• 한국정밀공학회지
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• 제3권1호
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• pp.40-49
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• 1986

Crack, craze and void are common defects which may be found in the bulk of polymeric materials such as either themoplastics or thermosets. The healing phenomena, autohesion, of these defects are known to be a intrinsic material property of various polymeric materials. However, only a few experimental and theoretical investigations on crack, void and craze healing phenomena for various polymeric materials have been reported up to date [1, 2, 3]. This may be partly due to the complications of healing processes and lacking of appropriate theoretical developments. Recently, some investigators have been urged to study the healing phenomena of various polymenic materials since the significance of the use of polymer based alloys or composites has been raised in terms of specific strength and energy saving. In the earlier published reports [1, 2, 3, 4], the crack and void healing velocity, healing toughness and some other healing mechanical and physical properties were measured experimentally and compared with predicted values by utilizing a simple model such as the reptation model under some resonable assumptions. It seems, however, that the general acceptance of the proposed modeling analyses is yet open question. The crack healing processes seem to be complicate and highly dependent on the state of virgin material in terms of mechanical and physical properties. Furthermore, it is also strongly dependent on the histories of crack, craze and void development including fracture suface morphology, the shape of void and the degree of disentanglement of fibril in the craze. The rate of crack healing may be a function of environmental factors such as healing temperature, time and pressure which gives different contact configurations between two separated surfaces. It seems to be reasonable to assume that the crack healing processes may be divided in several distinguished steps like stress relaxation with molecular chain arrangement, surface contact (wetting), inter- diffusion process and com;oete healing (to obtain the original strength). In this context, it is likely that we no longer have to accept the limitation of cumulative damage theories and fatigue life if it is probable to remove the defects such as crack, craze and void and to restore the original strength of polymers or polymer based compowites by suitable choice of healing histories and methods. In this paper, we wish to present a very simple and intuitive theoretical model for the prediction of healed fracture toughness of cracked or defective polymeric components. The central idea of this investigation, thus, may be the modeling of behavior of chain molecules under healing conditions including the effects of chain scission on the healing processes. The validity of this proposed model will be studied by making comparisons between theoretically predicted values and experimentally determined results in near future and will be reported elsewhere.

• Asian-Australasian Journal of Animal Sciences
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• 제33권12호
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• pp.1975-1984
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• 2020

Objective: The study was conducted to determine the effects of body weight (BW) and fiber sources on nutrient digestibility, fiber fermentation and short chain fatty acids (SCFA) concentration in different intestinal segments of growing pigs fed high-fiber diets. Methods: Nine barrows with initial BW of 25.17±0.73 kg and 9 barrows with initial BW of 63.47±2.18 kg were allotted to a duplicate 9×2 Youden Square design with 3 dietary treatments and 2 periods. The dietary treatments were formulated with 3 different high-fiber ingredients: corn bran, sugar beet pulp, and soybean hulls, respectively. Each diet was fed to 3 barrows with different stage of BW in each period. Results: There were no differences in the apparent ileal digestibility (AID) of most nutrients between pigs at different BW stages. Pigs at 60 kg had greater (p<0.05) apparent total tract digestibility (ATTD) of total dietary fiber (TDF), soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), and had greater (p<0.05) hindgut disappearance of IDF and cellulose than pigs at 25 kg. The acetate, propionate and total SCFA concentrations in ileal digesta and feces of pigs at 60 kg were greater (p<0.05) than those of pigs at 25 kg. In addition, fiber sources affected (p<0.05) the AID of gross energy (GE), organic matter (OM), ether extract (EE), crude protein, SDF and hemicellulose, the hindgut disappearance and ATTD of dietary fiber components, the lactate and propionate concentrations in ileal digesta and the butyrate, valerate and total SCFA concentrations in feces. There were interactions (p<0.05) between BW and fiber sources on the AID of GE, OM, EE, SDF, hemicellulose, the ATTD of EE, TDF, and IDF, and the hindgut disappearance of SDF and hemicellulose. Conclusion: Increasing BW mainly improved the digestibility of dietary fiber fractions, and the dietary fiber sources influenced the digestibility of almost all the dietary nutrients in growing pigs.

• Ocean and Polar Research
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• 제31권1호
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• pp.121-131
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• 2009

In an effort to better understand the physiological and ecological differences between warm and cold water copepod species in Korean waters using lipid contents and compositions, two species of copepods (Pleuromamma sp. as a warm water species and Neocalanus plumchrus as a cold water species) were collected from the Northwest Pacific and East Sea/Sea of Japan, respectively. The cold water species showed two fold higher lipid contents than the warm water species (11% vs. 5% of dry weight). Wax esters, known as one of the major storage lipid classes, were found to be the dominant lipid class (accounting for 64% of total lipids) in the cold water species, whereas, in the warm water species, phospholipids, which are known as membrane components, were the dominant lipid class (accounting for 43% of total lipids),with a trace amount of the storage lipids as a form of triacylglycerols (${\leq}1%$ of total lipids). With regard to the fatty acid compositions, saturated fatty acids (SAFA), especially 16:0 (about 30% of total fatty acids), were most abundant in the warm water species, whereas the polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA : 20:5(n-3)) (${\geq}16%$ of total fatty acids), were most abundant in the cold water species. Among the neutral fraction of lipids, phytol, originating from the side chain of chlorophyll and indicative of active feeding on phytoplankton, was detected only in the warm water species. Significant quantities of fatty alcohols were detected in cold water species, particularly long-chain monounsaturated fatty alcohols (i.e. 20:1(n-9) and 22:1(n-11)), which are well known to abound in cold water herbivorous copepods. However, only trace amounts of short-chain fatty alcohols were detected in the warm water species. Twelve different kinds of sterols were detected in these copepod species, with cholest-5-en-$3{\beta}$-ol (cholesterol) and cholesta-5, 24-dien-$3{\beta}$-ol (desmosterol) dominating in cold and warm water species, respectively. In addition, for the warm water species (Pleuromamma sp.), we assessed the latitudinal gradients of lipid contents and compositions using samples from three different latitudinal regions (Philippine EEZ, Japan EEZ, and the East China Sea). Although no latitudinal gradients of lipid contents were detected, the lipid compositions, particularly dietary fatty acid markers, varied significantly with the latitude. The findings of this study confirm that the distribution of lipid contents and compositions in copepods may not only indicate their nutritional condition and diet history, but may also provide insights into their living strategies under different environmental conditions (i.e., water temperature, food availability).

• 유통과학연구
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• 제13권5호
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• pp.103-111
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• 2015

Purpose - When it comes to first impressions of family restaurants, people basically think of the following factors: cozy, a refreshing space, indoor lighting, atmospheric music, the best-quality service through mutual interactions with employees, birthday events, follow-up customer management, brand image, and many others. Focusing on such family restaurants characteristics, with consumption experience and customer satisfaction determined as mediator variables, this study looks into the selection factors that affect customer loyalty when choosing a family restaurant. Subsequently, the study conducts an empirical analysis of these selection factors with the greatest influence. Research design, data, and methodology - This study analyzed 200 total surveys of family restaurant customers including college students, workers, housewives, and others. The survey was conducted over two weeks in May 2014. For statistical processing, SPSS 21 was used for factor analysis and reliability analysis as well as AMOS for structural equation analysis. In terms of a variable that would influence either consumption experience or customer satisfaction at the restaurants, the study introduced the concept of customer equity. The study designed a model based on a hypothesis developed using the following factors: customer encounter service value, customer convenience value, brand equity, relationship equity, and other factors defined as components of customer equity by Rust et al. (2000) determined as independent variables as well as with customer experience and customer satisfaction set as mediator variables. The hypothesis, after all, assumed that customer loyalty would be positively (+) influenced. Results - The analysis results from the study reported that brand value, customer encounter service value, and relationship value have positive (+) effects on consumption experience and customer satisfaction. However, as for customer convenience value, this turned out not to have a statistically significant influence on consumption experience and customer satisfaction. In regard to a relation between consumption experience and customer satisfaction, the results showed that the former affects the latter, and in terms of intervening variables, both of these appeared to have a positive (+) effect on customer loyalty. Conclusions - This study suggests that family restaurants should look for strategies that focus on how to promote customer relationships. For example, restaurants could try birthday events or discount events to achieve this goal. Since the study ended up realizing relatively low levels of suitability and statistical significance, the path of the study changed. After all, in order to increase suitability and statistical significance, the study had to eliminate factors such as service quality and others and for this reason the study was unable to conduct the analysis as initially planned. In addition, the data samples of the research were mainly gathered from students, which made it hard to say that the analysis was carried out on samples from every different group. Future research should analyze the characteristics of each group of customers for factors affecting customer satisfaction and customer loyalty in the family restaurant chain.

• 융합보안논문지
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• 제22권5호
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• pp.49-59
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• 2022

자동차 분야의 사이버보안은 자동차 생애주기 중 핵심적인 요소로서 전 세계적으로 사이버보안 평가 기준이 강화되고 있다. 또한 자동차의 설계 및 생산을 수행하는 제조사만이 아니라 복잡한 컴포넌트와 다양한 부품으로 이루어진 자동차의 특성상 전체 공급망에 참여하는 기업들의 사이버보안 관리체계 구현 수준이 평가되고 관리되어야만 사이버보안의 안전성을 확보할 수 있다. 이에 본 연구에서는 자동차 사이버보안을 평가하는 대표적인 기준인 ISO/SAE 21434와 TISAX의 요구사항을 분석하여 총 7개 영역, 54개 사이버보안 관리체계를 평가할 수 있는 항목을 도출하였고 이를 국내/외 기업 보안담당자 및 유관 전문가 대상으로 진행한 설문조사를 통해 우선순위 및 업종에 따른 적합성, 타당성 검토를 거쳐서 6개 영역, 45개 평가 기준을 도출하여 최종 평가항목으로 제시하였다. 본 연구는 자동차 공급망에 참여하는 기업이 ISO/SAE 21434와 TISAX 전반의 통제 프로세스를 일률적으로 도입하기 전에 우선 적용하여 해당 기업의 현재 사이버보안 관리 수준을 평가할 수 있는 모델을 제시했다는 점에서 연구로서의 의의가 있다고 할 수 있다.

• 대한안전경영과학회지
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• 제6권1호
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• pp.157-172
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• 2004

The results of this study has been split into two components, On set of results addressed the strategy of developing a Agility for maintenance consumer. The other set of results addressed the strategy of illuminating the successful measurement and concepts formed during the maintenance problem solving process, especially in the context of the Logistics Information system by aggregation information space. This paper presented a classifiable elements of Agility & Measurement of logistics capability in the Korea market. These concepts are positioned in a framework to give a better understanding what the consequences are of the changing business environment. The developments towards more globalization which leads to centralization and mass individualization that has a tendency to go more in the decentralized solutions, seems to be in contradiction. we will focus a proposal of Logistics information system and demand management decisions that should be a prime concern of any profit maximizing firm, unready strategy of investment. and we will prove the facts that it could be a guiding company which has a ability of cooperation with entities through the founding of supply chain, On the conclusion, we will show the variation which influences for capacity entities and alternative proposal to define a element which influnce for a cause and effect basically.[5]

• Biomolecules & Therapeutics
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• 제21권2호
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• pp.126-131
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• 2013

Neuropathic pain is a chronic pain disorder caused by nervous system lesions as a direct consequence of a lesion or by disease of the portions of the nervous system that normally signal pain. The spinal nerve ligation (SNL) model in rats that reflect some components of clinical pain have played a crucial role in the understanding of neuropathic pain. To investigate the direct effects of gabapentin on differential gene expression in cultured dorsal root ganglion (DRG) cells of SNL model rats, we performed a differential display reverse transcription-polymerase chain reaction analysis with random priming approach using annealing control primer. Genes encoding metallothionein 1a, transforming growth factor-${\beta}1$ and palmitoyl-protein thioesterase-2 were up-regulated in gabapentin-treated DRG cells of SNL model rats. The functional roles of these differentially expressed genes were previously suggested as neuroprotective genes. Further study of these genes is expected to reveal potential targets of gabapentin.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.129.1-129.1
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• 2010

Since the commencement of the fuel cell business in 2007, POSCO POWER has been the major supplier of the MCFC (Molten Carbonate Fuel Cell), which is the most commercialized stationary fuel cell system in the world. With its quite, yet active movement, more than 20MW MCFC systems have been installed and are operating in Korea. While trying to localize the components and set up a firm supply chain in Korea to provide more reliable and cost-competitive products to its customers, POSCO POWER is also devoting itself to developing new MCFC application products. One such product is a back-up power system, in which a back-up algorithm is embedded to the present system so that the product can work as a back-up generator in case of grid failure. The technology to enhance load following capability of a stack module is also being developed with the back-up algorithm. Another example is a building application, the goal being to make the present Sub-MW product suitable for urban area. For this, downsizing and modularization are the main R&D scope. The project for developing ship service fuel cell for APU application will launch soon as well. In the project, a system which can operate in marine environment, and reforming technology for liquid logistic fuel will be developed.

• 디지털융복합연구
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• 제13권10호
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• pp.219-224
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• 2015

본 연구는 우리나라 가계저축률의 정규분포혼합을 추정한다. 2014년 마이크로데이터인 MDSS를 이용하였고 추정방법으로는 깁스알고리즘을 이용하였다. 실증분석결과의 주요내용은 다음과 같다. 첫째, 정규분포혼합을 추정하기 위한 방법으로 깁스알고리즘은 잘 작동하였다. 즉 주요 모수추정치는 모두 정상적 분포를 갖는 것으로 나타났다. 둘째 저축률 자료는 적어도 2개의 성분, 즉 저축률이 평균 0%인 성분과 평균 29.4%인 성분으로 이루어져 있는 것으로 보인다. 즉 우리나라의 가계는 고저축률 집단과 저저축률 집단으로 나누어질 수 있다는 뜻이다. 셋째 정규분포혼합모형 자체는 어떤 가계가 첫째 성분 또는 둘째 성분에 속하는가를 설명할 수 없다. 이에 본 연구는 추가적인 분석을 수행하였지만 소득수준과 가구주 연령은 이에 대한 설명력을 지니지 못하는 것으로 판단된다.

• Journal of Nutrition and Health
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• 제31권8호
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• pp.1217-1225
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• 1998

This study was conducted to investigate the effects of shellfish on lipid metabolism in rats fed high fat supplements. Male sprague-dawley rats weighting approximately 165g were fed a basal diet, a high fat diet, or a high fat diet plus shellfish for 4 weeks. The shellfishes on the were oyster, hard-shelled mussel, little neck clam, and march clam. Alfter 4 weeks high fat diet, supplementation of 20% lard significantly increased plasma. GOT, GPT, ${\gamma}$-GTP , and liver triglyceride (TG). Plasma GOT, GPT, ${\gamma}$-GTP , triglyceride, and total cholestrerol levels were significantly lower in shellfish groups than in basal and high-fat groups regardless of high-fat supplementation (p<0.05). The total lipid and cholesterol content in liver showed similar results(p<0.05). There were no differences in glucose, HDL-cholesterol in plasma and total cholesterol and total lipid in liver between basal and high-fat supplemented diets. Liong chain fatty acids, specific components of shellfishes group, were exclusively higher than in basal and high-fat diets, and were most well-reflected in liver and plasma. From the above results, the hypolipidemic effects of shellfish were detected in the process of inducing hyperlipidemia by high-fat supplement.