• Korean Journal of Human Ecology
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• v.11 no.3
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• pp.273-285
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• 2002

Three materials for sport underwear were manufactured by order for study, and among them, suitable material in order to perform an experiment on the effect of wearing was adopted. The results are as follows: The result of wearing an experimental clothes for sports manufactured as a foundation-type underwear for sports showed that if the same compositional materials were applied, laminating material had higher rate than that of others in the amount of sweat. Concerning relative humidity in clothes and the amount of sweat absorbed in clothes among the two kinds of materials which were produced by laminate, material 2(nylon+modal) was statistically exerts higher influence on the amount of sweat. The humidity in clothes keeps the optimal condition of 59.8%, and breast part showed the highest relative humidity. The material 2(nylon+modal) showed the highest comfortableness, the sense of warmth, humidity and voluminousness, and the sense of pressure. Follow-up survey revealed that in case of material 2, higher amount of sweat than that of the group objects in its early phase, and the amount of sweat varies from individuals. The temperature in clothes of folded parts of experimental clothes and maximum surface temperature was equivalent to that of average skin. With the lapse of time, the weight decreased of 11.03% in maximum, and 3.12% in minimum. The amount of change in the girth was greater in part of body frame than that of limbs, and especially, navel and waist part showed high decrease, and upper breast, breast and the largest part of abdomen showed relatively low decrease. The above experiment revealed that materials for suitable to the underwear for sports for loss of weight by an exercise should be made of doubled-nylon and modal, along with the laminate processing, which heightens the amount of sweat. Thus, wearing an experimental wear gave satisfaction in the view of the beauty of appearance as it did not discharge flowing secretion to the outside at the time of exercise.

• Journal of the Korean Home Economics Association
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• v.11 no.4
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• pp.374-387
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• 1973

This work was carried out to investigate the changes of chemical and physical properties of frying oil, when it was used many times continuously without adding new oil. Four kinds of frying oil (soybean oil, rapeseed oil, shortening and crude lard) and slices of potato and Aji (kind of fish) were used in the experiment under the condition of home cooking. Obtained results were as in the followings. 1. Acid values and peroxide values of each frying oil were under the safety level (A. V = 1.5, Po. V = 50) except crude lard, when frying works were continuously repeated five times for 50 days. 2. Changes of saponification values of each frying oil showed a decreasing tendency except the crude lard. But in cases, stickiness or clothing of oil were not seen in frying even at the five times frying. 3. Changes of optical density of each frying oil showed a decreasing tendency in all cases, according to the times of frying, especially at the first time frying. 4. Maximum heights of the shamp of each frying oil and their shampholding activites when heated, were slowly increased according to the times of frying. 5. Without concerning the cooking condition (kinds of oil, cooking material and repeating times of frying) decrement of oil in once frying was almost exactly 20g per 150g. 6. Decrements of cooking material in all cases of frying showed almost constant values, potato to be 40% and Aji 20%. 7. Differences of smoke point between new and old oil (frying repeated 5 times) showed also almost constant values. Liquid oil (soybean oil and rapeseed oil) showed number (6-$10^{\circ}C$), on the contrally solid oil (shortening and crude lard) a high number (10-$25^{\circ}C$). 8. Results of public tastic for the frying products were almost good even in that of a low five times frying, but the products, of third time frying with crude lard were expressed as disagreeable.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.184-184
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• 2009

Lead-free Piezoelectric $[Li_{0.04}(Na_{0.44}K_{0.56})](Nb_{0.88}Ta_{0.1}Sb_{0.02})$ (abbreviated as NKNLTS) has been synthsized by conventional mixed oxide method traditional ceramics process without cold-isostatic pressing. Effect of $Bi_2O_3$ addition on NKNLTS ceramics was investigated. Piezoelectric properties of the ceramic were varied with the amount of $Bi_2O_3$ addition and showed the maximum Kp value at 0.4wt% $Bi_2O_3$ addition. The results show that the optimum poling condition for NKNLTS ceramics of 3.5kV/mm, poling temperature of $120^{\circ}C$ and poling time of 30min. At the sintering temperature of $1100^{\circ}C$ and the calcination temperature $800^{\circ}C$, the optimal values of density=$4.7g/cm^2$, Kp=0.44, $\varepsilon_r$=1309 were obtained. Consequently, lead free piezoelectric ceramics with the excellent piezoelectric could be fabricated using a conventional mixed oxide process and the optimal manuacturing condition of those was obtained.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.76-80
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• 2010

Oil hydraulic piston pumps are being extensively used around the world, because of their simple design, light weight, effective cost, etc. An oil hydraulic pump is likely to have the serious problems of high leakage, friction, and low energy efficiency after a long period of use. In an oil hydraulic piston pump, the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this study, the wear property of the SACM645 material with DLC coating used for a hydraulic piston pump was determined by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, five different types of specimens were prepared. The maximum tensile strengths of the QT and QT Nitration specimens had similar values of about 800 MPa, but the strains indicated a big difference. In a wear test, the wear characteristic of the DLC coating specimen was shown to be excellent. The QT, QT + IH, QT + Nitration, and matirx specimen showed similar wear characteristics. In the case of a dry condition without oil, the DLC coating specimen had good wear resistance, with no wear shown.

• Journal of the Korean Magnetics Society
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• v.22 no.6
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• pp.210-215
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• 2012

The absorption performance of a metal-backed single layered electromagnetic wave absorber is optimized at matching conditions of thickness and frequency indicating the maximum returns loss of incidence electromagnetic wave in the contour map. These matching conditions are obtained by applying the electromagnetic impedance to the transmission line theory, which depend on the complex permeability and complex permittivity of absorber material. The magnetic materials with high permeability can enhance the matching thickness condition to the wide frequency range based on the decrease of permeability with frequency and it can be used as a wideband electromagnetic wave absorber material. Therefore, the magnetic materials with higher saturation magnetization and lower permittivity than NiZn ferrite can be applied to the wideband electromagnetic wave absorber in order to satisfy the newly enforcing the electromagnetic compatibility regulation in the future.

• Water for future
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• v.6 no.2
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• pp.12-18
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• 1973

This paper describes the study and test for sand and gravel embankment in winter season and also contribute to the development of construction method for the practical purposes. In order to make possible sand and gravel embankment in winter season, at first, the following eriteria on work are given under the normal weather condition: 1) The maximum diameter of material shall not exceed 30cm and sand content which is the ratio of the weight of sand to gravel shall not exceed 60% 2) Spreading depth shall not exceed 60cm each layer of material shall be compacted by over 6 times passing by thell ton smooth drum type of uibratory roller and the relative density shall exceed 60% In addition to the above conditions, the following criteria are given as winter season condition. 3) Sand contsnt shall not exceed 25%, and water content shall not exceed 4% 4) Dwing construction, the air temperature should be $70^{\circ}C$ below zero at minimum and $3^{\circ}C$ below zero onthe average and all the construction work should he continued without intersuptions. With above criteria, it is come to a conclusion that the conclusion that the construction of sand and gravel embankment in winter season will be done satisfactorily without any difficulty. On the basis of these criteria an actual construction was practiced and it was proved that those criteria are applicable to actual embankment of materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.169-172
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• 2020

In this paper, the effect of hot carrier injection on an n-bulk fin field-effect transistor (FinFET) is analyzed. The hot carrier injection method is applied to determine the performance change after injection in two ways, channel hot electron (CHE) and drain avalanche hot carrier (DAHC), which have the greatest effect at room temperature. The optimum condition for CHE injection is V_G=V_D, and the optimal condition for DAHC injection can be indirectly confirmed by measuring the peak value of the substrate current. Deterioration by DAHC injection affects not only hot electrons formed by impact ionization, but also hot holes, which has a greater impact on reliability than CHE. Further, we test the amount of drain voltage that can be withstood, and extracted the lifetime of the device. Under CHE injection conditions, the drain voltage was able to maintain a lifetime of more than 10 years at a maximum of 1.25 V, while DAHC was able to achieve a lifetime exceeding 10 years at a 1.05-V drain voltage, which is 0.2 V lower than that of CHE injection conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.136-141
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• 2021

Heating cables, widely used in office buildings, factories, streets and railways, deteriorate in electrical insulation during operation. The insulation deterioration of heating cables leads to electric discharges that can cause electrical fires. With this background, this paper dealt with a condition monitoring technique for heating cables by the analysis of discharge signals to prevent electrical fires. Insulation deterioration was simulated using an arc generator specified in UL1699 under AC operation, and the characteristic and propagation of discharge signals were analyzed on a 100 meter-long heating cable. Discharge signals produced by insulation deterioration were detected as a voltage pulse because they are as small as a few mV and they are attenuated through propagation path. The frequency spectrum of discharge signals mainly existed in the range from 70 kHz to 110 kHz, and the maximum attenuation of the signal was 84.8% at 100 meters away from the discharge point. Based on the experimental results, a monitoring device, which is composed of a high pass filter with the cut-off frequency of 70 kHz, a comparator, a wave shaper and a microprocessor, was designed and fabricated. Also, an algorithm was designed to discriminate the discharge signal in the presence of noise, compared with the pulse repetition period and the number of pulse counts per 100ms. In the experiment, the result showed that the prototype monitoring device could detect and discriminate the discharge signals produced at every discharge point on a heating cable.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.166-178
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• 1991

Using FLAC, which is an explicit finite difference code written for analysis of problems in geotechnical engineering, a particular example 2 in the Korean Geothechnical Society News has been analysed. The elastoplasticity formulation in FLAC assumes an elastic, perfectly plastic solid in plane strain which conforms to a Mohr-Coulomb yield condition. During tunnel excavations by stages, stresses and diaplacements in region around the tunnel varies according to distance from the face of tunnel and installation of tunnel supports, and soon. In this analysis, the three dimensional support effect of the rock mass during the process of excavation is simulated by using the stress distribution method, and varying the material constants of shotcrete in each stage also considered. The maximum convergency is occured at the crown of the tunnel and estimated to be about 12mm.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.93-96
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• 2017

The structural, electrical and optical properties of Ti thin films fabricated by dual magnetron sputtering were investigated under various film thicknesses. The fabricated Ti thin films exhibited uniform surfaces, crystallinity, various grain sizes, and with various film thicknesses. Also, the crystallinity and grain size of the Ti thin films increased with the increase of film thickness. The electrical properties of Ti thin films improved with the increase of film thickness. The results showed that the performance of TCO-less DSSC critically depended on the film thickness of the Ti working electrodes, due to the conductivity of Ti thin film. However, the maximum conversion efficiency of TCO-less DSSC was exhibited at the condition of 100 nm thickness due to the surface scattering of photons caused by the variation of grain size.