• 한국정밀공학회지
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• 제17권11호
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• pp.151-157
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• 2000

The MRAC theory has proved to be one of the most popular algorithms in the field of adaptive control, particularly for practical application to devices such as an hydraulic servosystem of which parameters are unknown or varying during operation. For small sampling period, the discrete time system becomes a nonminimal phase system. The $\delta$-MRAC was introduced to obtain the control performance of nonminimal phase system, because the z-MRAC can not control the plant for small sampling period. In this paper, $\delta$-MRAC is applied to the control of an hydraulic servosystem which is composed of servovalve, hydraulic cylinder and inertia load.

• 한국분말재료학회지
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• 제4권1호
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• pp.55-62
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• 1997

Flow and heat transfer characteristics of gas, and trajectories and cooling characteristics of droplets/particles in a gas atomizer were investigated by a numerical simulation using FLUENT code. Among several kinds of solution method, the k-$\varepsilon$ turbulent model, power-law scheme, SIMPLE algorithm is adopted in this study. Momentum and heat exchange between a continuous phase(gas) and a dispersed phase(particle) were taken into account. Particle trajectories are simulated using the Lagrangian method, and Rosin-Rammler formula is used for the particle size distribution. Streamlines, velocities and pressures of gas, and trajectories, velocities and cooling rates of particles have been investigated for the various gas inlet conditions. Small but very intensive recirculation is found just below the melt orifice, and this recirculation seems to cause the liquid metal to spread radially. Particle trajectory depends on the particle size, the location of particle formation and the turbulent motion of gas. Small particle cools down rapidly, while large diameter particles solidify slowly, and this is mainly due to the differences in thermal inertia.

• 한국해양공학회지
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• 제29권1호
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• pp.1-8
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• 2015

An analytical model of liquid sloshing is developed to consider the energy-loss effect through a partially submerged porous baffle in a horizontally oscillating rectangular tank. The nonlinear boundary condition at the porous baffle is derived to accurately capture both the added inertia effects and the energy-loss effects from an equivalent non-linear drag law. Using the eigenfunction expansion method, the horizontal hydrodynamic force (added mass, damping coefficient) on both the wall and baffle induced by the fluid motion is assessed for various combinations of porosity, submergence depth, and the tank's motion amplitude. It is found that a negative value for the added mass and a sharp peak in the damping curve occur near the resonant frequencies. In particular, the hydrodynamic force and free surface amplitude can be largely reduced by installing the proper porous baffle in a tank. The optimal porosity of a porous baffle is near P=0.1.

• 한국군사과학기술학회지
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• 제4권2호
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• pp.147-156
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• 2001

In this paper, a robust attitude control scheme based on Eigenaxis rotation for the spacecraft is proposed. Eigenaxis rotation transforms the attitude of spacecraft to the shortest path and is represented by quaternion. The control law consists of PD-type control part for the nominal system and the robust control part for compensating inertia uncertainty. For the proposed controller, stability analysis is performed and the performance is shown via computer simulation.

• 한국소음진동공학회논문집
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• 제14권6호
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• pp.486-494
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• 2004

This paper addresses the dynamic modeling and closed-loop eigenvibration analysis of composite rotating pretwisted fan blade modeled as non-uniform thin-walled beam with bi-convex cross-section fixed at the certain presetting angle and incorporating piezoelectric induced damping capabilities. The blade model incorporates non-classical features such as transverse shear, rotary inertia and includes the centrifugal and Coriolis force field. A velocity feedback control law relating the piezoelectiriccally induced transversal bending moment at the beam tip with the appropriately selected kinematical response quantity is used and the beneficial effects upon the closed loop eigenvibration of the blade are highlighted.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.729-734
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• 2000

This paper proposes virtual-magnetic system by a force-reflecting interface to drive a ultrasonic motors(USMs) To approach virtual magnet in graphic the 6 dDOF force-reflecting interfaces provides force feedback to users as if I is magnetic-force, So users can feel real magnet Effectively to display the magnetic-force we need the interface with specific characteristics such as low inertia almost zero friction and very high stiffness As an actuator for the interface the USMs have many good advantage satisfied these conditions over conventional servo motors. To estimate capability of this virtual-magnetic system we did an experiment of magnetism based on coulomb's law when Coulmb's low apply this experiment it is vey conformable to real magnet

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2003년도 춘계학술발표논문집 (상)
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• pp.515-518
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• 2003

멀티미디어 데이터베이스 시스템의 구현 과정 중 제일 첫 번째 단계라 할 수 있는 장면전환의 검출은 비디오 데이터베이스 시스템에서뿐만 아니라 비디오 검출, 비디오 압축 비디오 문서의 군집 화 등 여러 분야에서 유용하게 다루어지고 있고. 또 이미 많은 알고리즘들이 개발되어 있다. 이미 개발되어져 있는 알고리즘들을 구현 비교하는 과정에서, 제시된 알고리즘들은 부분적으로는 장면전환의 정확한 검출을 하고 있으나 잡음이 삽입되거나 특수한 상황에서는 잘못된 견과를 나타내고 있다. 실세계에서 적용되는 뉴턴의 제 1법칙인 관성의 법칙이 지니는 특성을 장면전화 검출에 적용시키고자 하였다. 제시된 알고리즘의 성능을 증명하기 위하여, 본 논문에서는 이미 발표된 여러 알고리즘들의 성능과 관성의 법칙을 적용시킨 알고리즘의 성능을 비교하였다.

• 대한지리학회지
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• 제36권4호
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• pp.356-381
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• 2001

본 연구는 세가지 목적을 갖는다. 하나는 한국과 일본의 인구요소를 분석함에 있어 비교규준을 제공해주는 신말사스론과 풍요론의 양립할 수 없는 개념을 분석하는 것이며. 다른 하나는 다양한 인구요소들이 한국과 일본이라고 하는 특정지역과 어떻게 관련되고 있는가를 구명하는 것이다. 마지막으로 50세 이상의 노령인구의 거주선호유형과 장래의 근심도를 비교, 분석하는 것이다. 다양한 인구요소의 분석을 통해서 일본은 한국보다 인구선진형이지만 양자간의 격차는 매년 줄어져감을 알 수 있다. Willer의 이동기대치는 한국이 일본보다 월등 높다는 사실이 광주.전남과 히로시마현의 사례지역에서 발견된다. 일본의 매장문화는 이미 사라졌으나 한곽은 화장률이 아직도 30% 수준 밖에 되지 않아 사망으로부터 오는 인구감소효과를 상실하고 있다. 50세 이상 노인(또는 예비노인)의 거주선호유형에 관한 사례연구를 통해 일본이 한국보다 더 의존형이며, 독거의 외로움이 그 첫째 이유가 되는 것은 양국의 공통적 현상이다 미래에 대한 근심도 역시 일본이 한국보다 현저히 높다. 이것들은 여러측면에서 연령.학력.지역(시.군)과 관련된다. 노령사회에서의 노동력부족이라는 일반적 인식은 잘못된 관념에 불과하다. 그것은 노동력 부재가 아닌, 노인으로부터의 노동력 탈취에서 오는 것이기 때문이다. 인구현상에는 관성의 법칙이 적용되므로 미세한 인구변화에도 주의를 요한다. 말사스적 사고는 아직도 유효하며, 인구.자원.환경문제는 더 이상 개인이나 지역문제가 아닌 전 지구촌의 문제라는 인식이 중요하다.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.237-244
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• 2016

Background: Korea Atomic Energy Research Institute is developing a fission product transport module for predicting the behavior of radioactive materials in the primary cooling system of a nuclear power plant as a separate module, which will be connected to a severe accident analysis code, Core Meltdown Progression Accident Simulation Software (COMPASS). Materials and Methods: This fission product transport (COMPASS-FP) module consists of a fission product release model, an aerosol generation model, and an aerosol transport model. In the fission product release model there are three submodels based on empirical correlations, and they are used to simulate the fission product gases release from the reactor core. In the aerosol generation model, the mass conservation law and Raoult's law are applied to the mixture of vapors and droplets of the fission products in a specified control volume to find the generation of the aerosol droplet. In the aerosol transport model, empirical correlations available from the open literature are used to simulate the aerosol removal processes owing to the gravitational settling, inertia impaction, diffusiophoresis, and thermophoresis. Results and Discussion: The COMPASS-FP module was validated against Aerosol Behavior Code Validation and Evaluation (ABCOVE-5) test performed by Hanford Engineering Development Laboratory for comparing the prediction and test data. The comparison results assuming a non-spherical aerosol shape for the suspended aerosol mass concentration showed a good agreement with an error range of about ${\pm}6%$. Conclusion: It was found that the COMPASS-FP module produced the reasonable results of the fission product gases release, the aerosol generation, and the gravitational settling in the aerosol removal processes for ABCOVE-5. However, more validation for other aerosol removal models needs to be performed.

• 한국의료질향상학회지
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• 제29권2호
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• pp.15-31
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• 2023

Purpose: This study aimed to identify the characteristics of patient safety incidents (PSIs) related to nursing and to provide primary data for preventing the recurrence of similar incidents. Methods: This secondary analysis study included damage claims rulings filed for clinical negligence from 2014 to 2018 that contained the keyword 'nurse'. It excluded judgments irrelevant to nursing care and in which clinical negligence or causal damages were overruled. A total of 93 cases were analyzed. The characteristics of PSIs were derived through descriptive statistics, and two instances of nursing-related PSIs were examined by qualitative content analysis focusing on root causes. Results: The analysis of PSIs related to nursing suggested that the medical institutions where the PSIs occurred most frequently were hospitals, and the most common types of PSIs were medication, surgery, and treatment/procedure, in that order. In addition, it indicated that nursing-related PSIs occurred most frequently in general wards during the day shift, with the most common related nursing practice being managing potential risk factors. The qualitative analysis showed that careless monitoring and institutional inertia were causes of PSIs. Conclusion: To prevent nursing-related PSIs, nurses need to individually monitor and assess patient conditions. In addition, support should be accompanied by the improvement in the systems in place aimed at preventing the recurrence of nursing-related PSIs at the institutional and national level, such as securing appropriate nursing personnel and improving labor conditions.