• 한국정밀공학회지
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• 제19권2호
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• pp.213-219
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• 2002

A cone-shaped active magnetic healing spindle system for high speed internal grinding with built-in motor that has 7.5kW power and maximum rotational speed of 50,000 rpm is designed and built. Using cone-shaped AMB(Active Magnetic Bearing) system, the axial rotor dick and magnets of conventional 5-axis actuating design can be eliminated. so this concept of design provides a simple magnetic bearing system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and a de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed crone-shaped AMB spindle system is built and constructed with a digital control system, which has TMS320C6702 DSP, 16 bit AD/DA, switching power amplifier and gap sensors. As the AMB system provides high damping ratio eliminating overshoot and resonance speed, this spindle runs up to 40,000 rpm stably with about 5${\mu}{\textrm}{m}$ of runout.

• 경영과정보연구
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• 제34권5호
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• pp.277-293
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• 2015

저축은행은 서민의 금융기관으로서 일반은행에 비하여 규모가 작고 상대적으로 리스크 관리도 취약하다. 또한 일반 은행과 같이 예금자보호법에 따라 5천만원 이하의 예금은 보호되기는 하지만 일반서민이나 중소기업이 주된 고객이라는 점에서 일반 기업과 차이가 있다. 따라서 지배주주의 사적이익추구로 인하여 극단적으로 영업정지등의 사태가 발생할 경우 그로 인한 이익의 침해는 소액주주 이외에도 다수의 예금자, 정부, 일반 국민들도 잠재적인 피해를 볼 수 있고 그로 인한 공익비용은 일반기업보다 훨씬 크다 할 수 있다. 지배주주의 지분율과 관련한 가설로 이익침해가설과 이해일치가설로 상반되는 주장이 존재한다. 먼저, 외부 소액주주들에 대한 지배주주의 이익침해가설(expropriation of minority shareholder hypothesis)에서는 지배주주의 지분율이 증가할수록 경영자는 이익을 증가시켜 보고할 유인이 있다. 또한 이해일치가설(convergence of interest hypothesis)은 지배주주 지분율이 증가함에 따라 경영자는 이익을 감소시켜 보고할 유인이 있다. 이에 본 연구는 국내 상호저축은행 대상으로 최대주주 지분율이 기업의 내부통제의 질에 어떠한 영향을 미치는 지에 대한 실증적 연구를 수행하고자 한다. 분석 결과, 최대주주지분율은 내부회계관리제도 취약점 공시에 유의적인 양(+)의 영향을 미치는 것으로 나타났다. 이것은 최대주주지분율이 높을수록 회계투명성이 저하되어 내부통제의 질이 낮아져서 내부회계관리제도 취약점 보고가능성이 높아진다는 것을 의미한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1120-1125
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• 2007

Experimental study on the control of randomly disturbing system is conducted. External and internal disturbances are imposed to the system in combined manner. A vertical propeller system exposed horizontal weak turbulent air flow is chosen as an experimental model. The aim of the control system is to maintain the angular position of vertical propeller in parallel to air flow. Trajectory Tracking Stochastic Controller (TTSC) is designed to ensure system's stability while following system command. The Trajectory Tracking Stochastic Controller is composed of two controller, one is stochastic controller to suppress internal random noise and the other one is trajectory-tracking controller to follow the command having random noise. The proposed hybrid controller, TTSC, shows remarkable performance in pitch control of vertical propeller system in wind-tunnel test

• 대한한방내과학회지
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• 제27권1호
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• pp.114-125
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• 2006

objective : The purpose of this research is to examine the effects of Scutellaria Radix(SR) extract on immune cells and cytokines in ovalbumin(OVA)-induced asthmatic mice. Methods : In vivo, C57BL/6 mice were sensitized and handicapped by OVA for 9 weeks. In this experiment, one group was not treated, and the other group was treated with SR extract for six weeks(five times per week) and analyzed by ELISA and flow cytometer. Results : In vivo, there were significant decreases in eosinophils, IL-4, IL-13 in BALF (bronchoalveolar lavage fluid) compared with that of control group. However,$IFN{\gamma}$ in the SR group increased significantly compared with that of control group. Additionally, the population of $CD3e^-/CCR3^+,\;CD69^+/CD3e^+,\;IgE^+/B220^+,\;CD11b^+/Gr-1^+$ cells in the SR group decreased compared with that of control group. conclusion : The results of this study support a role for SR as an effective treatment for asthma in its experimental success in significantly decreasing inflammation and asthma reactions, and in increasing $IFN{\gamma}$, Which helps prevent such reactions.

• 동력기계공학회지
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• 제12권5호
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• pp.65-70
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• 2008

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the turbine major valves relating to safety for turbine operating and prevention of turbine trouble at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized electro-hydraulic control oil flowed through turbine electro-hydraulic controller oil check valve and turbine power/trip fluid solenoid valve in the condition of actual turbine operating. The acoustic emission method was applied to the valves at the site, and the background noise was measured far the abnormal plant condition. To judge for the leak existence ell the object valves, voltage analysis and frequency analysis of acoustic signal emitted from infernal leak in the valve operating condition are performed. It was conformed that acoustic emission method could monitor for valve internal leak to high sensitivity.

• 대한한방내과학회지
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• 제25권2호
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• pp.298-306
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• 2004

Objective : The main purpose of this study was to determine if Rehmanniae Radix has significant effects on lung fibrosis. Materials and Methods : C57BL/6J mice were devided into three groups. These were the normal group, which were not treated, the control group, given Intratracheal instillation(IT) of Bleomycin, the sample group, given IT of bleomycin and water-extracted Rehmanniae Radix. Animals were sacrificed 14 days after IT treatment. Lung fibrosis was evaluated by analysis of bronchoalveolar larvage(BAL) total WBC, percentage of macrophage, lymphocyte and neutrophil. This was done histologically by semiquantitative histological index(SHT) of lung tissue. Results : The sample group in coparison with control group showed a decrease in the BAL, total WBC, lower percentage of lymphocyte and neutrophil(p<0.05) and correspondingly a lower percentage of macrophage(p<0.01). The Sample group showed a significant decrease of collagen accumulation with respect to the control group in SHI of lung tissue(p<0.01). INF-${\gamma}$ and IL-4 levels in BALF of mice significantly decreased in the control group(p<0.05). Conclusions : Results suggest that Rehmanniae Radix has an anti-imflamatory effect and anti-fibrotic effect on the lungs through decrease of IL-4 and total WBC count for not only macrophage, but also lymphocyte and neutrophil. The degradation of INF-${\gamma}$ calls for research beyond the scope of this study.

• 상하수도학회지
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• 제25권2호
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• pp.193-199
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• 2011

A method to improve internal corrosion control efficiency by adding lime and carbon dioxide, which, in turn increases the Langelier Index (LI) for filtered water at a conventional drinking water treatment plant (WTP) was investigated. The SJ WTP (Q=100,000 $m^{3}$/d) has been operating an internal corrosion control system since 2006. The system has achieved stable operation through technical development and trial and error over a period of several years. As a result of the operation, the LI of treated water has increased up to 29% by adjusting pH of filtered water to 7.8 with the addition of lime and carbon dioxide. Coupon tests in the distribution system indicated that the corrosion rate has been delayed by 24% when the internal corrosion method was implemented. The increase of LI by lime and carbon dioxide has been proven to be a practical method for controlling corrosion.

• 대한한의학회지
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• 제35권1호
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• pp.50-57
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• 2014

Objectives: The purpose of this study was to examine whether Temporomandibular Joint Balance Appliance-Golf (TBA-G) can improve postural control ability of healthy adults. Methods: Twenty participants (10 male, 10 female) aged 20 to 39 years were involved. Postural control ability of all participants was assessed before and after applying TBA-G with Balance $Master^{(R)}$ system. Modified clinical test sensory interaction on balance (mCTSIB), unilateral stance, weight bearing and rhythmic weight shift were used to evaluate postural control ability. Results: After applying TBA-G, mCTSIB on a firm plate with eyes open increased from 0.2 to 0.23 (p<0.05) but directional control was improved in slow and moderate velocity of front/back rhythmic weight shift test (P<0.05). In two cases with postural imbalance, most of the postural control measures improved after applying TBA-G. Conclusions: The results suggest that TBA-G could improve balance control ability. A larger controlled trial is needed to determine more accurately the effect of TBA-G on balance control ability.

• 대한전기학회논문지:전력기술부문A
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• 제49권3호
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• pp.95-106
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• 2000

The load frequency control of power system is one of important subjects in view of system operation and control. That is even though the rapid load disturbances were applied to the given power system, the stable and reliable power should be supplied to the users, converging unconditionally and rapidly the frequency deviations and the tie-line power flow one on each area into allowable boundary limits. Nonetheless of such needs, if the internal parameter perturbation and the sudden load variation were given, the unstable phenomenal of power system can be often brought out because of the large frequency deviation and the unsuppressible power line one. Therefore, it is desirable to design the robust neuro-fuzzy controller which can stabilize effectively the given power system as soon as possible. In this paper the robust neuro-fuzzy controller was proposed and applied to control of load frequency over multi-area power system. The architecture and algorithm of a designed NFC(Neuro-Fuzzy Controller) were consist of fuzzy controller and neural network for auto tuning of fuzzy controller. The adaptively learned antecedent and consequent parameters of membership functions in fuzzy controller were acquired from the steepest gradient method for error-back propagation algorithm. The performances of the resultant NFC, that is, the steady-state deviations of frequency and tie-line power flow and the related dynamics, were investigated and analyzed in detail by being applied to the load frequency control of multi-area power system, when the perturbations of predetermined internal parameters. Through the simulation results tried variously in this paper for disturbances of internal parameters and external stepwise load stepwise load changes, the superiorities of the proposed NFC in robustness and adaptive rapidity to the conventional controllers were proved.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1681-1686
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• 1991

In robotics and other fields of engineering, techniques for artificial reality or virtual reality are focused on and studied extensively, e.g., virtual existence for tele-operator systems in robotics, and virtual reality of designed objects in architecture. In order to realize the system we should create physical stimulations according to internal models created by experiences in a human brain. The internal model does not have to have direct connections to the real world, however, the stimulation must be signals such that the internal model are retrieved in a human brain. In this paper we propose a technique for tele-virtual reality of dynamic mechanical models, which means that one dynamic mechanical model can be shared by peoples in distant places. Since a stability issue due to time delays arises in the system, we employed a scattering technique developed for a tele-operator system and a kind of passive adaptive controllers. Furthermore, restrictions due to a simple digital implementation of the scattering transformation are discussed and some conditions for stability are shown. The proposed method is applied to a remote tug of war system and the effectiveness is verified.