• 대한수학회지
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• 제43권3호
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• pp.507-528
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• 2006

In this paper we show that the Koecher's Jordan automorphic generators of one variable on an irreducible symmetric cone are enough to determine the elements of scalar multiple of the Jordan identity on the attached simple Euclidean Jordan algebra. Its various geometric, Jordan and Lie theoretic interpretations associated to the Cartan-Hadamard metric and Cartan decomposition of the linear automorphisms group of a symmetric cone are given with validity on infinite-dimensional spin factors

• 한국지반공학회논문집
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• 제24권11호
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• pp.133-141
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• 2008

본 연구는 피에조콘관입시험(CPTu) 결과를 이용한 점토의 비배수전단강도 평가에 관한 것으로서, CPTu 시험결과로부터 발생할 수 있는 불확실성을 최소화하고 보다 경제적이며 효과적인 비 배수전단강도 평가법 개발을 목적으로 한다. 이를 위하여 국내 남해안 지역의 해성 점토지반을 대상으로 하여, 다양한 현장 및 실내시험을 수행하였다. 제안된 방법에서는 기존 방법에 포함되어 있는 상재압(${\sigma}_{v0}$)의 보정절차가 요구되지 않으며, CPTu 결과인 콘지지력($q_t$)과 초기간극수압($u_i$)의 측정만으로 비배수전단강도의 추정이 가능하도록 하여, 조사과정에서의 추가비용이나 시간소모를 최소화하도록 하였다. 제안된 방법의 적온성 평가를 위하여 국내의 다양한 토질특성을 나타내는 4개 지역에서 수행된 피에조콘관입시험 결과를 수집하였으며, 이를 토대로 제안된 방법에 의한 결과와 실측된 결과와의 비교분석을 실시하였다. 분석결과, 예측된 결과는 측정된 결과와 유사함을 확인할 수 있었다.

• 한국지반공학회논문집
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• 제23권8호
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• pp.77-85
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• 2007

본 연구에서는 선정된 부산 신항만 공사 지역의 연약 점토층을 대상으로 비배수전단강도 값을 분석하고 CPT적용을 위한 콘계수의 변화특성 및 영향인자를 비교분석하고자 한다. 이를 위해 다양한 현장시험과 실내시험 결과를 분석하였으며, 현장시험에서 구해진 콘계수와 실내시험에서 얻어진 결과를 토대로 한 이론적인 콘계수와의 비교를 통해 해당 현장에 가장 적합한 이론식을 선정하고자 한다. 본 연구에서 사용된 이론식은 Baligh(1975)와 Yu(1993)의 공동 확장 이론과 Teh and Houlsby(1991)와 Yu 등(2000)의 정적 상태 해석법이 사용되었으며, 공동 확장 해석법이 현장 시험을 통해 측정된 콘계수와 부합하는 결과를 나타내었다.

• 한국농공학회논문집
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• 제65권5호
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• pp.1-11
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• 2023

Due to climate change and aging of reservoirs, damage to embankment slopes is increasing. However, the safety diagnosis of the reservoir slope is mainly conducted by visual observation, and the time and economic cost are formidable to apply soil mechanical tests and slope stability analysis. Accordingly, this study presented a predicting method for the compaction and strength characteristics of the reservoir embankment soil using a portable static cone penetration test. The predicted items consisted of dry density, cohesion, and internal friction angle, which are the main factors of slope stability analysis. Portable static cone penetration tests were performed at 19 reservoir sites, and prediction equations were constructed from the correlation between penetration resistance data and test results of soil samples. The predicted dry density and strength parameters showed a correlation with test results between R² 0.40 and 0.93, and it was found to replace the test results well when used as input data for slope stability analysis (R² 0.8134 or more, RMSE 0.0320 or less). In addition, the prediction equations for the minimum safety factor of the slope were presented using the penetration resistance and gradient. As a result of comparing the predicted safety factor with the analysis results, R² 0.5125, RMSE 0.0382 in coarse-grained soil, R² 0.4182 and RMSE 0.0628 in fine-grained soil. The results of this study can be used as a way to improve the existing slope safety diagnosis method, and are expected to be used to predict the characteristics of various soils and inspect slopes.

• Journal of Biosystems Engineering
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• 제6권1호
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• pp.48-59
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• 1981

The major limiting factor on the determination of combine capacity is the frequent occurence of clogging over the some parts of machine when the crop is wet in the case of Japanese self-feeding type combine. And in the case of American conventional combine having big separating parts, the great grain loss and damage occur when the machine is used for rice harvesting. This experiment was carried out to develop the new type threshing and separating equipment. Proto-type thresher which consist of a conical threshing drum and a conical separating sieve rotating around the threshing cone was constructed and tested. In the case of 800 rpm of threshing cone speed, average threshing loss was below 1 percent, separating loss was about 1 percent, grain damage was about 0.4 percent, and average total power required was about 2.6 PS. This design has some problems such as higher power required or wrapping problems under the conditions of feeding long damp straw. But, compared with the conventional combine or thresher, this machine certainly has some potentials for this approach to combine development. The crop feed rate must be increased through improvement of the feeding portion of the threshing cone. And it is required to investigate further about some parameters causing wrapping phenomena.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5957-5962
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• 2011

본 연구에서는, 시화지구 북동지역 지반에 대하여 네 가지 종류의 콘계수 값들($N_{kt}$, $N_{ke}$, $N_{{\Delta}u}$, 최근 제안된 $N_e$)과 지반의 특성치들과의 관계를 고찰하였다. 다양한 실험결과를 활용하여 계산한 비배수강도와 실제 측정된 비배수강도를 비교하였으며, 이들 값들과 소성지수와의 관계를 분석하였다. $N_{{\Delta}u}$를 활용하여 구한 비배수강도는 의외로 좋은 결과를 보여주지 못했으며, 소성지수 값이 커질수록 콘계수 값이 커지는 현상이 고찰되었다.

• 한국자원식물학회지
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• 제32권4호
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• pp.275-281
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• 2019

The pathological condition of excessive melanogenesis causing freckles, melasma, senile lentigo, pigmented acne scars, and cancer has a critical impact on the wellness of individuals. The mechanism of melanogenesis is related to the expression of melanogenic enzymes. Here, we evaluated the inhibitory effect of pine cone (Pinus densiflora) extracts on melanogenesis. P. densiflora, the Korean Red Pine, is the predominant tree species in the cool, temperate forests of northeast Asia, occurring in pure stands across Korea, Japan, and parts of northern China and Russia. P. densiflora leaves, pollen, and bark have been widely used for traditional medicine, or edible purposes. However, pine cones are rarely used as natural raw materials, although they contain many bioactive phytochemicals. The pine cone ethyl acetate fraction (PEF) showed no toxicity to B16F10 cells at a concentration of less than $100{\mu}g/mL$. PEF inhibited the expression of microphthalmiaassociated transcription factor (MITF), tyrosinase and tyrosinase-related factors in B16F10 cells treated with 3-Isobutyl1-methylxanthine (IBMX). These results suggest that pine cones can be used as an effective natural melanogenesis inhibitory agent.

• 대한방사선치료학회지
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• 제8권1호
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• pp.29-35
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• 1996

We are often faced with the clinical situations that is inevitably extended SSD for electron beam therapy due to anatomical restriction or applicator structure. But there are some difficulties in accurately predicting output and properties. In electron beam treatment , unlike photon beam the decrease in output for extended SSD does not follow inverse-square law accurately because of a loss of side scatter equilibrium, which is particularly significant for small cone size and low energies. The purpose of our study is to analyze the output in changing with the energy, cone size, air gap beyond the standard SSD and to compare inverse-square law factor derived from calculated effective SSD, mominal SSD with measured output factor. In addition, we have analyzed the change of PDD for several cones with different SSDs which range from 100cm to 120cm with 5cm step and with different energies(6MeV, 9MeV, 12MeV, 16MeV, 20MeV). In accordance with our study, an extended SSD produces a significant change in beam output, negligible change in depth dose which range from 100cm to 120cm SSDs. In order to deliver the more accurate dose to the neoplastic tissue, first of all we recommend inverse-square law using the table of effective SSDs with cone sizes and energies respectively or simply to create a table of extended SSD air gap correction factor. The second we need to have an insight into some change of dose distribution including PPD, penumbra caused by extended SSD for electron beam therapy.

• 한국화재소방학회논문지
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• 제33권4호
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• pp.35-40
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• 2019

본 연구에서는 콘 칼로리미터의 발열량 산출 값에 대한 신뢰성 평가를 위한 기초 연구로 산소소모지수법의 주요 인자인 질량유량에 관한 측정 불확도 관계식을 분석하였다. 본 연구에서 사용한 콘 칼로리미터의 덕트는 길이가 5 m이고 직경이 0.2 m로 내부가 완전히 빈 공간인 경우와 기공의 직경이 3 mm인 격자망 그리고 기공의 직경 10 mm와 기공률 0.76인 허니컴 형상의 덕트를 각각 제작하였다. 덕트 내부로 유입되는 질량유량을 산출하기 위해서 양방향 차압계와 온도센서를 유동의 수직방향으로 균일한 위치에 4개씩 설치하였으며, 레이놀즈 수 증가에 따른 속도구배와 유동의 섭동을 측정하였다. 그 결과 흡입용량이 증가할수록 난류강도에 비례하여 세 가지 형상 모두 속도구배가 증가하였으며, 95% 신뢰수준에서 질량유량에 대한 확장 불확도의 편차는 완전히 빈 공간, 격자망(d_p = 3 mm) 그리고 허니컴(d_p = 10 mm, 𝜖 = 0.76) 순으로 낮게 나타났다. 주목할 만한 점으로는 송풍기의 흡입용량이 가장 높은 조건일 때 격자망(d_p = 3 mm)이 허니컴(d_p = 10 mm, 𝜖 = 0.76) 형상에 비해서 흡입용량의 저항성은 높은데 비해서 질량유량의 확장불확도는 오히려 증가하였으며, 본 연구의 결과는 콘 칼로리미터의 덕트 내부 유동 안정성 향상을 위한 설계 자료의 활용이 가능할 것으로 판단된다.

• 한국분무공학회지
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• 제16권1호
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• pp.27-36
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• 2011

The impact force on the single and overlap region of twin spray was experimentally evaluated using visualization method in full cone type swirl nozzle spray. Visualization of spray was conducted to obtain the spray angle and breakup process. The photography/imaging technique, based on Particle Image Velocimetry (PIV) using high-speed camera, was adopted for the direct observation of droplet motion and axial velocity measurement, respectively. Droplet size was measured by Particle Motion Analyze System (PMAS). The purpose of this study is to provide fundamental information of spray characteristics, such as impact force, for higher etching factor in the practical wet etching system. It was found that the spray angle, axial velocity and impact force were increased with increasing the nozzle pressure while droplet size decreased with increasing the nozzle pressure. Droplet size increased as the distance from nozzle tip was decreased. The impact force of twin spray in the overlap region was about 63.29, 67.02, 52.41% higher than that of single spray at 40, 50 and 60 mm of nozzle pitch, respectively. Also, the nozzle pitch was one of the important factors in the twin spray characteristics.