1 minute at a rate of 2 seconds per repetition, while for Max speed squats, they performed at Max speed without a set limit on the number of repetitions for 1 minute. All experiments were conducted with a random assignment. The study results showed that immediately after the aquatic squat exercise, the average heart rate, blood pressure, and cardiac load were higher in the order of knee depth, ground level, and waist depth at both 60bpm speed and Max Speed. At 60bpm speed, the heart rate was higher in the order of ground level, knee depth, and waist depth. Overall, exercise in an aquatic environment was considered to impose relatively lower physical burden compared to land-based exercise. Therefore, it is suggested that depending on individual fitness levels and exercise goals, appropriately combining aquatic exercise, which imposes lower immediate physiological burden, and land-based exercise may lead to safer and more effective exercise methods.