• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.398-403
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• 2005

This study investigates the change of the temperature and mechanical properties of the braking disk for the railway vehicle. The average temperature is measured about $100^{\circ}C$ and the maximum temperature is measured over $200^{\circ}C$ by non-contact sensor from Seoul to Chun-an. In the $20^{\circ}C-300^{\circ}C$, the 0.2% offset yield strengths of the disk (GC25-30 material) are a little down to the reference value, but the linear relation of tensile test result is not find from the linear change of temperature. However, JIC values have the inverse proportion to the temperature, and the JIC value at $200^{\circ}C$ decrease 30.55% from the JIC. value of the room temperature. This result means that the crack length on the braking disk is rapidly increase at $200^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• 제18권2호
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• pp.36-48
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• 1990

This experiment was carried out to improve the quality of high absorbent polymer which has excellent absorptivity and water retention compared to pulp and absorption sheet, through absorption characteristics-absorptive power, water retention, absorption rate, gel strength, pH, particle size, and moisture content. - of six polymers, namely, anionic polyacrylamide, cationic polyacrylamide, polyacrylic, acid polyvinyle alcohol 500, and 1500, and a-cellulose. and to examine the possibility of substitution of amide groups for carboxyl group and/or hydroxyl group which were commercial high absorbent polymer by comparing the absorption characteristics of the polymers. Polyacrylamide has high absorptive power and water retention, but has low gel strength and poor absorption rate. The rest of polymers were similiar to ${\alpha}$-cellulose in every respect. Thus, polyacrylamides could be replaced with polyacrylic acid and polyvinyl alcohol which are presently a high absorbent polymers. In comparing the absorption characteristics and the absorptive power of the polymers-anionic polyacrylamide, cationic polyacrylamide, polyacrylic acid, polyvinyle alcohol. a-cellulose-the absorptive power was in inverse proportion to the gel strength and absorption rates, affected by the particle size and pH change.

• 대한방사선기술학회지:방사선기술과학
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• 제2권1호
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• pp.23-29
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• 1979

Roentgenographic film has to be handled with greatest care during removal from the packing, loading of the cassettes and loading of the hanger. In the case of prior to or after exposed film is handled with mechanical pressure in darkroom, the most common phenomena are desensitization or sensitization on roentgenographic film. In order to observe these defect occurring on, it, the author studied on change of the densities where the mechanical pressure reached to the roentgenographic film. 1. The optimal minimum and maximum densities in routine chest x-ray film are from 0.25 to 1.47 2. The dependence of the desensitization occurring on film upon the bent degree of film is in the portion to bent degree over $10^{\circ}$ 3. Appearances of the desensitization on film by the curved degree of film is inverse proportion to it's degree below intervals of 3cm. 4. The more unexposed film is bent with nail tip and is pressured with palm, the more desensitization it was appeared upon film size and pressure weight. 5. The most serious area of desensitization produced by many types of mechanical pressure is in the portion of lung apex and outside lung fields. 6. The tendency of desensitization due to mechanical pressure on unexposed film is more serious than sensitization on exposed film in the view of radiologic diagnosis.

• 한국연소학회지
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• 제10권1호
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• pp.20-26
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• 2005

In the present study, catalytic combustion of hydrogen-air premixture in a millimeter scale monolith coated with Pt catalyst was investigated. As the combustor size decreases, the heat loss increases in proportion with the inverse of the scale of combustion chamber and combustion efficiency decreases in a conventional type of combustor. Combustion reaction assisted by catalyst can reduce the heat loss by decreasing the reaction temperature at which catalytic conversion takes place. Another advantage of catalytic combustion is that ignition is not required. Platinum was coated by incipient wetness method on a millimeter scale monolith with cell size of $1{\times}1mm$. Using this monolith as the core of the reaction chamber, temperatures were recorded at various locations along the flow direction. Burnt gas was passed to a gas chromatography system to measure the hydrogen content after the reaction. The measurements were made at various volume flow rate of the fuel-air premixture. The gas chromatography results showed the reaction was complete at all the test conditions and the reacting species penetrated the laminar boundary layer at the honeycomb and made contact with the catalyst coated surface. At all the measuring locations, the record showed monotonous increase of temperature during the measurement duration. And the temperature profile showed that the peak temperature is reached at the point nearest to the gas inlet and decreasing temperature along the flow direction.

• 분석과학
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• 제13권3호
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• pp.269-276
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• 2000

역상액체크로마토그래피에서 7종의 벤조산의 머무름에 대해서 연구하였다. 벤조산의 불감시간 측정은 무기염이 적당하였다. 로그 용량인자(log k')와 Hildebrand의 용해인자(${\delta}$)는 직선관계를 가지며 머무름 메카니즘이 소용매성 효과에 영향을 받는다. 용질의 전이 엔탈피는 온도증가 그리고 이동상에서 유기변형제의 비와 반비례 관계를 가진다. 이동상에서 물의 부피분율과 log k'의 관계로부터 얻은 기울기인 S값은 양의 값을 가진다. 자유에너지 변화는 유기변형제의 부피분율의 증가와 비례한다. 소수성지표 ${\varphi}_0$은 컬럼의 온도와 반비례한다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권12호
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• pp.5035-5042
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• 2014

Background: Knowledge and individual perceptions about adverse effects of all forms of tobacco exert direct influence on the level of tobacco consumption in various socio-demographic groups. The objective of this study was to determine the nature, extent and demographic correlates of knowledge, attitudes and perceptions of use of tobacco among adults in low and middle income countries. Materials and Methods: The Global Adult Tobacco Survey, conducted in fourteen different countries from 2008-2010, was sourced for the data analyzed in this study. Descriptive statistical analyses were conducted to determine the prevalent knowledge and individual perceptions amongst adults about all forms of tobacco consumption. Results: There was relatively high awareness about the harmful effects of smoking tobacco with main awareness being about its relationship with lung cancer (>90% in most countries). In contrast, there was relatively low awareness about harmful effects of smokeless tobacco (< 90% in all countries except India and Bangladesh), and observed correlation of smoking tobacco with heart attack (40.6% in China, 65.1% in India) and stroke (28.2% in China, 50.5% in India). Conclusions: A large proportion of adults living in low and middle income countries possess adequate knowledge about smoking tobacco but have inadequate awareness as well as false perceptions about smokeless forms of tobacco. Popular beliefs of inverse relationships of tobacco consumption with knowledge, attitudes and perception of populations towards tobacco are challenged by the findings of this study.

• Applied Biological Chemistry
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• 제38권4호
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• pp.325-329
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• 1995

응고제 양, 두유 가열 온도, 성형 압력과 같은 두부 제조 공정에 따른 두부의 조직 강도를 파손강도와 초음파의 지연시간 측정을 이용하여 측정하였다. 응고제 양은 0.3%에서 두유 가열 온도는 $95^{\circ}C$에서 최대 파손강도를 나타내었고 성형압력은 압력이 증가할수록 파손강도가 증가하였으며 그에 상응하는 초음파의 잔존시간은 파손강도와 반비례하여 감소하는 경향을 나타내었다. 각 제조공정을 변수로 하여 중회귀 분석을 한 결과 초음파의 잔존시간으로 예측된 예측 파손강도와 실측정한 파손강도 값들 사이에는 유사함을 나타내어 초음파를 이용한 초음파 잔존시간의 변화는 식품조직의 변화에 따라 민감한 변화를 나타내므로 식품 제조 공정중 품질관리 측면에서 초음파의 사용이 기대되어진다.

• 한국농공학회논문집
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• 제56권1호
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• pp.21-30
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• 2014

The objective of this study is to find the electrical properties of Bottom ash from thermoelectric power plants in Korea. By using Parallel Plate Method, the electrical resistivity and dielectric constant were measured at the frequency from 20 Hz to 10 MHz. Also, unconfined strength test, XRF and sieve analysis were performed for finding the relationship between strength, physiochemical properties and electrical properties. In the result, the change of electrical resistivity and dielectric constant of bottom ash against frequency was similar to that of general soil. The proportion of fine grain in bottom ash had the positive correlation with dielectric constant and negative correlation with electrical resistivity. Chloride and sulfur trioxide were proportional to dielectric constant and the more bottom ash had chloride content, the lower electrical resistivity appeared in bottom ash. Unconfined strength of bottom ashes had a range from 200 kPa to 780 kPa and strength was inverse proportional to electrical resistivity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.84-86
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• 2005

The digital systems such as PLC or DCS have been applied to non-safety systems of nuclear power plants because of many difficulties in using analog systems. Nowadays, digital systems have been applied to safety systems of the plants such as reactor protection system. One of the main advantages of digital systems is applicability of automatic testing methods to the systems. The protection system requires high-reliability and high-availability because it shall minimize the propagation of abnormal or accident conditions of nuclear power plants. The calculation of reliability and availability of systems depends on the maintenance period of the system. In general, the maintenance period of the protection system is one-month in case of the manual test. However, the cycle of test can be shortened in several hours by using automatic periodic testing. The reliability and availability of the system is better when test period is shortened because the reliability and availability is inverse proportion to the test period. In this research, we developed the automatic periodic testing method for KNICS Reactor Protection System, which can test the system automatically without an operator or a tester. The automatic testing contained all functions of reaction protection systems from analog-to-digital conversion function of the bistable Processor to the coincident trip function of the coincident processor. By applying the automatic periodic testing to reaction system, the maintenance cost can be cut down and the reliability can be increased.

• 대한치과교정학회지
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• 제21권1호
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• pp.31-51
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• 1991

This study was designed to survey the stress distributions and deflections which were derived from MEAW by the computer-aided three dimensional finite element analysis of teeth and surrounding bone composed of 2839 solid elements and 4621 nodes. MEAW model was also made using the 90 beam elements and the results were expressed by quantitative and visible ways. The findings of this study were as follows. 1 In case of vertical load on the MEAW there were extrusions of anterior teeth and upright effects of the posterior teeth. 2. Without applying the vertical elastics on the MEAW there were intrusions of anterior teeth, but relatively mild force was transmitted to the posterior teeth area. Torque forces were observed on the incisors and molars, and canine was intruded without torque. 3. The magnitudes of forces were different by the amounts of tip back bends of MEAW. 4. The displacements were in inverse proportion to the cross section areas of the wires according to the experiment using the 5 different size arch wires. 5. The difference of deflections between the MEAW and plain arch wire was not so big as the theoretical one but the deflections of MEAW were much more than the plain arch wire in every X, Y, Z direction.