• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.425-430
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• 2018

The battery system of an electric vehicle suffers from the problem the battery output and the service life decrease at low temperature. A Positive Temperature Coefficient(PTC) heater is used for maintaining room temperature but is heavy due to a complicated insulation structure. The larger the weight is, the lower the fuel economy of the electric vehicle is. On the other hand a induction heater have a simple insulation structure, which is effective in weight reduction and has a rapid temperature rise. The induction heater consists of an LC resonance circuit. The larger the capacitance is, the higher the price and weight is. Therefore, the inductance should be increased to reduce the capacitance. Also, the main heat source of the induction heater is coreloss. So, it is important to optimize inductance and coreloss in terms of electromagnetic field design. In this paper, the inductance and the coreloss according to the change of the induction heater structure were optimized through the Taguchi method and Finite Element Method(FEM) simulation.

• Korean Journal of Poultry Science
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• v.40 no.1
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• pp.49-55
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• 2013

The objective of this study was to compare the principle components and internal quality of eggs by age of laying hens and weight standard. The eggs (2,140 in total) used were from Hy-Line Brown reared from 18 to 63 weeks of ages and all were higher than appearance grade B by animal grading standard of Korea. Eggs were investigated their principle components, internal quality index, and their relationship. The weights of whole egg, shell, yolk, and albumen were increased while albumen height and Haugh unit were decreased by age of laying hens. When the composition of egg was investigated after sorting by ages, the ratio of egg yolk increased while that of albumen decreased. Egg shell composition was not shown significant difference by age. Age of laying hens had positive correlation with the weights of whole egg, shell, yolk, and albumen while albumen height and Haugh unit showed negative correlation. Also, the albumen height and Haugh unit were decreased by increase of weight of whole egg or principle components of egg.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.109-112
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• 2014

A porous ceramic which has fine porosity and small specific gravity is made with Cenosphere and Ball Clay under condition of $1,250^{\circ}C$ in calcination temperature and 30 minutes of calcination time. The average size of porous ceramic was about $2.5{\times}10^{-5}$ m and pores are well developed. The void-fraction of porous ceramic was 67.1% under the input of Cenosphere and Ball clay with the weight ratio of 100 to 5. However, as weight ratio of Ball Clay increased to 20, 40, 100, the void fraction decreased to 58.4, 56.7, 47% respectively. When the weight ratio of Cenosphere and Ball Clay was 100 to 100, the apparent density of porous ceramic was $1.04g/cm^3$. which is twice the density when the weight ratio of Ball Clay was 5. On the other hand, absorption rate decreased by at least 100%. In condition of weight ratio of Cenosphere and Ball Clay was 100 to 100, compressive strength of porous ceramic was 30 (MPa), improve by about 76% or more when the weight ratio of Ball Clay was 5.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.100-107
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• 1984

농축산 배설물을 호기성 환기처리하여 토양에 환원이용을 목적으로 컴포스트(Compost)화 할 때에 공극률(Pore space)에 미치는 물리적인 자 성설의 상화관계를 공명하고져 실험을 수행하였다. 본 연구는 여러가지 수준의 압축력에 따른 첨가 재료의 공극률 변화 과정 측정하고 이와 동시에 서로 다른 5종류의 재료별 입자 크기에 대하여 영수률, 용적 중량, 용적 밀도 및 입자 대소가 공극률에 미치는 영향을 조사분석 하였으며 그 결과는 아래와 같다. 1. 세립자 재료의 용적 밀도는 세립자보다 더욱 크게 나타났다. 2. 염수률과 용적 중량이 증가하면 용적밀도는 커지나 공극률은 감소하였다. 3. 공극률은 영수률과 용적 중량보다 첨가재료의 입자크기와 대소분포에 더욱 커다란 영향을 받고 있었다. 4. 영수률이 55~65%이고, 용적중량이 0.25~0.38g/cm2이며 입자크기가 1.5~5cm인 범위내의 효율적인 콤포스트화에 있어서 공극률은 65~80%의 범위를 형성하고 있음을 알 수 있다.

• Korean Journal of Agricultural Science
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• v.15 no.2
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• pp.143-152
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• 1988

This study was conducted to obtain basic data which affected engine performance of the power tiller being widely used in the rural area. Among the various factors affected engine performance, only flywheel weight was considered as the major factor in this study. Fuel consumption ratio, motoring loss, torque, vibration and mechanical efficiency of the engine tested were measured and analyzed on the four levels of flywheel weight (32.2, 29.7, 26.4, 24.2 kg). The results obtained were as follows: 1. The maximum output of 6 and 7.5 kW engine was 7.43 kW and 7.85 kW respectively. When flywheel weight was reduced from 32.2 kg to 24.2 kg, output power of the engine was increased 0.27 kW in 6 kW engine and increased 0.39 kW in 7.5 kW engine. 2. The fuel consumption ratio was decreased from 300.8 to 296.8 g/kW-hr in 6 kW engine and decreased from 313.6 to 312.8 g/kW-hr in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 3. The mechanical efficiencies of the engine was increased from 76.1 to 76.8% in 6 kW engine and increased from 76.7 to 77.0% in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 4. When the flywheel weight was reduced from 32.2 kg to 24.2 kg, a tendency of a little decrease of vibration at X- and Z-axis in 6 kW engine and of a little increase of vibration at Y-axis in 6 kW engine and all directions in 7.5 kW engine was observed. 5. Motoring losses was decreased from 2.33 to l.76 kW in 6 kW engine and decreased from 2.46 to 1.84 kW in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. From the above results and the flywheel weight calculated theoretically, it was recommendable that the flywheel weight should be reduced about 7 kg in 6 kW engine and about 10 kg in 7.5 kW engine, respectively.

• Korean journal of food and cookery science
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• v.7 no.1
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• pp.61-66
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• 1991

In the present study, an attempt was made to determine the rutin contents in buckwheat noodles according to blending ratio and boiling time. The rutin contents in buckwheat flour was 17.30mg/100g. The rutin contents in raw buckwheat noodles decreased in proportional to the blending ratio of buckwheat flour from 15.34 to 4.78mg/100g. The rutin contents of buckwheat noodles decreased linearly with increasing boiling time.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.53-60
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• 2012

The main object of this paper is to investigate the effects of high temperatures on the physical and mechanical properties of natural sand concrete(NSC) and crushed sand concrete(CSC). Test samples were exposed to high temperature ranging from $200^{\circ}C$ to $800^{\circ}C$. After exposure, various tests were conducted. Color image analysis and weight losses were determined and compressive strength test and splitting tensile strength test were conducted. The results indicated that weight losses increased as exposure temperature increased with comparable decreasing rate. The results also showed that compressive strength and splitting tensile strength and modulus of elasticity decreased as exposure temperature increased. The results also showed that residual compressive strength of NSC decreased more drastically than that of CSC at $200^{\circ}C$ and $400^{\circ}C$. Residual splitting tensile strength of NSC decreased more than that of CSC at $200^{\circ}C$, while NSC and CSC showed comparable residual strength ratio at $800^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.30-37
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• 2005

This study aimed at offering basic data to develop a new use of sawdust and rice husk. Research investigated the variation of density, weight loss and dimensional decreasing rate by the percentage of resin impregnation and carbonization temperature of ceramics, which were formed by the percentage of resin impregnation of 40~80% and carbonization of $600{\sim}1200^{\circ}C$ with board impregnated with phenolic resin made from sawdust and rice husk. The results of this study were as follows:1) As the percentage of resin impregnation increased, the thickness shrinkage and weight loss were decreased; on the other hand, density and modulus of rupture increased. Meanwhile, the carbonization temperature at $1200^{\circ}C$ showed the highest values, as the density was $0.81g/cm^3$ and the bending strength was $77.9kgf/cm^2$ in the percentage of resin impregnation at 70%. 2) As the carbonization temperature grew higher the linear shrinkage, thickness shrinkage and weight loss increased while the density increased until the carbonization temperature of $1000^{\circ}C$; but then decreased slightly at $1200^{\circ}C$.

• Food Science and Preservation
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• v.10 no.1
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• pp.6-10
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• 2003

The objective of this study was to investigate the effect of browning inhibitor and vacuum packaging on minimally processed sweet pumpkin. The browning inhibitor were lo/e of ascorbic acid, citric acid, NaCl, MgCl$_2$and their combination. For the minimal processing, sweet pumpkin was sliced and strip-cut followed by dipping in the solution of browning inhibitor. Effective browning inhibitors fer slice sweet pumpkin were ascorbic acid, NaCl and MgC1$_2$, and those fer thin strip were combination and ascorbic acid. The hardness of minimally processed sweet-pumpkin repeated increasing and decreasing and decreased in the final of storage. However the change pattern of hardness was different according to cutting method. Magnesium chloride treatment was generally high grade on sensory characteristics. Sweet pumpkin treated with citric acid was distinguished on carbon dioxide generation and oxygen exhaustion.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.706-713
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• 2022

The study is to observe the time trend variation in the blood lead concentration of Korean teenage groups and to examine the changes in the daily lead intake from intake amount(g) by food groups as an influencing factor. A total of 1,540 subjects are participants in the Korea National Health and Nutrition Examination Survey (KNHANES) in 2011, 2012, 2014, 2016, and 2017. The blood lead concentrations were 1.25㎍/100ml in 2011 survey, 1.16㎍/100ml in 2012, 1.17㎍/100ml in 2013, 1.05㎍/100ml in 2016, and 0.84㎍/100ml in 2017. The time trend decrease in food intake amount appeared mainly in the plant food groups such as grains, potatoes and starch, pulses, mushrooms, vegetables, and fruits. And the milk and dairy products of the animal food group also showed a decreased trend. The decrease in the intake amount of these food groups can be an influencing factor in the decrease in lead concentration in the blood.