• Design & Manufacturing
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• 제13권4호
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• pp.17-22
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• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• 한국정밀공학회지
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• 제18권1호
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• pp.129-138
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• 2001

This study examined the effects of the annealing heat treatments on the mechanical properties of the Invar(Fe-36%Ni Alloy) materials. Invar materials were annealed at various temperatures range 900~120$0^{\circ}C$ in vacuum(10-4Torr) and hydrogen atmospheres. And annealing conditions were changed by cooling rate and holding time at 110$0^{\circ}C$. The grain size of rolled Invar materials was very fine but those of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere increased with increasing annealing temperature. The micro-vickers hardness values of annealed Invar materials were decreased about 15% that of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions. The tensile strength and yield strength of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere were decreased 10.0~14.4% and 34.6~39.1% those of the rolled Invar materials, respectively. The strength ratio(tensile strength/ yield strength) of annealed Invar materials was improved to 1.7~1.8 from the value of 1.2~1.3 of rolled Invar materials. The degree of spring back of annealed Invar materials was about 50% of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions.

• Design & Manufacturing
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• 제15권2호
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• pp.63-69
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• 2021

Springback is an essential task to be solved in order to make high-precision products in sheet metal forming. In this study, materials with four different elastic regions were used. For the forming analysis, the change of springback caused by the frictional force generated in the flange part during hat shape forming was considered by using the AutoForm analysis program. Factors affecting frictional force were blank holder force, friction coefficient, bead R and bead height. As a result of the forming analysis, the springback increases as the material with a larger elastic region increases. In addition, as the frictional force of the flange part increased, the tensile force in the forming direction increased and the springback decreased. In particular, the blank holder force and friction coefficient had a great effect on springback in mild materials (DC04, Al6016), and the bead effectively affects all materials. Through this study, it was considered that the springback decreased as the material with a smaller elastic region and the tensile force in the forming direction increased.

• Geomechanics and Engineering
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• 제30권3호
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• 한국식품조리과학회지
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• 제1권1호
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• pp.45-52
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• 1985

감자의 품종별 조리특성을 알아보기 위하여 춘작 4 종(남작, 대지, 도원 및 수미)과 하작 4종(남작, 수미빈체 및 라도사)을 선택하여 전분의 특성과 수우프의 점도와 식미를 측정하였다. 감자전분의 아밀로그람 특성을 품종에 따라 큰 차이를 보여 주었다. 춘작은 breakdown이나 setback 이나타나지 않고 연차적으로 점도가 상승하였으며, 호화개시 온도가 높았다. 하작의 빈체와 작은 호화가 쉽게 일어나며, breakdown 이 나타났다. 하작은 호화개시온도가 춘작에 비해 낮으므로, 전분입자가 치밀하지 못함을 유추할 수 있다. 수우프의 점도를 비교하면, 춘작의 수미, 대지 및 도원은 수우프의 온도가 내려감에 따라 점도상승이 뚜렷하나, 춘작의 남작과 하작 4종은 상승폭이 작았다. 으깬감자와 수우프의 식미검사를 보면 춘작에서는 남작이 가장 우수하였으며, 하작에서는 수미가 가장 높은 점수를 보였다. 감자의 농도에 따라 수우프의 맛은 달라지는데 춘작의 대지, 도원 및 수미는 19.8％와 23.5％ 농도에서 우수하였으나, 하작감자와 춘작의 남작은 27％농도에 서 우수하였다.

• 융합정보논문지
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• 제9권12호
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• pp.39-46
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• 2019

엔터프라이즈 환경의 표준화 경쟁은 백엔드의 데이터 티어로 시작하여 대표적인 엔터프라이즈 미들 티어가 스프링 프레임워크로 받아들여짐으로써 표준화로 안정화되고 있는 실정이다. 또한 점차 빠른 주기로 새로운 디바이스의 출현으로 웹과 모바일 서비스에 대한 호환성 확보가 웹 서비스 기업들의 중요한 경쟁력이 되고 있다. 그러나 국내 기업들은 이러한 정보화 시대의 격변한 환경 변화에 적절한 역량있는 기술 인력을 확보하지 못하고 있으며, 교육중심 대학들의 교육과정에서도 새로운 역량중심의 교육과정의 요구를 반영하지 못하고 있는 실정이다. 따라서 본 연구에서는 이러한 엔터프라이즈 시스템 플랫폼 환경에서 필요한 역량중심의 기술을 습득과 교육과정을 개발하기 위하여 스프링 프레임워크 환경에서 스프링 데이터 JPA를 활용한 시스템을 분석 및 설계 단계별로 문서화 작성을 통하여 구현하였다. 향후 엔터프라이즈 환경에서의 바로 적용할 수 있는 풀 스택 역량중심의 교육과정 및 캡스톤 디자인 교육과정의 참조 모델을 제공하고자 한다.

• 한국대기환경학회지
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• 제20권4호
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.

• 한국환경복원기술학회지
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• 제14권1호
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• pp.121-132
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• 2011

Removal rates of $NO_3$-N and TN in the free-water surface wetland system during winter; December, January, February and March, spring and fall; April, May, October and November, and summer; Jun, July, August and September were investigated. The system was established on floodplain in the downstream reach of the Gwangju Stream in 2008. It measures 50 meters in length and 5.5 meters in width. Iris pseudacorus L. grown in pots for about two years were planted in the system. The water stream was funneled in by gravity and its effluent was discharged back in. Volumes and water quality of inflow and outflow were analyzed from December 2008 to November 2010. The inflow was averaged approximately 350 $m^3/day$ and hydraulic residence time was about 3 hours. Average influent and effluent $NO_3$-N concentration was 3.75 and 3.35 mg/L, respectively and $NO_3$-N retention was amounted to 10.6%. Influent and effluent TN concentration were averaged 4.93 and 4.30 mg/L, respectively and TN abatement reached to 12.9%. One-way ANOVA statistics claimed that the average removal rates of $NO_3$-N and TN during winter, spring and fall, and summer were not always the same (p<0.001). The t-Tests of three pairs among $NO_3$-N removal rates of winter, spring and fall, and summer illustrated that the removal rates of winter ($5.04{\pm}1.94$), spring and fall ($10.53{\pm}2.24$), and summer ($18.61{\pm}2.26$) were significantly different each others (p<0.001). Among TN removal rates, the three pairs of t-Tests of three seasons showed that the removal rates of winter ($5.21{\pm}2.51$), spring and fall ($11.71{\pm}3.12$), and summer ($21.53{\pm}4.86$) were significantly different from each others (p<0.001).

• 혜화의학회지
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• 제25권1호
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• pp.119-132
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• 2016

Objectives : The aim of this study is to investigate the effect of natural carbonated hot spring water (NCHW) on DNCB-induced NC/Nga mice, an atopic dermatitis (AD) model. Methods :At first, NC/Nga mice were prepared and induced to have atopic lesion on their back skin by dinitrochlorobenzene (DNCB). They swam for 20 minutes everyday in tanks where the one is filled with $28^{\circ}C$ NCHW, the other is with $25^{\circ}C$ carbonated hot spring water and another is with artificial carbonated hot spring water (ACHW). After 3 weeks, We assessed the skin clinical score and macroscopic appearance, total IgE, IgG1 levels, WBC differential counting, IFN-${\gamma}$, IL-4, IL-13, TNF-${\alpha}$ production levels and histological changes. Results : There are meaningful results of improving atopic lesion-state by relieving the count of total IgE, IgG1 levels, WBC differential counting, IFN-${\gamma}$, IL-4, IL-13, TNF-${\alpha}$ production levels and recovering skin clinical score in the group with $28^{\circ}C$ NCHW in comparison with the other groups. Conclusions : The NCHW may have potential as an effective treatment for atopic dermatitis.

• 복식
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• 제61권9호
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• pp.97-113
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• 2011

To develop the work clothes for the employees in the mechatronics industry in South Korea, a questionnaire survey on many aspects of the work clothes such as type, color, detailed design and function preference of the subject employees has been carried out in the study. The results throughout the survey highlighted certain functions such as extensibility, thermal and air permeability of importance for the work clothing performance. To improve the discomfort caused by some work motions (i.e. squatting down, ascending/descending the stairs, raising arms), more allowances were given to the measurements (i.e. body rise + 2cm and crotch depth + 1cm for squatting down pose; thigh circumference + 1cm and knee circumference + 1cm for ascending/ descending the stairs pose; chest circumference + 5~6cm and jumper length to the level of hip circumference line for raising arms pose) for work clothes patternmaking. The evaluation of the two types of spring/summer and winter work clothes' clothing comfort and wearer mobility suggested certain points to improve the clothing performance (e.g. ventilation slits on the back pleats, arm pits and collar band of the spring/summer suit using net material and lining for the winter suit using quilted thermal materials) and wearer mobility (e.g. pants hem buckles for the easy work motion), which also enabled to fulfill the workers' work clothes design preference.