• Journal of Korean Society of Transportation
• /
• v.34 no.2
• /
• pp.146-157
• /
• 2016

The objective of this study is to actualize a statistical model of the 3-detector simplification model, which was proposed to detect outbreak situations by Daganzo in 1997 and to verify the statistical appropriacy thereof. This study presents the calculation process of the 3-detector simplification model and realizes the process using a statistics program. Firstly, the model was applied using data on detector of the main highways on which there is no entrances or exits. Moreover, in order to statistically verify the 3-detector simplification model, accumulative traffics for 30 seconds period, which reflects the dynamic changes of traffics due to shock wave, were estimated for outbreak traffics and steady flow, and the error of acquired data was statistically compared with that of the actual accumulative traffics. As a result, the error ratio between steady and incident cumulative flows has reached its maximum after 2-3 hours from an accident. Moreover, the incident traffic flows by accidents and the stade flows are heterogeneous in terms of their dispersion and means.

• Geotechnical Engineering
• /
• v.3 no.1
• /
• pp.25-38
• /
• 1987

The prediction of driving stresses in piles is necessary for optimum selection of driving hammers, better design of precast piles, enact assessment of drivabilities and complete description of piling specifications. However, the existing pile-driving formulas based on the theory of Newtonian impact have some defects and shortcomings; the numerical method by the wave equation analysis using electronic computer usually Involves various uncertainties and limitations which can yield erroneous outcomes because it employs soil constants of which the nature is unknown as essential parameters and ignores the effect of residual stresses set up in the pile .after each hammer blow; and the electronic measuring technique needs extra time and expense. The method developed herein is presented for the purpose of giving field engineers a reliable and convenient analytical procedure for the prediction of driving stresses along the full length of pile using the most effetive parameters without resort to electronic computer. This method is based on the fundamental mechanics of stress waves in elastic rods and takes into account the effect of residual stresses induced by reversed friction in piles.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.7
• /
• pp.891-897
• /
• 2013

In this study, the compressive deformation behaviors of aluminum alloy under high strain rates were investigated by means of a SHPB test. An acoustic emission (AE) technique was also employed to monitor the signals detected from the deformation during the entire impact by using an AE sensor connected to the specimen with a waveguide in real time. AE signals were analyzed in terms of AE amplitude, AE energy and peak frequency. The impacted specimen surface and side area were observed after the test to identify the particular features in the AE signal corresponding to the specific types of damage mechanisms. As the strain increased, the AE amplitude and AE energy increased whereas the AE peak frequency decreased. It was elucidated that each AE signal was closely associated with the specific damage mechanism in the material.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.6
• /
• pp.99-109
• /
• 1999

In the case of domestic general waste landfills, cumulated leachate level is often formed in the landfill due to the waste of high moisture content and it becomes important to characterize the hydraulic properties of the disposed waste. Although many hydrologic studies have been peformed for leachate barriers and pheriperal subsurface environments, few studies have been done to investigate the hydraulic property of the disposed waste and cover soils and to analyse the leachate flow behavior within landfills. In this paper, the geotechnical properties of the waste and buried cover soils are identified through the field experiment including pumping and slug tests. The results of various tests show that the field density of the cover soils is somewhat higher than the maximum laboratory density of cover soils and the vertical flow of leachate and gas in the landfill is prevented by the buried cover soils. The hydraulic conductivities of field pumping test and slug tests are well matched and stayed in the range of hydraulic conductivities of well compacted wastes in the literature.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.4
• /
• pp.429-434
• /
• 2014

Purpose: To analyze thermal effect on mechanical properties of domestic commercial polymer-based eyewear frames. Methods: In this study, materials of cellulose acetate, polyamide, epoxy, and polyetherimide were exposed to high or low temperature and were mounted on universal test machine (TO-100-IC) for tensile strength test. Elastic behavior, Young's modulus, maximum displacement, and fatigue were tested with various temperature ($-25^{\circ}C$, $25^{\circ}C$, $60^{\circ}C$). Results: As a result, at room temperature, displacements of materials were changed with increasing impact load. At low temperature ($-25^{\circ}C$), maximum displacements of all specimens were decreased but young's modulus were increased. However, at high temperature, maximum displacements of all specimens were increased but young's modulus were decreased. Conclusions: Degree of displacements due to fatigue behavior was increased following direction of PEI, epoxy, polyamide, acetate. We concluded that commercial polymers used in eyewear frames physical properties were changed differently to exposed temperature.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2003.07a
• /
• pp.347-352
• /
• 2003

농산물 포장화물의 경우 농산물의 손상은 겉포장 상자의 파손에 의한 압상이 주요 원인이다. 따라서 농산물 상자의 경우 압축강도를 특히 중요시 여기고 있으며, 한국산업규격을 비롯해 각종 농산물 관련 규정에서는 압축강도에 의한 상자의 품질관리를 규정화 하고 있다. 골판지 상자의 압축강도는 원단인 골판지의 구성 원지들(라이너, 골심지)의 품질과 이들의 구성 형태 및 상자의 외형 치수 비율에 따라 결정되므로, 원지의 링크라쉬(ring crush), 원단의 수직압축강도(edgewise compression strength)를 통해 상자의 압출강도를 관리하는 것이 보통이다. 또한 골판지 상자는 제작 후 유통 과정을 거치면서, 여러 요인에 의해 압축강도가 현격하게 저하되는데, 이중 수분 흡습에 의한 강도저하와 장기 누적하중, 진동 및 충격 등의 피로로 인한 강도 저하가 가장 크다. 여러 산업 분야에서 골판지 상자의 견고성 문제는 물품의 내수 및 수출시 제품에 대한 신뢰성 확보와 기업의 이미지 제고와 직결되는 중요한 사항이다. 특히, 세계 각 국의 농산물 시장이 개방됨에 따라 우리나라 농산물의 수출도 확대될 전망이고 또한 마땅한 대체재가 개발되지 않는 한 골판지 상자의 이용은 날로 증가될 것으로 전망된다. 따라서 골판지 상자의 압축강도와 내구성 향상에 대한 다각적인 연구가 절실하다. (중략)

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.1
• /
• pp.91-99
• /
• 2006

Large steel industries have nonlinear loads including electric arc furnaces and harmonic field measurements have shown that harmonic content of a waveform varies with time. Since the large loads are supplied from the power system grid, it must be recognized that not only will the system of utility be impacted, but neighboring customer system could be impacted as well. In this paper time-varying harmonics are evaluated by international harmonic standards IEEE Std. 519 and IEC 61000-3-6 using a cumulative probablistic approach.

• 연구논문집
• /
• s.34
• /
• pp.79-85
• /
• 2004

There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving 'Knockdown stress' to hose assemblies just until before the hose assemblies get out of order.

• Korea Real Estate Review
• /
• v.28 no.1
• /
• pp.115-130
• /
• 2018

This study investigated the factors influencing the termination of the JooTeakYeonKeum contract according to its rate increase, and aimed to identify the differences in the factors affecting the cancellation of the contract according to the collateralized house price range. The results showed that the higher the cumulative increase rate of the mortgage housing price at the time of subscription is, the higher the monthly payment, the larger the gap between the monthly payment and the minimal living expenses for aging, the lower the net population moving rate in the previous month, and the lower the cumulative mortgage. Moreover, the JooTeakYeonKeum contract is terminated. The factors affecting the termination of the contract are different in each interval of the price range of the mortgage housing. To confirm this, a mortgage price range model was constructed and analyzed. The results showed that 60% of the elderly participants in the JooTeakYeonKeum program subscribed thereto with a below-average subsidized housing price. It was confirmed that the factors affecting the termination of the contract differ by price range. Lowering the risk of increasing the JooTeakYeonKeum termination rate will be a significant way of boosting the welfare of elderly people aged 65 and older, and of easing the impact of population aging.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.30 no.4 s.48
• /
• pp.471-477
• /
• 2004

Exposure to elevated temperatures, chemical (active oxigen), or physical stress (UV light) induces immediate physiological response, the expression of heat shock proteins in cells. Thus, cells with elevated Heat Shock Protein levels become more tolerant to stress conditions that are otherwise lethal. First, we studied on the new function of glucuronic acid (GA) as preventive material of skin aging. The application of the GA shows significant induction of Heat Shock Protein 70 kDa (HSP 70 kDa) in contrast to cells without it. GA at the concentration which can induce HSP 70 kDa, protects the cell death induced by second stress (heat shock and hydrogen peroxide) in NIH3T3 cells. Second, we studied on in vitro transdermal permeation characteristic of GA through the excised mouse skin. In this study, we compared the skin permeability of GA in water with O/W emulsion. As a result, skin permeation parameters of GA shows lag time 1.2 h, partition coefficient 0.114, permeation flult rate $0.83114 mg/cm^2/h.$ In case of lag time, O/W emulsion containing GA increase 2.48 h. Also, the total accumulation permeation content decreased in contrast to GA solution after 24 h. But it has long-term permeability of glucuronic acid. These results suggest that glucuronic acid could be a good cosmetic active ingredient.