• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.402-406
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• 2013

In this study, a pitch for melt-electrospinning was prepared from naphtha cracking bottom (NCB) oil by the modification with heat treatment. The softening point and property of the modified pitch was influenced by modification conditions such as nitrogen flow rate, heat treatment temperature, and reaction time. Among these, the heat treatment temperature had a very strong influence on the distribution of molecular weight and softening point of the pitch. The C/H mole ratio and average molecular weight increased with increasing the heat treatment temperature due the decomposition and cyclization reaction of surface-functional groups. In addition, the values of benzene insoluble and quinoline insoluble also tends to decrease, and the width of molecular weight distribution seems to get more narrow. The carbon fiber with a diameter of $4.8{\mu}m$ was prepared from a modified pitch at the softening point of $155^{\circ}C$ by melt-electrospinning. It is believed that the melt-electro spinning method is much more convenient to get the thinner fiber than the conventional melt spinning method.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.457-462
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• 2009

In this paper we suggest optimal positioning algorithm for DER(distributed energy resource)s near ocean side by using Newton-Rhapson load flow calculation. By installing DERs within urban area, electric power can be effectively transmitted to each loads without constructing additional large scale power stations and transmission lines. Therefore, DERs have attracted worldwide attention as urban area energy sources. However, there are quite a few studies for estimation of power loss due to DERs' location change within urban area Hence, in this study, an optimal positioning scheme for DERs is proposed in order to minimizing electrical power loss.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.405-412
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• 2006

It is well known that shotcrete is the most important support member for the construction of large underground spaces. Generally, the strength of the field shotcrete is heavily dependent on the field mixing and spraying conditions so that it is different from the strength of the shotcrete mixed in laboratories. As a support member, the early strength of shotcrete unlike concrete is very important to the initial stabilization of the underground spaces. Therefore, the field methods to efficiently test the early strength of shotcrete have been highly required. This paper aimed to verify the pneumatic pin penetration test and the point load test for measuring the early strength of the field shotcrete. As a result of the experiments through a series of uniaxial compression, pin penetration, and point load tests for the range of the early shotcrete strength, two equations to estimate reliably the uniaxial compressive strength by the pin penetration and the point load tests were acquired.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.345-352
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• 2007

Two-dimensional (2D) MT surveys near the Century mine in Australia have been performed with very far remote reference in Esashi, Japan (RR_ESS) as well as Gregory Downs (RR_GREG), which are roughly 6,400 km and 80 km apart from the survey area, respectively. Good quality of MT data could be obtained by remote reference processing with RR_GREG, while the coherency of magnetic fields between field sites and RR_ESS was not sufficient to be used as remote data. Both 2D and 3D inversion of 2D profile data represented the general geological structure beneath the survey area. The main target of the survey, Termite Range Fault, appeared as a boundary between a conductive block to the north and a resistive block to the south in the reconstructed resistivity section, and is inclined slightly to the north-east direction.

• Proceedings of the Korea Database Society Conference
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• 1999.10a
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• pp.143-152
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• 1999

세계 소프트웨어 시장의 급속한 성장과 함께 선진국들은 자국에 유리한 소프트웨어 품질표준을 만들어 이를 국제 표준에 반영하고, 외국 소프트웨어에 대한 진입 규제의 수단으로 활용하고 있다. 또한 전자상거래의 발달로 인해 디지털 상품인 소프트웨어는 전자상거래를 통한 거래가 쉬운 이점을 가지고 있는 상황에서 아직 우리나라에서는 패키지 소프트웨어에 관한 품질모형 개발에 관한 연구가 다소 미흡한 실정이다. 본 연구에서는 기존 국내외 소프트웨어 품질평가모형을 도출하고, 그 평가모형을 바탕으로 전자상거래에서 활용 가능한 패키지 소프트웨어만을 대상으로 품질평가모형을 개발하였다. 그리고 평가모형을 적용하기에 앞서 소프트웨어 개발 업체를 대상으로 설문조사를 실시하여 품질평가모형에 대한 실증분석을 하였다. 실증분석은 현재 개발업체가 취급하고 있는 제품에 대한 종류와 개발업체에서 평가받기를 원하는 제품의 종류, 그리고 평가대상이 될 수 있는 패키지 소프트웨어 제품의 경쟁력 수준과 관련하여 선진국의 제품과 비교하여 5점 척도로 조사하였다. 그리고 소프트웨어 개발자 입장에서 품질평가 항목별로 중요도를 조사하였으며 분석결과를 토대로 품질평가모형의 적용 대상을 선정하였다. 적용대상 제품은 모두 14개로 각각의 제품들을 게임, OA, 통신, ERP, 4GL, OS 소프트웨어로 분류하고 제품에 대한 평가는 개발자(개발경력 3년 이상)와 일반사용자로 분류하여 평가를 실시하였다. 그리고 각 제품분야별로 평가항목에 대한 가중치를 전문가 집단에 의뢰하여 적용하였다. 평가방법은 각각의 제품에 대한 평가점수를 1점부터 5점까지 나누어 평가결과를 평균값으로 나타냈으며, 평가결과에 대해 여러 가지 방법으로 분석하였다. 첫째, 동종제품간 평가분석을 통하여 각각의 제품을 비교하였으며, 둘째 소프트웨어 종류별 평가로 제품을 응용소프트웨어, 응용개발도구, 시스템 소프트웨어로 분류하여 평균값으로 비교하였다. 셋째, 국내외 제품별 평가분석으로 전체 제품을 국내제품과 국외제품으로 분류하여 비교하였으며, 마지막으로 총괄분석을 통해 가중치를 적용하여 전 제품의 점수를 비교하였다. 여기에서는 각 제품의 평균점수에 대한 차이를 95%의 유의수준으로 T-Test를 실시하였다.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.181-185
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• 2024

The purpose of this research is to investigate how purchase cycle of a product and bundle frame influence consumers' responses to the bundle promotion. In order to test hypotheses of this study, we conducted an experimental study that was a 2(Purchase cyle: Long vs. Short) X 2(Bundle frame: 1+1 vs. Buy2 and 50% off) between-subjects design. The reseults of this study showed the interaction effects of purchase cycle of product and bundle frame on perceived level of discount and product attitude. Based on the results, we provide theoretical implcations to extent the existing research regarding bundling promotion. Moreover, the results of this study suggest some practical implications and a new aspect about bunle promotions.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.5
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• pp.125-137
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• 2024

This study aims to analyze the relationship between environmental management practices and environmental operational performance, and empirically verify the moderating effect of cost structure uncertainty in this relationship. To test the hypotheses proposed in this study, a moderation analysis using hierarchical regression was conducted. Results reveal an inverted U-shaped relationship between environmental practices and operational performance, moderated by cost structure uncertainty. While environmental practices initially lead to operational performance improvements, benefits diminish beyond a certain threshold. Higher cost uncertainty lowers the optimal level of environmental practices. These findings provide important implications for corporate environmental strategy formulation. Rather than indiscriminately expanding environmental practices, firms should identify optimal levels and adopt strategic approaches considering cost uncertainty.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.226-233
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• 2008

The nucleation and evolution process of Ge nano-islands on Si(001) surfaces grown by chemical vapor deposition have been explored using atomic force microscopy (AFM). The Ge nano-islands are grown by exposing the substrates to a mixture of gasses GeH4 and H2 at pressure of 0.1-0.5Torr and temperatures of $600-650^{\circ}C$. The effect of growth conditions such as temperature, Ge thickness, annealing time on the shape, size, number density, and surface distribution was investigated. For Ge deposition greater than ${\sim}5$ monolayer (ML) with a growth rate of ${\sim}0.1ML/sec$ at $600^{\circ}C$, we observed island nucleation on the surface indicating the transition from strained layer to island structure. Further deposition of Ge led to shape transition from initial pyramid and hut to dome and superdome structure. The lateral average size of the islands increased from ${\sim}20nm$ to ${\sim}310nm$ while the number density decreased from $4{\times}10^{18}$ to $5{\times}10^8cm^{-2}$ during the shape transition process. In contrast, for the samples grown at a relatively higher temperature of $650^{\circ}C$ the morphology of the islands showed that the dome shape is dominant over the pyramid shape. The further deposition of Ge led to transition from the dome to the superdome shape. The evolution of shape, size, and surface distribution is related to energy minimization of the islands and surface diffusion of Ge adatoms. In particular, we found that the initially nucleated islands did not grow through long-range interaction between whole islands on the surface but via local interaction between the neighbor islands by investigation of the inter-islands distance.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.13-18
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• 2013

This study was conducted to monitor residual pesticides in ginseng and balloon flower roots and to assess their risk to human health. All of 112 samples consisted of ginseng and balloon roots were purchased from traditional domestic markets and supermarkets in nine provinces of Korea in 2012. Multi-residue analysis of 122 pesticides was conducted and the analysis was performed by gas chromatography-electron capture detector, gas chromatography- nitrogen/phosphorus detector, and high-performance liquid chromatography. Seven pesticides were detected in 12 root samples and the detection rate was 10.7%. The detected twelve root samples were 10 ginseng root samples and 2 balloon root samples. Pesticides detected in root samples were procymidone, kresoxim-methyl, endosulfan, cypermethrin, tralomethrin, tetraconazole and chlorfluazuron. Among them, two pesticides as tetraconazole in a balloon flower root and cypermethrin in a ginseng root exceeded the recommended maximum residue limit set by Korea Food and Drug Administration. Five pesticides detected from 10 root samples were identified as unregistered pesticides in Korea. In order to do risk assessment with Korean medicinal plant consumption, estimated daily intake of residual pesticides were determined and compared to acceptable daily intake, referring to %ADI values. The range of %ADI values was from 0.006% to 0.333%. Taken together, it demonstrates the pesticides found in the two root samples were below the safety margin, indicating no effect on human health.

• Korean Journal of Environmental Agriculture
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• v.32 no.2
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• pp.142-147
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• 2013

BACKGROUND: This study was conducted to monitor residual pesticides in domestic agricultural products and to assess their risk to human health. METHODS AND RESULTS: 123 samples containing both general and environment-friendly certified agricultural products were purchased from traditional domestic markets and supermarkets in six provinces of Korea. Multiresidue analyses of one hundred twenty-two pesticides except for herbicides were performed with gas chromatography-electron capture detector, gas chromatography-nitrogen/phosphorus detector, and high-performance liquid chromatography. Sixteen pesticides were detected in 45 agricultural product samples, which were 38 general, 6 low pesticide and 1 of GAP agricultural product samples and the detection rate was 33.6%. Pesticides detected in agricultural product samples were cypermethrin, lufenuron, fenvalerate, bifenthrin, chlorfenapyr and iprodione. Residual concentration of 18 samples were exceeded the recommended maximum residue limit set by Ministry of Food and Drug Safety and two kinds of unregistered pesticides in korea were also detected in two samples. CONCLUSION(S): In order to do risk assessment by agricultural products consumption, estimated daily intake of residual pesticides were determined and compared to acceptable daily intake, referring to %ADI values. The range of %ADI values was from 0.038% to 2.748%. Taken together, it demonstrates the pesticides found in agricultural products samples were below the safety margin, indicating no effect on human health.