• 공업화학
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• 제29권1호
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• pp.37-42
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• 2018

폴리프로필렌(PP)과 케나프섬유(KF) 펠트의 상용성 개선을 위해 3종류의 실란 커플링제 1 wt%를 PP/KF 펠트에 처리하여 PP/KF와 PP/KF/폴리우레탄(PU) 펠트 복합체를 제조하였다. KF에 실란 커플링제 결합여부 확인을 위해 Si-O-Si와 Si-O-C 작용기를 적외선분광기(FT-IR)와 X선 광전자분광분석기(XPS)를 이용하여 측정하였다. 열적 특성분석을 위해 시차주사열용량분석기와 열중량분석기를 이용하였으며, 실란 커플링제가 처리된 PP/KF 복합체의 열안정성이 증가하는 결과를 보여주었다. PP/KF와 PP/KF/PU 복합체의 인장, 굴곡 그리고 충격특성을 분석한 결과 기계적 특성의 개선효과는 (3-Aminopropyl)triethoxysilane (APS) 1-2 wt%에서 가장 우수하였다. 이와 같은 기계적물성의 개선은 실란 작용기가 천연섬유와 결합하여 PP와 KF의 상용성을 향상시킨 결과로 해석할 수 있고, 인장시험 후 파단면의 SEM 결과를 통해 확인하였다.

• 한국약용작물학회지
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• 제21권1호
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• pp.7-19
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• 2013

This study was carried out to select new pelleting binder and material for seeds from Fraxinus rhynchophylla Hance and Alnus sibirica Fisch. ex Turcz. The optimum treatments of the various concentrations and species of priming agents to improve seed germination of both woody medicinal plants were also estimated. Germinability was increased when the seeds of Fraxinus rhynchophylla Hance was soaked in -1.0 MPa of PEG6000 solution at $15^{\circ}C$ for 4 days significantly, the optimum treatment for improving germination of Alnus sibirica Fisch. ex Turcz was observed when the tested seeds was soaked in 100 mM of KCl at $15^{\circ}C$ for 4 days. The influence of physical and chemical properties of pelleting solid materials, the mixture of gypsum, diatomaceous earth, dalma ceramic and vermicuolite (6:1:1:1 ratio) were found as the best pelleting materials for Fraxinus rhynchophylla Hance and Alnus sibirica Fisch. ex Turcz. seeds. To satisfy the requirements of absorption and compatibility for multi-layer seed pelleting, SGPA (Starch-grafted cross-linked polyacrylates) hydrogel was prepared using starch, acrylonitrile, ceric ammonium nitrate, nitric acid, methyl alcohol and potassium hydroxide. The resulting SGPA hydrogel showed high water absorption but not plant compatibility. It suggested that seed pelleting using pelleting materials and SGPA hydrogel (multi-layer coating) after priming agent treatment is to increase germinability and seedling growth and it can reduced irrigation labours and can also save seed.

• 한국정보과학회논문지:시스템및이론
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• 제33권1_2호
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• pp.79-91
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• 2006

지능형 디스크는 이전에 호스트 프로세서에서 수행되던 입출력 관련 연산 작업을 디스크 상에서 수행함으로써 전체적인 입출력 성능을 향상시킬 수 있다. 하지만, 현 시점에서 입출력 시스템이 가지는 한계와 하위 호환성 문제로 인하여 지능형 디스크를 직접적으로 현실화시키기는 어려워 보인다. 본 논문에서는 기존의 입출력 시스템과 하위 호환성을 유지할 수 있도록 물리적인 섹터 정보만을 이용하여 멀티미디어 부하를 판별하고 이를 기반으로 디스크의 동작을 멀티미디어 재생에 동적으로 최적화시키는 방법을 제안한다. 다양한 입출력 부하로부터 멀티미디어 부하를 지능적으로 분류하기 위해 기계 학습 분야에서 사용되고 있는 부스팅 알고리즘을 사용하였다 부스팅 알고리즘을 통해 구축된 최종 학습기를 이용하여 최근에 발생한 입출력 부하가 멀티미디어 부하라면, 디스크는 보다 많은 섹터를 미리 읽음으로써 멀티미디어 부하에 대한 디스크 활용율을 극대화한다. 이러한 지능형 입출력 서브 시스템을 차후에 멀티미디어 기기에 탑재되는 디스크 드라이브의 내부에 존재시킴으로써 호스트에 부가되는 부하없이 멀티미디어 데이타 재생에 대해 보다 효율적으로 디스크를 구동시킬 수 있다. 또한, 이러한 결과로 저자원 모바일 기기에서 보다 고화질의 멀티미디어를 재생할 수 있게 된다.

• 한국임상수의학회지
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• 제24권2호
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• pp.182-191
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• 2007

Bioabsorbable devices have been utilized and experimented in many aspects of orthopaedic surgery. Depending upon their constituent polymers, these materials can be tailored to provide sufficient rigidity to allow bone healing, retain mechanical strength for certain period of time, and then eventually begin to undergo degradation. The objective of this study was to estimate extent in which Poly-L-latic acid (PLLA) implants had bioabsorbability and biocompatibility with bone and soft tissue in dogs and also to develop bioabsorbable, biocompatible materials with the appropriate strength and degradation characteristics to allow for regular clinical use for treating orthopedic problems in humans as well as animals. Eighteen dogs were used as experimental animals and were inserted two types of PLLA implants. PLLA rods were inserted into subcutaneous tissue of back or the abdomen wall. And the rods were tested for material properties including viscosity, molecular weight, melting point, melting temperature, crystallinity, flexural strength, and flexural modulus over time. PLLA screws were inserted through cortical bone into bone marrow in the femur of the dogs and stainless steel screw was inserted in the same femur. Radiographs were taken after surgery to observe locations of screw. Histological variations including cortical bone response, muscular response, bone marrow response were analyzed over the time for 62weeks. The physical properties of PLLA rods had delicate balances between mechanical, thermal and viscoelastic factors. PLLA screws did not induce any harmful effects and clinical complications on bone and soft tissue for degradation period. These results suggest that PLLA implants could be suitable for clinical use.

• 한국컴퓨터정보학회논문지
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• 제20권3호
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• pp.81-88
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• 2015

최근 보안(security)분야는 클라우드 컴퓨팅(cloud computing)이나 사물 인터넷(internet of things) 등과 같은 다양한 기술들이 등장하면서 중요성이 더욱 부각되고 있다. 이러한 가운데 국내에서는 보안 분야를 정보 보안(information security)과 물리 보안(physical security), 융합 보안(convergence security)으로 분류하고 있으며, 이와 같은 국내 보안 분류체계는 산업 분야별 현황 분석 및 통계와 로드 맵 등에 매우 중요한 기준이 되고 있다. 이러한 분류체계 중, '융합 보안'은 다양한 산업 분야로부터 많은 주목을 받고 있으나, 국내에서는 '융합 보안'에 대한 분류체계를 관련 기관별로 달리 하고 있어, 데이터의 정확성과 호환성 등에 신뢰성이 결여되는 등의 문제로 체계적인 보안 분야의 분류체계가 필요한 실정이다. 따라서 본 논문은 국내의 분류체계의 현황과 특징들을 사례를 통해 비교 분석함으로써, 분류 항목의 추가 및 삭제가 용이하고, 새로운 기술동향에 적합한 확장이 용이하도록 향상된 분류체계를 제안하고자 한다. 향후, 제안하는 분류체계는 국내 보안 분류체계의 구축을 위한 자료로 활용될 것으로 기대한다.

• 한국안전학회지
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• 제30권1호
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• pp.137-143
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• 2015

Fire fighter are exposed to the situations which are hard to predict due to continuous and accidental changes which hinder their fire fighting activity. As these threats of safety accident act as fear factors, they are doing insecure fire fighting activities. Therefore, as unclear and abnormal risks of working environment such as the riskiness of expansion of disaster, instability, obstacles of activities, abnormality, urgency, etc. increase, safety accidents are caused. This study analyzes the actual condition of safety and health and awareness of fire fighter who are exposed safety accidents during their fire fighting activities and utilize such result as the basis data to secure safety of fire fighter, keep efficient safety control and prevent accidents. The results of analysis are as follows. As rescue works among all fire-fighting works shows the highest emotional stabilization and the highest post-traumatic stress disorder is shown in fire sergeant level positions, and fire fighters whose working period is 10-15 years, reinforcing safety training to long-term workers is necessary. As the result of survey regarding safety awareness, the highest awareness level was shown in fire sergeant level positions, and fire fighters whose working period is over 20 years, and when it comes to operation of fire fighting equipments, fire-fighting workers and workers having 1-4 years of working period showed high safety awareness. The more serious injury in a fire fighter experienced as the first injury after working as a fire-fighter, the more cause-and-effect relationship was shown between personal physical condition and work, and it is shown as obstacles of fire fighting activities and affects to post-traumatic stress disorder. Moreover, as after-work off duty activities also affect to official disaster, systematic improvement of working environment is required. Occupational medical work compatibility evaluation considering the distinct characteristics of works to secure fire-fighter' health care together with fire-fighting capability is shown to be necessary.

• 한국IT서비스학회지
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• 제14권2호
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• pp.289-314
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• 2015

Recently, Most of the companies and government offices are under consideration about the adoption of cloud office service to actualize the smart work policies. Comparing with traditional office software, a cloud office service have the advantage of the method of payment and coming over the physical limitations. Many cloud office service users tend to adopt an official evaluated the service without doubt. However after deciding to adopt cloud office service, many users are faced with a variety of problems and difficulties practically. In this study, researchers carried out interview about those problems and difficulties after adopting a cloud office service. Consequently, there are several problems and difficulties such as compatibility, document security, document lost and maladjusted to the new graphic user interface between traditional office software and a cloud office service. A cloud office service have still several advantages not only a competitive price but also ubiquitous attributes. Thus, researchers need to study about what kinds of reason variables can solve those problems and difficulties. In existing research, DeLone & McLean have suggested information system success model. They use three independent variables which are system quality, information quality, service quality. Parameters are user satisfaction, intention to use and use. Lastly, dependent variables are net benefits. However in this study, we need to change the scope of measurement. In other words, we have to replace parameters with dependent variables. Simply, user satisfaction, intention to use and use is going to be dependent variables. There are several reasons why we need changing variables. First, we aim at giving a some suggestions to a cloud service providers which independent variables do not work to satisfy for the users. Second, we need to find out how to maximize cloud office service user's satisfaction and intention to use. Third, we should firstly know that relationship between independent variables and dependent variables. Finally, those research results give for the cloud office service provider to solve the cloud office service adopting problems and difficulties.

• Tribology and Lubricants
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• 제36권3호
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• 한국융합학회논문지
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• 제11권8호
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• pp.115-122
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• 2020

본 연구는 야간 라이딩을 위한 패브릭 일렉트로닉스 기반의 안전 보호용 스마트 애슬레져 패션 개발 연구를 목적으로 하며 인간 친화성이 강화된 Fabric LED Display와 Fabric Capacitive touch sensor를 전도성 원사를 개발 및 활용하여 탈·부착 형태로 설계하여 구현하였다. 이러한 모듈의 탈·부착성은 다른 애슬레져 제품과 기능적·심미적인 요소를 교환 및 호환을 할 수 있도록 설계하여 기능뿐만 아니라 디자인의 다양화가 가능한 커스터마이즈 시스템으로 기존 제품들과 차별화된 스마트 애슬레져 패션 제품을 제안하였다는 점에서 연구의 의의가 있다. 후속 연구에서는 Fabric Electronics를 활용하여 착용성과 유연성이 강화된 직물의 물리적 속성에 적합한 직물센서를 개발하고 이를 활용한 커스터마이즈 스마트 패션을 제시할 예정이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.859-865
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• 2007

This paper presents a method to analyze the unbalance response of a high speed polygon mirror scanner motor supported by sintered bearing and flexible supporting structures by using the finite element method and the mode superposition method. The appropriate finite element equations for polygon mirror are described by rotating annular sector element using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. The rotating components except for the polygon mirror are modeled by Timoshenko beam element including the gyroscopic effect. The flexible supporting structures are modeled by using a 4-node tetrahedron element and 4-node shell element with rotational degrees of freedom. Finite element equations of each component of the polygon mirror scanner motor and the flexible supporting structures are consistently derived by satisfying the geometric compatibility in the internal boundary between each component. The rigid link constraints are also imposed at the interface area between sleeve and sintered bearing to describe the physical motion at this interface. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem by using the restarted Arnoldi iteration method. Unbalance responses in time and frequency domain are performed by superposing the eigenvalues and eigenvectors from the free vibration analysis. The validity of the proposed method is verified by comparing the simulated unbalance response with the experimental results. This research also shows that the flexibility of supporting structures plays an important role in determining the unbalance response of the polygon mirror scanner motor.