• 대한임상전기생리학회지
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• 제8권1호
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• pp.31-36
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• 2010

Purpose : The purpose of this study was to investigate the effects of core exercise on the static balance for females in their twenties. Methods : The core exercise program was conducted 3 times per week for 4 weeks. The result is based on the analysis of measuring static balance before and after the core exercise program. By using the GOOD BALANCE system, the assessment of the static balance ability was made before and after the exercise of 6 postures: normal standing, one left leg?and one right leg standing with eyes open and closed respectively. For each case, the experimental data were obtained in 3 items: mean X speed, mean Y speed, and velocity moment. Statistical analysis was performed using SPSS/Win(10.0) version and Willcoxon signed rank test. Results : From the result of this study, we found that mean X speed, mean Y speed and velocity moment of total postures significantly increased after the 4 week program of core exercises. Conclusion : These finding indicate that core exercises could be beneficial to females in their twenties due to the effect of increasing static balance.

• 한국안광학회지
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• 제12권4호
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• pp.87-90
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• 2007

polycarbonate(PC)용 안경렌즈를 생산하는데 사용되는 몰드(mold)를 가공하기 위해서는 코아(core)의 가공이 필요하다. 코아의 가공은 Diamond Turning Machine(DTM) 또는 Computer Numerical Control(CNC) 선반으로 이루어지는데 이러한 장비의 운용을 위해서는 렌즈 코아 형상에 대한 수치 데이터가 필요하게 된다. 이에 우리는 렌즈 코아 형상에 대한 수치 데이터를 산출하는 프로그램을 개발하였다. 프로그램은 일반 비구면 식의 계수를 사용하여 수치 데이터를 산출할 수 있도록 개발하였으며, 형상 그래프를 보여줄 수 있도록 하였고, 필요한 수치 데이터 파일을 저장할 수 있도록 하였다.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.183-187
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• 2010

Core-Shell polymers of silicone dioxide-styrene system were prepared by sequential emulsion polymerization. In inorganic/organic Core-Shell composite particle polymerization, silicone dioxide adsorbed by surfactant sodium dioctyl sulfosuccinate (EU-DO133L) was prepared initially and then core silicone dioxide was encapsulated emulsion by sequential emulsion polymerization using styrene at the addition of potassium persulfate (KPS) as an initiator. We found that $SiO_2$ core shell of $SiO_2$/styrene structure was formed when polymerization of styrene was conducted on the surface of $SiO_2$ particles, and the concentration sodium dioctyl sulfosuccinate (EU-DO133L) was 0.5~2.0g. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• 한국정밀공학회지
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• 제27권12호
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• pp.28-32
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• 2010

Technical demands for aspheric glass lens formed in market increases its application from simple camera lens module to fiber optics connection module in optical engineering. WC is often used as a metal core of the aspheric glass lens, but the long life time is issued because it fabricated in high temperature and high pressure environment. High hard thin film coating of lens core increases the core life time critically. Diamond Like Carbon(DLC) thin film coating shows very high hardness and low surface roughness, i.e. low friction between a glass lens and a metal core, and thus draw interests from an optical manufacturing industry. In addition, DLC thin film coating can removed by etching process and deposit the film again, which makes the core renewable. In this study, DLC films were deposited on the SiC ceramic core. The process variable in FVA(Filtered Vacuum Arc) method was the substrate bias-voltage. Deposited thin film was evaluated by raman spectroscopy, AFM and nano indenter and measured its crystal structure, surface roughness, and hardness. After applying optimum thin film condition, the life time and crystal structure transition of DLC thin film was monitored.

• 동력기계공학회지
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• 제3권3호
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• pp.22-28
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• 1999

The injected liquid does not break-up instantly after injection for diesel engine. There is some unbroken portion, which is the liquid core(The length of liquid core is called the break-up length) in the spray. If the liquid core is longer than the depth of the bowl in the small DI diesel engine, the liquid core impinges on the surface of the piston. Once the liquid core impinges on the surface, it cannot ignite or burn rapidly and thus prolongs burning time with a degradation in thermal efficiency. The break-up length of a diesel spray in a compressure vessel was measured by an electric resistance method, A voltage was applied between the nozzle and screen, bar, needle electrode inserted at various axial and radial positions into atomizing sprays. As a result, a current flows not only in the region of liquid core but also through the droplets of the spray. It is found that the break-up length measured with screen electrode is overestimated. The break-up length of the spray is found to be proportional to the square root of the density ratio of fuel and surrounding gas. The break-up length of the spray decreases as the injection pressure and the back pressure increase.

• 한국정밀공학회지
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• 제28권4호
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• pp.474-481
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• 2011

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the finite element stress analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia crown were prepared. Each model contained cortical bone, trabecular bone, periodontal ligament, 4mm apical root canal filling, and post-and-core. A 50N static occlusal load was applied to the palatal surface of the crown with a $60^{\circ}$ angle to the long axis of the tooth. And three parallel type post (zirconia, glass fiber and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. For the Result of the research, the model applied glass fiber to post material has lowest von Mises stress and it is suitable for material of post core systems.

• 수산해양교육연구
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• 제23권3호
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• pp.433-444
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• 2011

The purpose of this study is to examine the task of the policy on the collecting cargoes of the Japanese container ports. Although the ports of Asia countries such as China, South Korea have increased the amount of cargoes dramatically since the latter half of 1990s, the amount of cargoes Japanese container ports deal with have increased within narrow limits. As a result of this trend, the position of Japanese ports as hub-ports has been falling down. The times of main liners linked with North America and Europe stopping at Japanese ports have continued to decrease. So Japan container ports need the policy to increase the amount of cargoes in order to avoid becoming feeder ports. This policy is to collect domestic cargoes which are transshipped in Asia ports such as Busan port from Japanese regional ports to core ports. By collecting domestic cargoes to Japanese core ports intensively, the times of international main liners stopping at Japanese core ports will increase. It's important to support the domestic liners linking between Japanese regional ports and core ports in order to collecting domestic cargoes to Japanese core ports effectively. In addition the role of Japanese government to achieve the coordination between Japanese regional ports and core ports is indispensable.

• 한국경영과학회지
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• 제32권3호
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• pp.97-114
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• 2007

IT outsourcing providers has been expanded from a single functional system to the entire IT service to gain sustainable competitiveness. This new trend of IT outsourcing need outsourcing management capability based on a firm's core capacity. Hiring external IT service providers to manage part or all of its information-related services helps a firm focus on its core business and provides better services to its clients, thus obtaining sustainable competitive advantage. This research investigates the major factors that determine the level of a particular firm's success at IT outsourcing. Based on process innovation and core-competency theories, we identify three significant components of a firm's IT outsourcing management method (ITOMM): level of core-competency-based management, maturity of outsourced tasks, and maturity of outsourcing management. Comprehensive data collection was conducted through an outsourcing association. The survey data were analyzed using a structural analysis method. Maturity of outsourced tasks and maturity of outsourcing management were found to affect project performance directly, while level of core-competency-based management only indirectly impacted project performance through its positive impact on the other two ITOMM components.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.345-352
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• 2011

This paper focuses on the properties analysis of 9mm bullet dual structure core to substitute current lead core by environment-friendly combination of W-Cu-Ni system high density composite materials. So the four combination samples were made of dual core with the different center of gravity location backward or forward compare to that of lead type bullet, and we experimented about the performance of 9mm bullet dual structure core. In the experimental results, the outer shape of core of four environment friendly samples on the target maintain marginally, while the current lead core bullets are completely crushed after hitting the target. The penetration depth of environment friendly samples excel seven times to lead type bullet and the three out of four samples with forward adjusted center of gravity penetrate deep as twice as ones backward. The impact tolerance of all four samples satisfies military specification, however, more firing tests are required to improve reliability of scattering distribution.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.52-59
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• 2012

In this paper, The cast resin transformer's vibration is measured using noncontact raser vibrometer(LV110D). The vibration characteristics of transformer windings and core are analyzed for relation between vibration magnitude and cause. Using the analysis results, the technique is presented to diagnose cast resin transformer. which is able to diagnose transformer' deformation in winding and core geometry. The magnetostriction and electromagnetic force act on the core and windings, causing them to vibrate. The vibration from windings and core penetrates into transformer cast resin and reaches the outside walls. The fundamental frequency of the core and windings vibration signal is twice that of the power frequency(120Hz). The results show that the magnitude of core vibration is linear to driving voltage amplitude and magnitude of windings vibration is increased to loading current under the some level and then stabilized.