• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.185-188
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• 2008

This paper introduces the Bootstrap method for statistical analysis of noise and vibration spectrum in aeronautic and space fields. Generally, all components of a launch vehicle and its payloads are subjected to high intensive noise and vibration environment during the lift-off phase and the ascent phase through Mach =1 and Max Q. In order to verify their survivabilities against these severe vibroacoustic environments during qualification tests and acceptance tests, it is most important to estimate the proper upper limits of the environmental condition. Although NASA has typically utilized the Normal Tolerance Limit method in deriving these levels, the reference[1] says that the Bootstrap can be also an alternative method to estimate the maximum expected environments. In this paper, a general procedure of the Bootstrap method is summarized, and it is applied to analyze acceleration power spectral density functions, which were measured during acoustic test on the upper stage of KSLV-I.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.101-108
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• 2012

본 연구 결과는 해상풍력발전시스템 타워 내부에 설치하는 서비스리프트의 설계 및 구조해석에 대한 내용이며, 공학적 설계법 및 수치해석에 의한 구조해석을 통하여 서비스리프트의 안정성 및 신뢰성을 확인하였다. 설계의 주된 내용은 설계 허용한계 이내에서 만족스러운 성능으로 지상으로부터 타워상부의 해상풍력터빈 너셀까지 작업자와 수리보수용 장비를 안전하게 수송할 수 있는 충분한 능력을 확보하는 것이다. 구조해석을 통하여 서비스리프트 캐빈 및 안전장치의 총변형량과 등가응력에 대해서 검토하여 설계 시 적용한 안전율의 타당성을 검토하였다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.5-5
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• 2017

Too little and too much water due to climatic events is a significant cause of global food insecurity. Crops are less productive under water-limited conditions and all major crops, with the exception of rice (Oryza sativa), die within a few days of complete submergence. To complement our studies on genes such as SUB1A, (an ERF-VII transcription factor that provides robust submergence tolerance) and AG1 (a TREHALOSE 6-P PHOSPHATASE that promotes establishment of young seedlings underwater), we have retooled INTACT (${\underline{I}}solation$ of ${\underline{N}}uclei$ ${\underline{TA}}gged$ in specific ${\underline{C}}ell$ ${\underline{T}}ypes$) and TRAP (${\underline{T}}ranslating$ ${\underline{R}}ibosome$ ${\underline{A}}ffinity$ ${\underline{P}}urification$) for rice. These technologies enable us to follow dynamics in chromatin, nuclear pre-mRNAs and ribosome-bound mRNAs in meristems and diverse cell types. With these technologies we can better interpret responses to stresses and reestablishment of homeostasis. These include stress acclimation strategies involving changes in metabolism and development, such as dynamics in suberin deposition in sub-epidermal layers of roots that limit water loss under drought and oxygen escape during waterlogging. Our new data uncover dynamic and reversible regulation at multiple levels of gene regulation and provide new insights into processes of stress resilience. Supported by US NSF-PGRP Plasticity (IOS-1238243), Secretome (IOS-1546879) and REU (DBI-146129) grants.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.675-680
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• 2006

This is a study of fatigue strength of weld deposits with transverse cracks in plate up to 50 mm thick. It is concerned with the fatigue properties of welds already with transverse cracks. A previous study of transverse crack occurrence, location and microstructure in accordance with welding conditions was published in the Welding Journal (Lee et al., 1998). A fatigue crack develops as a result of stress concentration and extends with each load cycle until fatigue occurs, or until the cyclic loads are transferred to redundant members. The fatigue performance of a member is more dependent on the localized state of stress than the static strength of the base metal or the weld metal. Fatigue specimens were machined to have transverse cracks located on the surface and inside the specimen. Evaluation of fatigue strength depending on location of transverse cracks was then performed. When transverse cracks were propagated in a quarter-or half-circle shape, the specimen broke at low cycle in the presence of a surface crack. However, when the crack was inside the specimen, it propagated in a circular or elliptical shape and the specimen showed high fatigue strength, enough to reach the fatigue limit within tolerance of design stresses.

• 한국수산과학회지
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• 제53권5호
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• pp.725-732
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• 2020

The sudden drop of water temperature in winter is very threatening factor that affects the productivity of farmed fish and the management in aquafarm. In this study, we investigated the effect of low temperature on the survival, oxygen consumption and stress responses of parrotfish Oplegnathus fasciatus due to acute drop of water temperature. The survival rate of parrotfish Oplegnathus fasciatus was 5% at 6℃, 95% at 8℃ and 100% at 10℃ on the 4^th day of exposure in each experimental temperature. Low-lethal temperature for 4days of parrotfish Oplegnathus fasciatus (4 day-LT₅₀) was 6.99℃ (confidence limit, 6.55-7.42℃). Oxygen consumption rate was significantly decreased with decreasing water temperature. Temperature coefficient (Q₁₀) was found to be 4.0 between 10℃ and 8℃ and 0.39 between 8℃ and 6℃. As a result of investigating the stress response according to the drop in water temperature, the concentration of SOD (Superoxide dismutase), cortisol, glucose, total Ig, AST (Aspartate) and ALT (Alanine aminotransferase) increased with decreasing of water temperature. This study would be useful for the management of temperature about cultured fish.

• Management Science and Financial Engineering
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• 제12권2호
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• pp.87-110
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• 2006

In a hierarchical road network, all roads can be classified according to their attributes such as speed limit, number of lanes, etc. By splitting the whole road network into the subnetworks of the highlevel and low-level roads, we can reduce the size of the network to be calculated at once, and find a path in the way that drivers usually adopt when searching out a travel route. To exploit the hierarchical property of road networks, we define a convenient path and propose an algorithm for finding convenient paths. We introduce a parameter indicating the driver's tolerance to the difference between the length of a convenient path and that of a shortest convenient path. From this parameter, we can determine how far we have to search for the entering and exiting gateway. We also propose some techniques for reducing the number of pairs of entries and exits to be searched in a road network. A result of the computational experiment on a real road network is given to show the efficiency of the proposed algorithm.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.74-80
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• 2005

It becomes necessary for engine manufactures to verify whether lots of engines on test bed during shop test are in compliance with NOx Technical Code for marine diesel engines more efficiently on the basis of engine group test concept which contains parent engine and member engines since all the engines are not needed to take NOx measurement. In addition, it becomes more obliged to consider parameters which affect NOx emission level and describe these parameters in NOx technical file as engine information and settings to define engine operation range with tolerance to make sure the engines are still in compliance with NOx emission limit on board after shop test. During preparation of engine group test for 4-stroke marine diesel engines, we evaluated NOx emission value under different engine operating conditions and found that there are certain parameters, for example, Charge air temperature and Max. cylinder pressure which have influence on NOx emission level. The NOx emission shall be satisfied with NOx technical code by means of controlling such parameters.

• 산경연구논집
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• 제9권4호
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• pp.27-35
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• 2018

Purpose - The purpose of this research is to verify mediation effects of finance stress within relation structure between income inequality recognized by the elderly and life satisfaction. Research design, data, and methodology - In order to achieve the purpose of this research, we investigated recognition of income inequality of the elderly, finance stress and life satisfaction by using examination data aimed at 541 elderly people whose age is over 65 living in Chungcheongbuk-do. We conducted reliability, correlation, regression analysis_(tolerance limit and variance inflation factor) by using SPSS ver. 18.0. Results - From the result of analysis, it was proved that there are mediation effects of finance stress within the relation between income inequality recognized by the elderly and satisfaction with life. Based on this result, we suggest practical and political proposals to increase life satisfaction of the elderly. Conclusions - The purpose of this research is to verify mediation effects of finance stress in the relationship between income inequality and life satisfaction recognized by the elderly. From the result of research, first, a direct effect was discovered that as income inequality becomes high, life satisfaction will be decreased. Second, partial mediation effect of finance stress was confirmed in the relationship between income inequality and life satisfaction.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.254-263
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• 2015

The failure of hydraulic turbine runners is a rare event. So in order to assess the reliability of these components one cannot rely solely on the number of observed failures in a given population. However, as there is a limited number of degradation mechanisms involved, it is possible to use physically-based reliability models. Such models are often more complicated but are able to account for physical parameters in the degradation process. They can therefore help provide solutions to improve reliability. With such models, the effect of materials properties on runner reliability can be highlighted. This paper presents a brief review of the Kitagawa-Takahashi diagram which links the damage tolerance approach, based on fracture mechanics, to the stress or strain-life approaches. Using simplified response spectra based on runner stress measurements, we will show how fatigue reliability is sensitive to materials fatigue properties, namely fatigue crack propagation behaviour and fatigue limit obtained on S-N curves. Furthermore, we will review the influence of the main microstructural features observed in 13%Cr-4%Ni stainless steels commonly used for runner manufacturing. The goal is ultimately to identify the most influential microstructural features and to quantify their effect on fatigue reliability of runners.

• 대한수의학회지
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• 제37권1호
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• pp.203-212
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• 1997

Antibacterial efficacy and safety of copper sulfate pentahydrate (5% solution) was evaluated in laboratory and field studies for disinfection of some fish bacterial pathogens in cultured fish, flounder(Paralichthys olivaceus), mirror carp(Cyprinus carpio), gold fish(Carrassius auratus) and eel(Anguilla japonica). Dipping of fishes for acute toxicity was performed for a period of 48h, and the TLm value(median tolerance limit) were 4.0ppm in mirror carp and flounder, 4.4ppm in rainbow trout, and 10.0ppm in gold fish. After exposure below than TLm value for 1 month, no side effects and histopathological changes were observed. The test drug were shown high antibacterial activities against most bacterial pathogens by exposure in the laboratory and field trials. However, Aeromonas salmonicida showed a resistance to the dosage. We can prevent outbreaks of bacterial diseases of fish by the dosage of 1ppm for 6hr and the test drug is thought to be used effectively and widely as a disinfectant against most bacterial fish pathogens.