• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1595-1603
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• 2002

In this paper we have presented the results of diffusion behavior of model systems for eight liquid n-alkanes ($C_{12}$-$C_{44}$) in a canonical (NVT) ensemble at several temperatures using molecular dynamics simulations. For these n-alkanes of small chain length n, the chains are clearly <$R_{ee}^2$>/6<$R_g^2$>>1 and non-Gaussian. This result implies that the liquid n-alkanes over the whole temperatures considered are far away from the Rouse regime, though the ratio becomes close to the unity as n increases. Calculated self-diffusion constants $D_{self}$ are comparable with experimental results and the Arrhenius plot of self-diffusion constants versus inverse temperature shows a different temperature dependence of diffusion on the chain length. The global rotational motion of n-alkanes is examined by characterizing the orientation relaxation of the end-to-end vector and it is found that the ratio ${\tau}1/{\tau}2$ is less than 3, the value expected for a isotropically diffusive rotational process. The friction constants ${\xi}$of the whole molecules of n-alkanes are calculated directly from the force auto-correlation (FAC) functions and compared with the monomeric friction constants ${\xi}_D$ extracted from $D_{self}$. Both the friction constants give a correct qualitative trends: decrease with increasing temperature and increase with increasing chain length. The friction constant calculated from the FAC's decreases very slowly with increasing temperature, while the monomeric friction constant varies rapidly with temperature. By considering the orientation relaxation of local vectors and diffusion of each site, it is found that rotational and translational diffusions of the ends are faster than those of the center.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.332-332
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• 2017

Rice ratooning is the cultural practices to produce easily second rice from the stubble left behind after the main-crop harvest. The main advantage of rice ratooning is that in areas where rice is the main crop, double crop of rice can be grown for additional returns. Three early ripened rice cultivars were tested for estimation their milled rice quality and starch characteristics from main and ratoon rice. The main crop was harvested at mass maturity, after which the tillers were mowed to stubbles of about 10 cm tall. And then it left without any further input until the ratooned plant was ready for harvest. Highly significant variations were detected in the milled rice quality between main and ratoon rice. Protein and amylose contents of ratoon rice were more increased than those of main rice. The Toyo value (gloss) of cooked rice of ratoon crop was measured also higher than that of main crop. It resulted from higher air temperature during grain ripening compared with that of ratoon crop. The mean temperature during ripened period of ratoon rice was favorable for optimal maturation for early ripened rice cultivars. Normalized chromatograms of branch chain length distribution of amylopectin are demonstrated a distinct difference between main and ratoon rice flour. Ratoon rice had higher amount of short chains than that of main crop rice starches. Microscopic examination of rice flours with scanning electron microscopy shows starch granule shapes affected by the cropping types, main and ratoon rice. It showed significant differences among rice starch granule shapes and in granule size between main and ratoon rice. Starch of ratoon rice had more neat and smaller granules than that of main rice.

• 정보처리학회논문지D
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• 제10D권1호
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• pp.161-166
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• 2003

제품을 생산하고 공급하는데 소요되는 주문리드타임과 달리 주문이 처리되는데 소요되는데 지연되는 것을 정보리드타임이라고 하는데, 이는 공급체인에서 개별기업들이 수요예측의 변동폭을 높이게 되며 이것이 바로 비용 상승요인으로 작용하게 된다. 본 논문에서는 직렬형 가치사슬에서 정보리드타임이 공급체인 시스템에 주는 영향을 알아본다. 특별히, MIT 시뮬레이션 모형을 동해서 실험을 수행하며, 아래와 같은 두 가지의 이슈를 다룬다. 첫째는 비용-이익 관점에서 물류 리드타임보다 정보리드타임의 개선이 효과적인가\ulcorner 둘째는 정보리드타임이 고객에게 보다 인접한 기업(downstream)이 고객하고 떨어져 있는 기업(upstream)보다 비용을 크게 상승시키고 있는지에 대한 물음이다. 사례 분석에서는 공급체인상의 개변기업들이 갖는 정보리드타임의 중요성을 지적하고, 개별기업간의 정보리드타임의 차이 분석을 통해서 고객의 수요와 요구를 직접 받는 기업에서 정보리드타임의 중요성이 큼을 인증하고 있다.

• 융합보안논문지
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• 제20권3호
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• pp.89-97
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• 2020

산업기술 보안 이슈는 대내외적으로 급격한 변화를 겪고 있다. 미국 등 선진국은 글로벌 가치사슬 및 해외자본 이동과 갈등을 빚으면서도 자국의 핵심 기술 보호를 위한 대응전략을 수립하고 있으며, 국내 또한 중장기 산업경쟁력 속에서 산업안보이슈를 접근하고 있다. 본 연구에서는 국내 산업보안 관련 이해관계자들을 대상으로 산업보안 생태계 정책인식 조사를 통해 주요 이슈를 도출하였다. 조사결과, 이해관계자 모두 산업보안의 중요성에 대해 인식하나 아직까지 국가전체 보안관리 역량은 낮다고 인식하고 있으며, 국가핵심기술은 국가에서 보다 책임을 지고 관리할 필요성이 있음을 제기하였다. 3라운드에 걸친 종합 델파이 조사를 기반으로 '산업보안 컨트롤타워 중심 시스템 체계화', '보안전문기업 기술력 강화 및 보안인력 양성', '인력 및 자본을 통한 기술유출 방지제도 개선', '연구개발 과정에서의 연구보안 및 선제적 기술보호 강화'를 정책개선 과제로 제시하였다. 본 연구가 산업보안 현장의 수요를 반영한 증거 기반 연구로서 관련 정책수립의 기초가 될 수 있기를 기대한다.

• 한국재료학회지
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• 제30권1호
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• pp.38-43
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• 2020

Sand casting 3D printing uses a binder jetting method to produce a mold having complicated shape by spraying a binder on sand coated with activator. Appropriate heat treatment process in sand mold fabrication can increase the degree of polymerization to improve flexural strength. However, long heat treatment of over 24 hours decreases flexural strength and reliability due to chemical bond decomposition through thermal degradation. The main role of the activator is to control the reaction rate between the polymer chains. As a result, when the activator composition is increased from 0.15 wt% to 0.25 wt%, the flexural strength is increased by 218 N/㎠. However, excess activator (0.40 wt%) has been shown to decrease reliability without increasing flexural strength. The main role of the binder is to control the flexural strength of the specimen. As the binder composition is increased from 2.00 wt% to 4.00 wt%, the flexural strength increases to about 255 N/㎠, indicating the maximum flexural strength increase. Finally, the reliability of the flexural strength of the fabricated specimens is evaluated by a Weibull plot. Weibull modulus calculations are used to evaluate the flexural strength reliability of the specimens, and maximum reliability value of 11.7 is obtained at 0.20 wt% activator composition. Therefore, it is confirmed that this composition has maximum flexural strength reliability.

• 산업경영시스템학회지
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• 제43권1호
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• pp.110-122
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• 2020

Many companies make considerable efforts in implementing supply chain management systems to increase their competitiveness. In particular, there are significant investments in their ICT (Information and Communication Technology) and supply chain. However, considerable diversity exists in how well firms have been able to assimilate ICT and leverage the business value of it. In addition, studies on supply chains, particularly Real Time Enterprise (RTE) competence, which is cited for rapid information sharing and dynamic capabilities for each role in the supply chain, are insufficient. The purpose of this paper is to explore and evaluate effect of ICT utilization capabilities, including 'ICT internal cooperative capabilities' and 'ICT operational flexibility capabilities', on RTE capabilities (flexibility, visibility and prediction) and supply chain performance. To validate the research model proposed in the study, survey was conducted on companies using ICT along the supply chain of manufacturing industries. 216 data were used, SPSS and AMOS were used for the analysis methods. Study results showed that ICT internal collaboration capabilities affect agility, one of RTE capabilities, but not visibility and prediction, and ICT operational flexibility capabilities have affected all three RTE capacities. And, RTE capabilities had a huge impact on supply chain performance as expected. In this paper, it has been found that the ICT capabilities in manufacturing are an important factor in improving RTE capabilities that are important in the supply chain and improving the performance of the supply chain.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3052-3058
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• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• 서비스연구
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• 제1권1호
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• pp.123-148
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• 2011

서비스 비즈니스는 그 분야가 프로세스나 상품 유형 등에 있어서 매우 다양하다. 따라서 상호 의사소통이나 경험 학습의 공유가 중요한데도 불구하고, 이 분야에서는 그동안 전통적으로 학술적인 그리고 체계적인 연구가 활성화되지 못했다. 그러나 최근에 각종 서비스 비즈니스에 대한 수요와 공급이 급격히 증가하고, 이 분야에 특히 서비스사이언스라는 매크로 이슈가 제시되는 등 서비스에 대한 과학적이고 체계적인 접근의 중요성이 높아지고 있다. 본 연구에서는 특히 서비스 혁신 관점에서 서비스 분야에 대한 연구 영역과 관련된 연구 내용들에 대해서 논의하고, 향후 시도되어야 할 서비스 분야의 연구 주제들을 주로 Ostrom 등의 최근 연구에 기반하여 제안하였다. 서비스 혁신 관련 이슈는 서비스 기획, 개발, 그리고 실행의 3개 영역으로 구분될 수 있으며, 본 연구에서는 기획영역에서 서비스화 및 기존 서비스의 성장, 전환 서비스를 통한 웰빙 기여, 서비스 문화의 창조와 유지, 개발 영역에서 서비스 혁신의 유도, 서비스 혁신의 향상, 서비스 네트워크와 가치체인의 최적화 등 총 6개 주제별로 정리하였으며, 각 분야별로 중요한 연구 실적, 향후 연구 동향, 연구 사례를 소개하였으며, 앞으로 연구가 활성화되어야 이슈 등을 제시하였다.

• 경영정보학연구
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• 제6권2호
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• pp.227-242
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• 2004

디지털 경제의 확산으로 오늘날 경영환경은 개별기업간 경쟁체계에서 공급체인간의 경쟁체계로 급속도로 변화되고 있다. 이와 같은 환경변화에 대응하기 위한 도구로서 기업간의 협업체계 구현을 위한 e-파트너링의 필요성이 대두되고 있다. e-파트너링이란 가치사슬(Value Chain) 전과정에서 소수의 정예화된 파트너와 네트워크를 형성하여 새로운 사업모델을 구축하고 공동성장이 가능한 사업생태시스템(Business Ecosystem)으로 발전시켜나가는 과정이라고 정의할 수 있다. 본 연구에서는 대표적인 기간산업인 조선산업과 철강산업을 대상으로 e-파트너링 추진방안을 도출하기 위하여 e-파트너링의 수준 모형을 재정립하여 연구대상에 적합한 수준모형을 설정하고 이를 실질적으로 구현하기 위한 달성방안으로 일자별?계열별 주문 공급체계, 쌍방향 커뮤니케이션 시스템, 운송수단을 포함한 물류 인프라 개선안을 제시하였다. 제시된 달성방안을 추진한 결과, 정량적으로 납기단축 및 재고수준 감소 효과를 가져왔으며 정성적으로도 상호간의 업무커뮤니케이션이 향상되는 효과가 나타났다.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1861-1866
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• 2012

The new semiconducting copolymers with 4,4-dialkyl-$4H$-cyclopenta[2,1-$b$:3,4-$b^{\prime}$]dithiophene and 2,2-dimethyl-$2H$-benzimidazole units were synthesized. The fused aromatic rings, such as cyclopentadithiophene (CPDT) unit, can make the polymer backbone more rigid and coplanar, which induces long conjugation length, narrow band gap, and strong intermolecular ${\pi}-{\pi}$ interaction. The stacking ability was controlled through attaching of linear or branched alkyl side chains. The spectra of PEHCPDTMBI and PHCPDTMBI in the solid films show absorption bands with maximum peaks at 401, 759 and 407, 768 nm, and the absorption onsets at 925 and 954 nm, corresponding to band gaps of 1.34 and 1.30 eV, respectively. The devices comprising PHCPDTMBI with $TiO_X$ showed a $V_{OC}$ of 0.39 V, a $J_{SC}$ of 1.14 $mA/cm^2$, and a $FF$ of 0.34, giving a power conversion efficiency of 0.15%. The PHCPDTMBI with linear alkyl chain on CPDT shows good solubility in organic solvent with higher PCE value than that of PEHCPDTMBI.