• 한국태양에너지학회 논문집
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• 제32권spc3호
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• pp.262-268
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• 2012

In the recent research technical solutions have been studied to integrate renewable energy into unmanned aerial vehicles to use it as the main power source. As the weight of the aerial vehicle body is essential for its performance, we consider to use light-weight solar cell technology. Furthermore fuel cells are also integrated create a highly energy-efficient aerial robot. In this paper, construction concept and software design of the tilt-rotor aerial vehicle GAORI is introduced which uses solar cells and fuel cells as power source. The future work direction and prognosis are discussed.

• 대한의생명과학회지
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• 제10권3호
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• pp.275-283
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• 2004

The annual changes in testis weight and diameter of seminiferous tubules, and the seminiferous epithelium cycle of Tamias sibiricus were studied by light microscope. Testis weight and diameter of seminiferous tubule are significantly increased from January to July, and decreased rapidly to the size from August to December. Spermatogenesis occurs from January to July, and spermatocytogenesis are produced from August to December. The cycle of the seminiferous epithelium was divided into 12 stages during the development of spermatids as a changes of the nucleus and acrosomal structure, presence and/or absence of residual body, appearance and/or absence of sperm tail and meiotic figure and spermiation. The dark type spermatogonia (Ad) are appeared in all stages (I ~ XII), and the spermatids of step 10 are observed at I, II, X and XII stages. The spermatids of step 11 are appeared in III and IV stages, only the step 12 spermatid observed in V stage.

• 수산해양교육연구
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• 제15권1호
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• pp.123-133
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• 2003

The present investigations were carried out for the most and fundamental elements, what is called maneuverability, stability, safety, rig, sail about the world famous race, VOLVO60 and America's cup. The results obtained are summarized as follows: First, the structure of yacht should be designed with focuse on the preparation for the preparation of collision with other yachts around, with the dumps of iceberg and also whales nearby. At the same time, the accurate calculation on the each structure and equipment of yacht should be processed for the dynamic stability in the rainstorms. Second, VOLVO60, long-distance sailing, should be emphasized on the light weight and the safety, while the boat for America's cup, short-distance sailing, should be stressed on the appropriate weight of the body and the maximum speed for fast maneuverability. Third, up-to-the minute materials should be developed for the appropriate wind power and the turning of directions.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.164-169
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• 2005

The TTX(Tilting Train eXpress) is designed to achieve high driving speed up to 200 km/h and to run on conventional curved rails without speed reduction. In order to maintain power collection between catenary and pantograph collector while train body is tilted, the TTX pantograph must have tilting structure (or Sledge). The power quality is determined by the tilting structure. Static and dynamic characteristics of tilting structure, therefore, are important to evaluate the pantograph performance. The current prototype of the tilting structure is overweight model and its structural characteristics have not been investigated. In this study, the finite element model of TTX tilting structure is established and static analysis is performed. Finally, using this result, a light weight model is proposed.

• Applied Microscopy
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• 제28권4호
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• pp.551-561
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• 1998

The autometallographic method was used to demonstrate the localization of mercury deposits in spleen of mouse. The mercury deposits were identified with the light and electron mocroscope. Mice were treated with methylmercuric chloride in the drinking water (demineralized water) for 40 days. Control and mercury treated groups showed no significant differences in mean body weight and spleen weight per one mouse. Mercury grains were appeared in the germinal center of white pulp consist of a preponderancing lymphocytes, not in red pulp and capsule. At the ultrastructural level, mercury deposits were restricted to lysosomes of macrophage and lymphocyte. Specially, volume in lysosomes of the macrophage was increased. These results suggest that mercury localization in lysosomes is associated with the change of immune activity.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.773-774
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• 2016

본 논문에서는 감마선원 영상화를 위한 감마선 탐지장치에 적용할 차폐체의 경량, 소형화 연구를 수행하였다. 선행 연구를 통해 상용 감마선 영상화 장치의 차폐체와 유사한 차폐효율 및 성능을 나타내는 납 기반의 차폐체를 구현하였으며, 본 논문에서는 납 기반의 차폐체보다 경량화, 소형화를 위해 텅스텐기반의 차폐체를 설계하였다. 차폐체 설계를 위해서 MCNP 전산모사를 수행하였으며, 그 결과 17%의 경량화 및 51%의 체적을 줄이는 결과를 얻었다.

• Journal of Nutrition and Health
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• 제30권2호
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• pp.187-194
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• 1997

The effects of diet induced hyperlipidemia on kidney function were studied in Sprague-Dawley rats fed high fat diet containing 20% beef tallow and high cholesterol diet containing 5% cholesterol for 8, 12, 16 weeks, respectively. The concentrations of serum total lipid, total cholesterol and LDL-cholesterol were significantly high cholesterol diet groups during all experimental periods (p<0.05). HDL-cholesterol concentration was the lowest value in high cholesterol diet group of 16 weeks(p<0.05). Triglyceride concentration was not affected by experimental diets. Serum total protein, albumin and creatinine concentration tended to higher in high cholesterol diet groups than those in high fat diet groups. And serum urea-N concentration was higher in high fat diet group of 16 weeks than that in other diet groups. Urinary total protein and urea-N were higher in high cholesterol diet groups than those in other diet groups regardless of experimental period period. There was no significant difference in urinary creatinine concentratin among diet groups(p<0.05). GFR was lower in high cholesterol diet groups than that in high fat diet groups at 8, 16 weeks, respectively. Wet weight per body weight, total lipid, triglyceride, total cholesterol concentations of liver tissue were apparently high in high cholesterol diet groups(p<0.05). Kidney wet weight per body weight wer not affected by experimently diets, total lipid concentration of kidney tissue was significantly high in high fat diet groups of 12 weeks(p<0.05), kidney tissue triglyceride concentrations of high cholesterol diet groups of 12, 16 weeks apparently low, and total cholesterol concentration of kidney tissue was higher in experimental diet groups than that of control groups at 12, 16 weeks(p<0.05). Fecal excretion, total lipid, triglyceride and cholesterol concentrations of feces were markedly high in all high cholesterol diet groups except high fat diet group of 16 weeks. The results of light microscopic examination indicated that glomerulosclerosis was not obsrved in rats fed experimental diets.

• 한국건설순환자원학회논문집
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• 제10권1호
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• pp.111-116
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• 2022

최근 들어 건축구조물은 초고층화 및 대규모화 하는 경향에 있으며, 콘크리트 기술의 발달로 인하여 철근콘크리트 구조로 초고층 건축물을 축조하는 것이 일반화 되어 가고 있는 실정이다. 초고층 건축물에 적용되는 철근콘크리트주조는 고유동·고강도 콘크리트가 적용되기 때문에 시공성이 향상되고 단면축소가 가능하게 되었다. 또한 철근콘크리트구조의 초고층 건축물에는 슬라이딩폼, ACS(Auto Climbing Form) 등 시스템 거푸집을 적용하기 때문에 시공의 신속성을 기할 수 있으며, 철골구조보다 저렴한 가격에 내화·내진 등 우수한 품질로 빠른 시일 내에 완성할 수 있게 되었다. 그러나 초고층 건축물을 철근콘크리트 구조로 시공할 경우는 자중이 커지게 된다는 단점을 가지게 된다. 이러한 단점을 보완하고자 개발된 것이 경량골재(LWA, Low Weight Aggregate)이며, 최근까지 다양한 종류의 경량골재가 개발되어지고 있다. 이러한 경량골재를 이용하여 콘크리트를 제조하면 철근콘크리트 구조물의 자중을 줄일 수 있다는 장점을 가지게 되지만, 콘크리트의 강도가 줄어든다는 단점을 가진다. 이는 경량골재가 일반적인 천연골재에 비하여 낮은 강도를 가지고 있기 때문으로 최근에는 이러한 경량골재의 취약점을 보완하기 위한 연구가 진행되고 있다. 본 연구에서는 경량골재 표면코팅 유무에 따른 시멘트 경화체의 강도특성을 알아보기 위한 실험적 연구를 진행하였다. 그 결과, 압축강도는 표면코팅 한 경량골재가 코팅하지 않은 경량골재보다 높은 강도발현을 나타냈으며, 물/시멘트 비 50 %에서 표면코팅 경량골재가 높은 압축강도를 발현하는 것을 알 수 있었다. 이는 표면코팅 경량골재 혼입 시멘트 경화체의 계면 공극이 고로슬래그 미분말 입자로 메워졌기 때문인 것으로 확인되었다.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.114-121
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• 2010

This paper presents a design process of light-weighted fuel cell vehicle (FCV) frame to meet design target of natural frequency in early design stage. At first, using validated FE model for the current design, thickness optimization was carried out. Next. optimization process, comprised of beam model size optimization, shell model design and shell model thickness optimization, was investigated for two frame types. In addition, in order to ensure hydrogen tanks safety against rear impact load, structural collapse characteristics was estimated for the rear frame model finally produced from the previous optimization process and, with the target of equal collapse characteristics to the current design model, structural modification with small weight increase was studied through static structural collapse analyses. The same attempt was applied to the front side frame. The results explain that the proposed process enables to design light-weighted frames with high structural performance in early stage.

• Composites Research
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• 제28권5호
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• pp.291-296
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• 2015

본 연구에서는 자동차 구조물의 경량화를 위해 자연섬유 복합재료를 적용하여 차량용 패널의 구조 설계 및 해석을 수행하였다. 구조 설계를 위해 Flax/vinyl ester 복합재료를 적용하였다. 섬유 복합재 패널의 제조공법은 VARTML(Vacuum Assisted Resin Transfer Molding-Light) 제조공법이 적용되었다. 구조 설계 후 충돌에 의한 구조물의 안전성을 분석하기 위해 충돌 실험을 수행하였다. 충돌 실험은 유럽 보행자 보호 기준에 맞게 수행하였으며 해석 결과를 검증하기 위하여 시편을 제작해 충격 실험을 수행하였다. 또한 충격 손상 후 구조물의 잔류강도를 측정하기 위해 손상을 가한 시편의 압축강도 실험을 수행하였다.