• 호남수학학술지
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• 제8권1호
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• pp.21-49
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• 1986

A class of singular quadratic control problem is considered. The state is governed by a higher order system of ordinary linear differential equations and very general nonstandard boundary conditions. These conditions in many important cases reduce to standard boundary conditions and because of the conditions the usual controllability condition is not needed. In the special case where the coefficient matrix of the control variable in the cost functional is a time-independent singular matrix, the corresponding optimal control law as well as the optimal controller are computed. The method of investigation is based on the theory of least-squares solutions of multi-valued operator equations.

• 대한한의학회지
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• 제22권4호
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• pp.69-78
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• 2001

Objectives : It is known that cigarette smoking is associated with increased risk of both thrombotic and hemorrhagic stroke. However, in Korea, especially in the academic world of Korean Medicine, there is a lack of study about the relation between cigarette smoking and stroke. We carried out a case-control study to clarify the relation between cigarette smoking and stroke. Method : We interviewed 441 stroke patients (236 men, 205 women) as a case group and 432 non-stroke patients (208 men, 224 women) as a control group. We investigated the smoking pattern of all patients and stroke-subtype of the case group. Smoking pattern is classed into two (Class I), four (Class II) and five groups (Class III). Class I consists of current non-smokers and current smokers. Class II consists of non-smokers, former smokers, current light smokers and current heavy smokers. Class III consists of never smoked, secondhand smokers, former smokers, Current light smokers and current heavy smokers. Stroke-subtype consists of cerebral infarction and cerebral hemorrhage. Results : The percentage of current smokers of case group is higher significantly than that of control group. The number of cigarettes smoked per day is associated positively with the risk of stroke. According to our study, generally cigarette smoking is related with ischemic stroke. The percentage of secondhand smokers of the case group is lower than that of the control group. According to our study, characteristically secondhand smoking is associated with hemorrhagic stroke. Conclusions : From the above results we found that cigarette smoking is an important risk factor of stroke - especially cerebral infarction - and the number of cigarettes smoked per day is associated positively with the risk of stroke. Characteristically according to our study, secondhand smoking is associated with hemorrhagic stroke. Overall we conclude that cigarette smoking may be an important preventable factor for stroke.

• 한국전자파학회논문지
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• 제18권8호
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• pp.873-879
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• 2007

본 논문에서는 Freescale사의 Si-LDMOSFET 4-W 소자를 이용하여 고효율 class-F 전력 증폭기를 구현하였다. Class-F 전력 증폭기를 구현하는데 있어서 모든 하모닉 성분들에 대해 원하는 임피던스를 갖도록 조정하기는 불가능하기 때문에 2차와3차 하모닉 성분만을 조율하여 회로의 간결함과 동시에 상대적으로 높은 효율을 얻을 수 있었다. 또한, 본 논문에 설계된 증폭기는 보다 정확하게 하모닉 성분을 조율하기 위해, LDMOSFET의 대신 호 등가 모델에서 가장 큰 영향을 미치는 drain-source capacitance(Cds)와 bonding inductance(Lb)를 추출하여 하모닉 조율 회로를 설계하였다 제작된 고효율 class-F 전력 증폭기의 측정 결과 drain-efficiency(DE) 65.1%, power-added-efficiency(PAE) 60.3%의 효율을 얻을 수 있었다.

• 제어로봇시스템학회논문지
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• 제20권6호
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• pp.631-634
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• 2014

We propose a measurement state feedback controller for a class of nonlinear systems that have uncertain nonlinearity and sensor noise. The new design method based on the matrix inequality approach solves the measurement feedback control problem of a class of nonlinear systems. As a result, the proposed methods using a matrix inequality approach has the flexibility to apply the controller. In addition, the sensor noise can be attenuated for more generalized systems containing uncertain nonlinearities.

• 공학교육연구
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• 제15권5호
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• pp.54-59
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• 2012

It is reported that the constructivistic learning method (CLM) enhances the understanding of the students in the learning process, especially in engineering classes. In CLM-based classes, the students can take the initiative in the learning process, which is called the student-centered model of the learning process. This is different from the traditional learning method based on the teacher-centered model, where a teacher plays the central role in the learning process of students. The authors have applied the method of CLM to one of the Engineering classes, namely production planning and inventory control (PPIC) class for undergraduate students. The PPIC class provides multimedia-based study materials and factory visits as well as regular lecture sections to cover the whole subject of inventory control theory and practice. In the review sessions, students are divided into several groups, and question-and-answer discussions were actively carried out among these groups under the support of the teacher as a facilitator. It was observed that the student engagement in the class was very active compared to the conventional lecture-based classes. As for further support of students understanding on the subject, simulation-based materials are also under study for the class. This paper presents the review of case study of CLM-based PPIC class and discusses the feasibility of simulation-based study materials for further improvement of the class.

• 전자공학회논문지B
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• 제31B권8호
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• pp.47-56
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• 1994

The dynamic feedback is well-known to be much more powerful tool in control than the static one. This paper deals with the dynamic feedback linearization of the nonlinear systems which are not (static) feedback linearizable. The dynamic feedback linearization problem is however too difficult to solve at momemt. Thus we introduce a restricted class of the dynamic feedback (pure integrators followed by the static feedback) which is often used to study the problems using dynamic feedback and obtain the necessary and sufficient conditions of the linearization problem using this class of the dynamic feedback.

• Nutrition Research and Practice
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• 제14권1호
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• pp.45-54
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• 2020

BACKGROUND/OBJECTIVES: This study aimed to examine differences in weight control practices, beliefs, self-efficacy, and eating behaviors of weight class athletes according to weight control level. SUBJECTS/METHODS: Subjects were weight class athletes from colleges in Gyeong-gi Province. Subjects (n = 182) responded to a questionnaire assessing study variables by self-report, and data on 151 athletes were used for statistical analysis. Subjects were categorized into High vs. Normal Weight Loss (HWL, NWL) groups depending on weight control level. Data were analyzed using t-test, ANCOVA, x²-test, and multiple logistic regressions. RESULTS: Seventy-three percent of subjects were in the HWL group. The two groups showed significant differences in weight control practices such as frequency (P < 0.01), duration and magnitude of weight loss, methods, and satisfaction with weight control (P < 0.001). Multiple logistic regression showed that self-efficacy (OR: 0.846, 95% CI: 0.730, 0.980), eating behaviors during training period (OR: 1.285, 95% CI: 1.112, 1.485), and eating behaviors during the weight control period (OR: 0.731, 95% CI: 0.620, 0.863) were associated with weight control level. Compared to NWL athletes, HWL athletes agreed more strongly on the disadvantages of rapid weight loss (P < 0.05 - P < 0.01), perceived less confidence in controlling overeating after matches (P < 0.001), and making weight within their weight class (P < 0.05). HWL athletes showed more inappropriate eating behaviors than NWL athletes, especially during the weight control period (P < 0.05 - P < 0.001). CONCLUSIONS: Self-efficacy was lower and eating behaviors during pre-competition period were more inadequate in HWL athletes. Education programs should include strategies to help athletes apply appropriate methods for weight control, increase self-efficacy, and adopt desirable eating behaviors.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.519-523
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• 2004

In this paper, a simple power control scheme of Class-D inverter, which is varied duty cycle of fixed frequency to desired output power. It is more suitable and acceptable for high-frequency induction heating (IH) jar applications. The proposed control scheme has the advantages of not only wide power regulation range but also ease to control output power. Also it can achieve the stable and efficient Zero-Voltage-Switching (ZVS) in whole load range. The control principles of proposed method are described in detail and its validity is verified trough simulations results on 38.5kHz IGBT for induction heating rated on 1.6kW with constant frequency variable power.

• 제어로봇시스템학회논문지
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• 제10권4호
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• pp.312-316
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• 2004

In this paper, it is presented an adaptive robust control system to implement real-time control of a robot manipulator. There are Quantitative or qualitative differences between a real robot manipulator and a robot modeling. In order to compensate these differences, uncertain factors are added to a robot modeling. The uncertain factors come from imperfect knowledge of system parameters, payload change, friction, external disturbance, etc. Also, uncertainty is often nonlinear and time-varying. In the proceeding work, we proposed a class of robust control of a robot manipulator and provided the stability analysis. In the work, we propose a class of adaptive robust control of robot manipulator with bound estimation. Through experiments, the proposed adaptive robust control scheme is proved to be an efficient control technique for real-time control of a robot system using DSP.

• 한국군사과학기술학회지
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• 제10권2호
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• pp.38-46
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• 2007

This paper proposes a design method of a CDU(Control Display Unit) for commercial INS(Inertial Navigation Systems). In order to guarantee reusability and extendability, the design method is based on the class programming of the Windows operating system. Since the CDU has abstracted functions and variables, it can be interfaced with any INS. It is also easy to extend the designed functions using inheritance and polymorphism of the class. In order to show usefulness of the CDU, it has been implemented for the H-726 INS.