• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.289-292
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• 2008

Highly over-expanded nozzle of the rocket engines will be excited by non-axial forces due to flow separation at sea level operations. Since rocket engines are designed to produce axial thrust to power the vehicle, non-axial static and/or dynamic forces are not desirable. Several engine failures were attributed to the side loads. Present work investigate the unsteady flow in an over-expanded rocket nozzle in order to estimate side load during a shutdown/starting. Numerical computations has been carried out with density based solver on multi-block structured grid. Present solver is explicit in time and unsteady time step is calculated using dual time step approach. AUSMDV is considered as a numerical scheme for the flux calculations. One equation Spalart-Allmaras turbulence model is selected. Results presented here is for two nozzle pressure ratio i.e. 100 and 20. At 100 NPR, restricted shock separation (RSS) pattern is observed while, 20 NPR shows free shock separation (FSS) pattern. Side load is observed during the transition of separation pattern at different NPR.

• 지식경영연구
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• 제22권1호
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• pp.85-103
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• 2021

최근 코로나 19의 세계적 대유행 이후로 비즈니스 업무환경이 스마트워크로 급격하게 변하고 있다. 스마트워크는 기본적으로 언제 어디서나 일을 할 수 있는 시스템을 근간으로 하고 있다. 스마트워크가 성공하기 위해서는 이러한 시스템의 구축과 운영 문제가 중요할 뿐만 아니라, 스마트워크 도입이 미치는 조직문화에의 영향을 연구하는 것도 중요하다. 본 연구에서는 한국의 레저 서비스 대기업인 H사에서 경영상 강조하고 있는 조직 문화의 일곱 가지 차원 - 전략적 혁신성, 조직 유연성, 공정한 인사관리, 합리적 의사결정, 조직 활력, 신뢰 협력, 리더십 - 에 있어서 스마트워크 전후로 어떤 변화가 있는지 설문과 인터뷰를 통하여 조사하였다. 조사결과 전략적 혁신성, 조직 유연성, 조직 활력, 신뢰 협력의 네 가지 차원에서는 직원들의 평가가 통계적으로 낮아진 것으로 나타났고, 공정한 인사관리, 합리적 의사결정, 리더십의 측면에서는 큰 변화가 없는 것으로 나타났다. 도입초기 단기적 현상일수도 있어 앞으로의 변화도 관찰할 필요가 있지만, 기업 관점에서 궁극적으로 유연한 업무 환경의 변화를 추구하는데 있어서 직원들로 하여금 전략적 혁신성, 조직 유연성, 조직 활력, 신뢰 협력과 같이 경영상 중요한 조직 문화의 측면에서 적극적으로 준비하고 대응하는 것이 필요함을 시사한다. 조직 활력이 상대적으로 낮아지고, 조직구성원간 신뢰 소통과 협력은 감소하는 것은 굉장히 부정적 변화로서 적극적 관리가 필요하다. 이어진 인터뷰에서는 스마트워크 도입의 성공적 정착을 위해서는 리더십의 역할이 중요하게 나타나고 있어, 향후 일하는 방식의 변화에 따라 경영진 리더십의 역할이 더욱 강조될 것이라는 것을 시사하였다.

• 전자공학회논문지C
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• 제36C권8호
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• pp.22-34
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• 1999

본 논문에서는 내장된 이중-포트 메모리를 위한 효율적인 테스트 알고리듬을 제안하였다. 제안된 테스트 알고리듬은 기존의 멀티-포트 메모리 테스트 알고리듬들보다 훨씬 빠르게 이중-포트 메모리를 테스트할 수 있으며, 고착 고장, 천이 고장 및 결합 고장을 완벽하게 검출할 수 있다. 또한, 본 연구에서는 제안된 알고리듬을 수행할 수 있는 BIST 회로를 Verilog-HDL을 이용하여 설계하고 시뮬레이션과 합성을 수행하였으며, BIST로 구현된 제안된 테스트 알고리듬의 높은 효율성을 다양한 크기의 내장 메모리에 대한 실험을 통하여 확인할 수 있었다.

• Carbon letters
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• 제28권
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• pp.55-59
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• 2018

Transition-metal-embedded carbon nanotubes (CNTs) have been accepted as a novel type of sensing material due to the combined advantage of the transition metal, which possesses good catalytic behavior for gas interaction, and CNTs, with large effective surface areas that present good adsorption ability towards gas molecules. In this work, we simulate the adsorption of $O_2$ and $O_3$ onto Rh-doped CNT in an effort to understand the adsorbing behavior of such a surface. Results indicate that the proposed material presents good adsorbing ability and capacities for these two gases, especially $O_3$ molecules, as a result of the relatively large conductivity changes. The frontier molecular orbital theory reveals that the conductivity of Rh-CNT would undergo a decrease after the adsorption of two such oxidizing gases due to the lower electron activity and density of this media. Our calculations are meaningful as they can supply experimentalists with potential sensing material prospects with which to exploit chemical sensors.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.718-725
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• 2003

The present study addresses the distortion of the compression wave reflected from an open end of a shock tube. An experiment is carried out using the simple shock tube with an open end Computational work is also performed to represent the experimented flows. The second-order Total Variation Diminishing scheme is employed to numerically solve the unsteady, axisy-mmetric, inviscid, compressible governing equations. Both the experimented and predicted results are in good agreement. The generation and development mechanisms of the compression wave, which Is reflected from the open end of the shock tube, are obtained in detail from the present computations. The effect of size of the baffle plate at the open-end that causes the reflection of the incident expansion wave is found negligible. A good correlation is obtained for transition of the reflected compression wave to a shock wave inside the tube. The present data show that for a given wave length of the incident expansion wave the transition of the reflected compression wave to a shock wave can be predicted with good accuracy.

• 경영정보학연구
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• 제23권4호
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• pp.23-43
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• 2021

최근 비대면 사회로의 전환으로 많은 조직이 빠르게 스마트워크 환경을 조성하고 있다. 스마트워크의 도입은 단순히 ICT 시스템 또는 솔루션 도입이 아닌 기술적 진보에 맞춰 일하는 방식이나 직무 형태의 다양한 변화를 초래한다. 그러나 스마트워크 관련 기존 연구들은 기술수용관점에서 스마트워크 도입으로 생산성 및 효율성이 향상된다는 연구가 대부분으로 기업의 ICT 시스템이 도입되었을 때 구성원들이 느끼는 혁신저항의 문제와 조직의 관리 통제에 대한 현실적인 문제에 대한 논의는 부족하다. 본 연구는 스마트워크 도입에 대한 혁신요인과 혁신저항에서 구성원들에 대한 조직통제 방법의 조절효과를 실증분석하고 혁신저항의 관점에서 조직의 혁신이 들어왔을 때 구성원들이 저항하는 구조적인 특징을 이직의도로 확장하여 프로세스에 대한 개념적 모델과 가설을 제안하였다. 실증 분석 결과, 스마트워크 도입 관련 ICT 기술의 기업 내부 도입에 대하여 상대적 이점, 자기효능감의 수준이 높을수록 혁신저항의 수준이 낮아지고, 이용복잡성이 높을수록 혁신저항의 수준이 높아지는 것으로 나타났다. 또한 사용자들의 행동통제를 하였을 때 혁신저항이 증가하는 것으로 나타났다. 본 연구의 결과는 사례 분석을 통해 향후 스마트워크 도입에 대한 고려 사항을 제시하여 신규 도입을 위한 경영개선에 기여하는 바를 제공하고자 한다.

• 대한화학회지
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• 제57권6호
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• pp.726-730
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• 2013

Complexes synthesized by reacting alkyl and aryl phosphines with different transition metals are of great interest due to their catalytic properties. Many of the phosphine complexes are soluble in polar solvents as a result they find applications in homogeneous catalysis. In our present work we report, four transition metal complexes of Ni(II), Pd(II), Pt(II) and Ru(II) with an asymmetrical ditertiaryphosphine ligand. The synthesized ligand bears a less electronegative substituent such as methyl group on the aromatic nucleus hence makes it a strong ${\sigma}$-donor to form stable complexes and thus could effectively used in catalytic reactions. The complexes have been completely characterized by elemental analyses, FTIR, $^1HNMR$, $^{31}PNMR$ and FAB Mass Spectrometry methods. Based on the spectroscopic evidences it has been confirmed that Ni(II), Pd(II) and Pt(II) complexes with the ditertiaryphosphine ligand showed cis whereas the Ru(II) complex showed trans geometry in their molecular structure.

• 한국의류산업학회지
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• 제11권2호
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• pp.231-241
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• 2009

Embroidery is one of the oldest methods of textiles surface decoration. The masterpiece "Tapisserie de Bayeux," is one of the earliest Medieval embroideries. Embroidery was popular on a broad scale with introduction of what was called Opus Anglicanum("English work") in the 13th century. France had been producing sophisticated embroideries since the 16th century. England was the country producing the greatest quantity of embroideries of the best quality in the 17th century. Until the 17th century, the Church was the most important patron of needlework. Then a shift in emphasis occurred towards the domestic embroidery. English 17th century domestic embroidery reached a high point of technical brilliance and charm. In France, embroidery was produced on hangings as well as costume. 18th century interest in embellishing the domestic environment, embroideries became much more finely detailed than those of the 17th century with the use of finer wool and silk threads. French silk were the finest in the world, and their embroidery was arguably equally fine both in furnishing textiles and on costumes. "Art Needlework" was the major movement in embroidery in the late 19th century. The Royal School of Needlework was founded in 1872, followed by similar institutions around Britan. Splendid fashion embroidery of French haut-couture that was represented to Lesage atelier in 20th century.

• 한국전산유체공학회지
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• 제17권3호
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• pp.53-58
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• 2012

Steady flow simulations through a high pressure turbine guide vanes were carried out. The main objective of the present work is to study the performance of turbulence models on the steady flow prediction from aerodynamic and aerothermal points of view. Three turbulence models were compared, namely SST, k-${\omega}$ and ${\omega}$-Reynolds stress models. The laminar results were also compared. The comparison was done with emphasis on the isentropic Mach number and heat transfer coefficient along the blade, and total pressure loss in the wake region. The calculated isentropic Mach number showed reasonable agreement with experimental data along the blade surface for all three turbulent models. For the total pressure loss in the wake region, ${\omega}$-Reynolds stress model showed the best agreement with the experimental data. However, unless using an appropriate transition model, the heat transfer coefficients of all three turbulent models showed poor agreement with experimental data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.493-493
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• 2000

Multi-valued decision making for transitional stochastic events was newly derived based on conditional probability of database. The two values (on-off) decision making method without transition had been proposed by one of the author in a previous work for a purpose of realizing human on-off decision making. The current method is an extension of the previous on-off decision making. By combining the conditional probability and the transitional probability, the closed form of the algorithm for the multi-valued transitional decision making was derived. The proposed multi-valued decision making was successfully applied to the determination of the five levels of the vigilance of a subject during the EEG recording; awake stage, drowsy stage and sleeping stages (stage 1, stage 2/3, REM (rapid eye movement)). The method for determining the vigilance level can be directly usable for the two purposes; selection of awake EEG segments for automatic EEG interpretation, and determination of sleep stages through sleep EEG. The proposed multi-valued decision making with a mathematical background of the probability can be applicable widely, in industries and in medical fields for purposes of the multi-valued decision making.