• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.65-65
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• 2017

밭작물 중 양파와 마늘은 높은 노동투하시간, 노임의 상승, 복잡한 수거 과정 등으로 최근 재배면적이 감소하는 추세이다. 밭농업 활성화 방안으로 생산비 절감과 작업 속도 향상을 위한 수확기계 개발 연구로 줄기절단기가 개발되었다. 이 연구는 줄기절단기 예취날의 설치각이 절단부하에 미치는 영향을 분립체 해석 기법으로 분석하고자 하였다. 실험에 사용한 시뮬레이션은 EDEM으로 인장탄성계수, 전단탄성 계수, 중첩길이, 입자 반경 및 질량, 상대속도를 이용하여 충돌시 힘을 해석하고 인장 및 전단강도, 한계, 결합 길이를 통해 입자간 결합을 설정할 수 있다. 시제품으로 설계된 줄기절단기의 치수를 활용하여 프로그램 상에서 줄기 절단 시뮬레이션을 진행하여 절단부하 결과를 얻도록 하였고 칼날 설치각을 30도, 45도, 60도로 변경하여 각각의 부하를 분석하여 경향성을 파악하고자 하였다. 실험에서 사용한 프로그램은 EDEM 2.7.1 Academic Research 버전이며 시뮬레이션을 진행한 PC의 사양은 Intel(R) $Core^{TM}$ i7-4790 CPU @ 3.60GHz, Memory 16.0GB이다. 줄기 절단 시뮬레이션에 적용시킨 줄기 모델은 마늘의 조건을 적용시켜 직경 1mm의 입자로 이루어진 지름 12mm, 높이 214mm의 원통형 모델이며 60.32N의 최대절단력을 가지고 있다. 줄기절단기는 2개의 회전날을 가지고 있으나 좌우대칭을 적용하여 절반에 대한 해석으로 하나의 회전날로 절단을 하도록 줄기 모델은 4조로 하여 3열을 140mm 간격으로 위치시켰다. 줄기절단기의 칼날은 반경 350mm로 회전하며 진행속도는 1.65m/s, 회전속도는 1680rpm으로 작업하도록 하였다. 시뮬레이션은 0.5초의 시간에 대해 해석하도록 하였으며 0.003초 간격으로 칼날에 가해지는 힘을 구하여 저장하도록 하였다. 시뮬레이션 해석시간은 약 116시간이었으며 설치각별 시간에 따른 칼날에 가해지는 압축력 값과 그래프를 얻을 수 있었다. 대부분의 시간에서 절단이 이루어지지 않으므로 0의 값을 나타내었으며 절단이 이루어지는 시점에 절단부하가 나타났다. 결과 해석을 위해 그래프의 피크 값들을 이용하였으며 그 중 상위 6개의 값으로 분석하였다. 30도, 45도, 60도의 설치각에 따른 절단부하의 평균 값은 각각 105.4N, 160.5N, 215.9N으로 나타났다. 설치각에 따른 절단부하의 경향성은 유의수준은 3.93%로 각각의 차이가 유의미하게 나타났으며 상관계수는 0.489로 증가하는 경향이 보였다. 그러나 $R^2$는 0.2394로 낮은 값을 보여 데이터 처리 방법의 개선과 적절한 회귀 모델의 적용이 필요하다. 향후 포장시험을 진행하고 복합적으로 분석하여 경향성을 자세히 분석하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.342-347
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• 2000

새로운 칼라 영상 압축은 순간 포착과 블록절단 코딩에 기초로 두 개의 대표적인 칼라 중 하나로 할당된 각각의 블록 화소와 겹치지 않은 블록으로 분할된 입력은 블록에서 포착된 어떤 순간으로부터 유래된 해석방식으로 계산된다. 비트맵은 화소의 칼라를 묘사하기 위해 각각의 블록을 일반화하며 별개의 균일한 조건에 의해 설정된 대표적인 칼라는 동일하다고 간주되고 부호 비트를 저장하기 위해 이용된다. 본 연구에서 실험결과에 의해 13이상의 좋은 평균 압축률이 달성될 수 있었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.16-22
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• 2012

We performed impact test to estimate necessary explosive charge weight for cutting the cable whose diameter is 22 mm. The impact test results were analyzed by Probit method. The cutting energy was calculated 37.7 J with 99.99% probability at 99% reliability compared to the average energy of 24.9 J. The cable was cut 3 times without failure with 150 mg of Zirconium Potassium Perchlorate (ZPP), which was considered to generate 24.5 J of mechanical energy with assumption that only 10% of explosive energy converts to mechanical energy. The calculated energy from measured pressure with 150 mg ZPP was 26.1 J, which is almost same with both impact test result and expected mechanical energy. We can argue that the cable can be cut with 99.99% probability at 99% reliability by 230 mg of ZPP.

• International Area Studies Review
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• v.14 no.2
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• pp.3-23
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• 2010

The purpose of the study is to estimate value of the Eulsukdo that is attracting lots of birds. Eulsukdo became one of the most famous eco-tourism destinations worldwide and environmental restoration work is progressing with enormous budget. The input of the budget by policy judgement basically can be justified when the benefit excesses the cost in social aspect. Eulsukdo has external effect as cultural tourism resource but it is difficult to estimate the value in market. The study is to estimate the value of Eulsukdo through the single-bounded dichotomous CVM(Contingent Valuation Methods). According to analysis results, the mean WTP(Willingness to Pay) and the truncated mean WTP are estimated at 5,240 and 3,374 won in the log-normal model, and 5,888 and 3,232 won in the log-logistic model respectively. The annual total benefits value based on the truncated mean WTP is estimated at 3,870 million won in the log-normal model and 4,040 million won in log-logistic model. The result of this study will provide useful guide to policy makers and developers who fully realize the value of public goods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.649-658
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• 1995

In order to estimate the level of genetic differences among the pleuronectid species, mitochondrial DNAs were isolated from four species: brown sole, Limanda herensteini; marbled sole, Limanda Yokohamae; stone flounder, Kareius bicoloratus; starry flounder, Platichthys stellatus, and the number of nucleotide substitutions was calculated by the restriction fragment length polymorphisms (RFIPs) generated by f4 sin base recognition restriction endonucleases. Total lengths of the mitochondrial DNA were measured as about 17.6 kbp in all species. Ten different composite genotypes were observed in brown sole, four different genotypes in marbled sole, and two different genotypes in starry flounder. However, only one genotype was observed in stone flounder. The calculated haplotypic diversity value of brown sole was higher than that of marbled sole. The average number of nucleotide substitutions per sites in four species was estimated to be 0.0045 in the intraspecies, 0.0344 in the interspecies, and 0.0457 in the genera, respectively. From these results, we could estimate that the genetic differences among interspecies were not influenced by nucleotide substitutions but genetical discontinuous.

• Journal of Chest Surgery
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• v.35 no.3
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• pp.223-226
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• 2002

Background: Thoracoscopic sympathicotomy is an effective treatment in essential hyperhidrosis. However, many patients suffer from compensatory hyperhidrosis. Compensatory hyperhidrosis is a very uncomfortable problem, but the mechanisms underlying compensatory hyperhidrosis are not completely understood. Material and Method: From May 1999 to June 2001, 25 cases of thoracoscopic sympathicotomy at the 2nd rib for facial hyperhidrosis and 116 cases of thoracoscopic sympathicotomy at the 3rd rib for palmar hyperhidrosis were performed in 141 patients. All of the patients were divided into noncompensatory sweating(NCS) and compensatory sweating(CS) group. Each group was investigated according to age, sex, body surface area(BSA), level of sympathicotomy and occupation. Result: The global rate of compensatory hyperhidorsis were 64.5%(91/141). There was no difference between the two groups for BSA, level of sympathicotomy and occupation. Mean age showed 23.2 years old in NCS group and 26.4 years old in CS group(p=0.09). In CS group, 46 cases were male(50.5%) and 45 cases were female(49.5%) and in NCS group, 19 cases were male(38.0%) and 31 cases were female(62.0%) (p=0.16). Conclusion: There were no available statistical data, but there was the fact that old age and male patients had the tendency for compensatory hyperhidrosis. If we have more patient group and consider the patient's family history or psychiatric problems, we will have more valuable data for compensatory hyperhidrosis.

• Journal of Korea Water Resources Association
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• v.37 no.1
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• pp.13-19
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• 2004

This study shows the possible use of the Poisson process for the characterization of dry year return period and duration. For the analysis we used an annual precipitation data, which has been collected since 1911 in Seoul. The highest threshold for the application of the Poisson process was determined to be the mean-0.5standard deviation, and then the results from the Poisson process are compared with the observed. Especially, the Poisson process was found to reproduce the mean duration and return interval quite well and show the possibility of using the Poisson process for the drought analysis.

• The Korean Journal of Applied Statistics
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• v.30 no.5
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• pp.647-663
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• 2017

Weibull distribution is a popular distribution for modeling lifetimes because it reflects the characteristics of failure adequately and it models either increasing or decreasing failure rates simply. It is a standard method of the lifetimes test to wait until all samples failed; however, censoring can occur due to some realistic limitations. In this paper, we propose a generalized likelihood ratio (GLR) chart to monitor changes in the scale parameter for type I right-censored Weibull lifetime data. We also compare the performance of the proposed GLR chart with two CUSUM charts proposed earlier using average run length (ARL). Simulation results show that the Weibull GLR chart is effective to detect a wide range of shift sizes when the shape parameter and sample size are large and the censoring rate is not too high.

• Journal of Chest Surgery
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• v.36 no.8
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• pp.590-594
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• 2003

Vascular injury has been increased with popular outside activities. However there are only a few studies for vascular trauma. We intended to find out the relationships between the vascular trauma and its prognosis. Material and Method: Forty-four patients were diagnosed and operated on for vascular injury in the Gyeongsang National University Hospital from 1992. to 1999. We reviewed their chart and analysed their data retrospectively. We studied to causes, treatments, and prognoses of traumatic vascular injury. Result: The transfer time between accident place and emergency department was mean 3,5 hour, and the operation preparing time was 8.8 hours. Five cases required amputation of extremity. All amputation cases were combined with communited bony fractures. Thirty-eight cases had combined other injuries, and almost combined injuries were muscular and neurological damages, Conclusion: The optimal treatment plan for vascular trauma was prompt diagnosis and quick management. It may decrease amputation rate and post-traumatic complications. Therefore we must be carefully evaluated the multiple traumatic patients for early diagnosis of vascular injury and operate quickly in emergency status.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.270-280
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• 2016

This paper investigates the evolution of EM admittance of piezoelectric transducers mounted on a notched beam from wave propagation perspective. A finite element analysis is adopted to obtain numerical solutions for Lamb waves reverberating on the notched beam. The mode-converted Lamb wave signals due to a notch are extracted by using the polarization characteristics of piezoelectric transducers collocated on the beam. Then, a series of temporal spectrums are computed to demonstrate the evolution of EM admittance through fast Fourier transform of the mode-converted Lamb wave signals which are consecutively truncated in the time domain. When truncation time is relatively small, the corresponding temporal spectrum is governed by the characteristics of the input driving frequency. As truncation time becomes large, however, the modal characteristics of the notched beam play a crucial role in the temporal spectrum within the input driving frequency band. This implies that mode-converted Lamb waves reverberating on the beam contributes to the resonance of the beam. The root mean square values are computed for the temporal spectrums in the vicinity of each resonance frequency. The root mean square values increase monotonically with respect to truncation time for any resonance frequencies. Finally the implications of the numerical observation are discussed in the context of damage detection of a beam.