• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.352-354
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• 2000

The induction motor is a high-efficiency machine when working close to its rated operation point. This paper uses a simple induction motor model that includes iron losses. The model, which only requires the knowledge of conventional induction motor parameters, is referred to a field-oriented frame. At steady-state light-load condition the minimum point of the input power can be found with the condition that it is possible to obtain the same torque with different combinations of flux and current values. Using the minimum point. the drive system with the proposed efficiency optimization controller can be controlled easily. Simulation and experimental results show the effectiveness of the control strategy proposed for an induction motor drive.

• 한국보건간호학회지
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• 제4권1호
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• pp.37-55
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• 1990

Every country in the world has been trying to expand the basic health right for the peoples as W.H.O has established the goal 'health for AU' by the year of 2000. Related to this goal, our government authority has establish the policy 'the insurance of health for all' into effect from July 198\). Recently hospitalshave been making a ceaseless effort for the plan for the rationalization of its management the academic World is making it a subject of discussion by doing the secure of manpower at a resonable level and the increase of productivity by the manpower. As a result of the efforts the study was established to secure the numbers of nursing manpower at a resonable level and use the unskilled persons at the utilizing field and seek the possible area of their activity for more efficient service through the investigation of ablity of simple nursing activities of regiestered nurses and nurse aides for rational function according to the educational levels and talents. The method of study was established by the registered nurses and nurse and nurse aides(R.N 229, N.A 226) who are working in 15 hospitals with over 200 beds. This surrey was conducted from Mar 29, 1989 to April 8, 1989. The method to test the degree of importance, difficulties, and the abillity of performance of a simple nursing activities was classified into 35 activities on the basis of references on this field. The degree of importance was composed from point l(Not so important) to 5(Very important). the degree of difficulties. was composed as follows; very easy - Point 1 very difficult and complicated - Point 5. and the ability of performance was composed from point 1 to 5. The materials gathered through the survey were analyzed with frequency, mean standard deviation, percentage. t-test, Anova, pearson's coefficient of correlation, stepwise multiple regression. factor analysis, discriminant analysis. The obtained results are summarized as follows: 1. The recognition values of the simple nursing activities of each group of registered nurse and nurse aides show; The degree of importance; 4.04 and 4.26 The degree of difficulties; 2.72 and 2.94 The ability of performance; 2.07 and 2.38 The brief summary shows there are little differences between who two groups the simple nursing activities turned out to be easy and simple work. 2. Regardless of the degree of importance, and difficulties, the ability of performance the important in fluencing of the degree of the simple nursing activities between the registered nurses and nurse aides was the order of educational level, hospital career, working career in wards and ages of the registered nurses and ages and hospital creer of nurse aides. The result was that the simple nursing activities could easily be familiar through the training of their working environment and period of experience. 3. Among the 35 simple nursing activities the items capable of resonable entrusting to the nurse aides are 5 that is helping bed-bathing, 8itz Bath, using bed pan, care while delivering patient, accompaying patient when visitor's check. There wasn't and differences between RN and nurse aides in performing the above 5 items. In anywhere. so we can say obviosuly that this nursing activities should be performed under the nursing system of which chief of nurse are supposed to supervise nurse aides as a possible function to be entrusted. In view of the above mentioned results, therefore, this partial functional job of the simple nursing activities can able be entrusted to the nurse aides through the regular training course. In case of these functional activities could be entrusted under, the responsibility of registered nurse, we can able suggest to for that there are the following advantages: 1.. In the nursing activities-affairs, the qualified guarantee of the nursing services can be kept and increased or promotoed with accommodation of the required nursing service and roles being expanded presently. 2. In the productivity of the hospital manpower, therefore, we have comt to view and consider in favourly that when an automational administration times would be come in the near future time to hospital affairs as a reality, to utilize the existing nures aides is better rather than investing so as to develop the other source manpowers or seek its for the efficient business management in the operational strategy or its policy.

• Journal of Advanced Marine Engineering and Technology
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• 제40권6호
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• pp.476-483
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• 2016

해양온도차발전용 유기랭킨사이클은 해양의 표층수와 심층수사이의 온도차를 이용하여 발전하는 사이클이다. 작동유체는 유기랭킨사이클의 열역학적 성능에 있어 중요한 요소이다. 유기랭킨사이클의 열역학적 분석방법으로 핀치포인트분석이 있다. 본 연구는 열교환기내 핀치포인트온도차의 변화와 열원 및 열침의 출구온도의 변화에 따른 열역학적 성능분석을 수행하였다. 핀치포인트분석법에 따라 설계한 해양온도차발전용 단순랭킨사이클에 7종의 단일 작동유체를 적용하여 열역학적 성능을 분석하였다. 성능분석결과 열교환기에서 핀치포인트온도차와 열원 및 열침의 온도변화가 작을수록 사이클 총 비가역성 및 총 엑서지 파괴인자가 감소하였으며, 제2법칙 효율은 상승하였다. 또한 비가역성은 열역학적 변화가 발생한 곳에서 크게 변화하였다. RE245fa2는 선정한 작동유체 중에서 가장 우수한 열역학적 성능을 보여주었으며, 모든 작동유체의 성능은 유사하였다. 열교환기 및 작동유체 선정에 있어 열역학적 성능과 함께 다양한 요소들에 대해서도 엄밀한 이론적 근거가 필요하다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제1권1호
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• pp.35-43
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• 1997

Handling the emergency problems such as Chemobyl accident require real time prediction of pollutants dispersion. One-point real time sounding at pollutant source and simple model including turbulent-radiation process are very important to predict dispersion at real time. The stability categories obtained by one-dimensional numerical model (including PBL dynamics and radiative process) are good agreement with observational data (Golder, 1972). Therefore, the meteorological parameters (thermal, moisture and momentum fluxes; sensible and latent heat; Monin-Obukhov length and bulk Richardson number; vertical diffusion coefficient and TKE; mixing height) calculated by this model will be useful to understand the structure of stable boundary layer and to handling the emergency problems such as dangerous gasses accident. Especially, this simple model has strong merit for practical dispersion models which require turbulence process but does not takes long time to real predictions. According to the results of this model, the urban area has stronger vertical dispersion and weaker horizontal dispersion than rural area during daytime in summer season. The maximum stability class of urban area and rural area are 'A' and 'B' at 14 LST, respectively. After 20 LST, both urban and rural area have weak vertical dispersion, but they have strong horizontal dispersion. Generally, the urban area have larger radius of horizontal dispersion than rural area. Considering the resolution and time consuming problems of three dimensional grid model, one-dimensional model with one-point real sounding have strong merit for practical dispersion model.

• Journal of Korean Neurosurgical Society
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• 제58권1호
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• pp.9-13
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• 2015

Objective : To improve pedicle screw placement accuracy with minimal radiation and low cost, we developed specially designed K-wire with a marker. To evaluate the accuracy of thoracolumbar pedicle screws placed using the novel guide-pin and portable X-rays. Methods : Observational cohort study with computerized tomography (CT) analysis of in vivo and in vitro pedicle screw placement. Postoperative CT scans of 183 titanium pedicle screws (85 lumbar and 98 thoracic from T1 to L5) placed into 2 cadavers and 18 patients were assessed. A specially designed guide-pin with a marker was inserted into the pedicle to identify the correct starting point (2 mm lateral to the center of the pedicle) and aiming point (center of the pedicle isthmus) in posteroanterior and lateral X-rays. After radiographically confirming the exact starting and aiming points desired, a gearshift was inserted into the pedicle from the starting point into the vertebral body through the center of pedicle isthmus. Results : Ninety-nine percent (181/183) of screws were contained within the pedicle (total 183 pedicle screws : 98 thoracic pedicle screws and 85 lumbar screws). Only two of 183 (1.0%) thoracic pedicle screws demonstrated breach (1 lateral in a patient and 1 medial in a cadaver specimen). None of the pedicle breaches were associated with neurologic or other clinical sequelae. Conclusion : A simple, specially designed guide-pin with portable X-rays can provide correct starting and aiming points and allows for accurate pedicle screw placement without preoperative CT scan and intraoperative fluoroscopic assistance.

• 한국멀티미디어학회논문지
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• 제21권2호
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• pp.300-309
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• 2018

Detection of vanishing point is a challenging task in the situations where there are several structures with straight lines. Commonly used approaches for determining vanishing points involves finding the straight lines using edge detection and Hough transform methods. This approach often fails to perform effectively when there are a lot of straight lines found. The lines not meeting at a vanishing point are considered to be noises. In such situation, finding right candidate lines for detecting vanishing points is not a simple task. This paper proposes to use reference objects for vanishing point detection. By analyzing a reference object, it identifies the contour of the object, and derives a polygon from the contour information. Then the edges of the detected polygon are used to find the vanishing points. Our experimental results show that the proposed approach can detect vanishing points with comparable accuracy to the existing edge detection based method. Our approach can also be applied effectively even to complex situations, where too many lines generated by the existing methods make it difficult to select right lines for the vanishing points.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1986-1995
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• 2018

In this paper, a novel neutral-point voltage balancing scheme for NPC three-level inverters using carrier-based sinusoidal pulse width modulation (SPWM) method is developed. The new modulation approach, based on the obtained expressions of zero sequence voltage in all six sectors, can significantly suppress the low-frequency voltage oscillation in the neutral point at high modulation index and achieve a fast voltage-balancing dynamic performance. The implementation of the proposed method is very simple. Another attractive feature is that the scheme can stably control any voltage difference between the two dc-link capacitors within a certain range without using any extra hardware. Furthermore, the presented scheme is also applicable to the single-phase NPC three-level inverter. It can maintain the neutral-point voltage balance at full modulation index and improve the voltage-balancing dynamic performance of the single-phase NPC three-level inverter. The performance of the proposed strategy and its benefits over other previous techniques are verified experimentally.

• 한국지능시스템학회논문지
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• 제24권4호
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• pp.355-359
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• 2014

본 논문은 단순한 후반부 구조를 가진 퍼지 모델을 계층적 구조로 결합한 퍼지 패턴 분류기를 제안한다. 계층적 구조를 가진 퍼지 패턴 분류기의 기본 구조는 단순한 후반부 구조를 가진 퍼지 모델을 사용하여 전체 패턴 분류기의 구조적 복잡성을 높이지 않도록 설계 하였다. 입력공간을 계층적으로 분할하기 위하여 대표적인 퍼지 클러스터링 알고리즘인 Fuzzy C-Means clustering 기법을 이용하였다. 분할된 퍼지 입력 공간의 하위 구조를 분석하기 위하여 conditional Fuzzy C-Means 클러스터링 기법을 이용하였다. 계층적으로 분할된 퍼지 입력공간에 간단한 구조를 가진 퍼지 패턴 분류기를 적용하여 계층적 구조를 가진 패턴 분류기를 설계한다. 계층적으로 퍼지 모델들을 결합함으로써 입력 공간의 정보 분석을 거시적인 관점에서 시작하여 세부적으로 분석이 가능하게 되었다. 제안된 퍼지 패턴 분류기의 성능을 평가하기 위하여 다양한 기계 학습 데이터를 사용하였다.

• 대한수학회논문집
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• 제9권4호
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• pp.933-944
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• 1994

Let $\pi : P \to S^4$ be a principal G-bundle over $S^4$ whose the structure group G is a compact, connected, simple Lie group. Since $\pi_3(G) = \pi_4 (BG) = Z$, we can classify the principal bundle $P_k$ over $S^4$ by the map $S^4 \to BG$ of degree k. Atiyah and Jones [2] showed that $C_k = A_k/g^b_k$ is homotopy equivalent to $\Omega^3_k G \simeq \Omega^4_k BG$ where $A_k$ is the space of the all connections in $P_k$ and $g^b_k$ is the based gauge group which consists of all base point preserving automorphisms on $P_k$. Here $\Omega^nX$ is the space of all base-point preserving continuous map from $S^n$ to X. Let $M_k$ be the space of based gauge equivalence classes of all connections in $P_k$ satisfying the Yang-Mills self-duality equations, which we call the moduli space of G instantons.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.972-977
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• 1998

This paper deals with stand-alone Photovoltaic system(SPVS) with charge and discharge controller. Main power source of SPVS are generally solar cell and battery. Therefore SPVS can be classified into variable types in accordance with connection method between battery and solar cell array. Mainly used one of them is direct connection type which has advantages such as simple structure and simple controller. However most big drawback of this system is energy loss by voltage disharmony between solar cell array and battery. Therefore SPVS with charge and discharge controller which can operate solar cell array at maximum power point is designed and experimented with a laboratory prototype.