• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
• /
• pp.641-646
• /
• 1998

In order to enhance the dynamic and interactive simulation capability of a system thermal hydraulic code for nuclear power plant, applicability of flow network models in SINDA/FLUIN $T^{™}$ has been tested by modeling feedwater system and coupling to DSNP which is one of a system thermal hydraulic simulation code for a pressurized heavy water reactor. The feedwater system is selected since it is one of the most important balance of plant systems with a potential to greatly affect the behavior of nuclear steam supply system. The flow network model of this feedwater system consists of condenser, condensate pumps, low and high pressure heaters, deaerator, feedwater pumps, and control valves. This complicated flow network is modeled and coupled to DSNP and it is tested for several normal and abnormal transient conditions such turbine load maneuvering, turbine trip, and loss of class IV power. The results show reasonable behavior of the coupled code and also gives a good dynamic and interactive simulation capabilities for the several mild transient conditions. It has been found that coupling system thermal hydraulic code with a flow network code is a proper way of upgrading simulation capability of DSNP to mature nuclear plant analyzer (NPA).

• 과학기술학연구
• /
• 제3권2호
• /
• pp.61-82
• /
• 2003

급격한 기술변화와 새로운 산업의 출현과정에서 기업은 현재의 능력을 바탕으로 새로운 능력을 구축하여 환경변화에 적응한다. 기업 능력의 진화과정에 대한 연구는 이러한 과정에서 기업이 가지는 본질과 특성이 산업간 경계를 넘어 어떻게 발생하는지 설명할 수 있으며, 이를 통해 기업이 잠재적인 미래 산업에서 가지는 차별성과 경쟁우위의 근원이 무엇인지 알 수 있다. 본 논문에서는 기존 문헌에 대한 고찰을 통해 새로운 산업에 참여하는 기업의 차별성이 어떤 요소에 의해 발생하고, 각 요소의 영향은 시간의 흐름에 따라 어떻게 변화하는지를 살펴보고자 한다.

• 패션비즈니스
• /
• 제25권1호
• /
• pp.39-50
• /
• 2021

The purpose of this study was to investigate how wearing calf support and applying of electronic muscle simulation(EMS) affected the ability to balance. In this study, the one leg standing test for static balance and the Y balance test for dynamic balance were used to assess balance. At this time, the pressure of the calf support was different to produce two supporters, and a difference between wearing the support before, after, and after applying EMS was evaluated. Seven men in their 20s with healthy bodies were measured five times each with a five-minute break, taking into account muscle fatigue, and the difference between each variable was analyzed through a follow-up test using nonparametric statistical analysis. Studies have shown more difference from supporter B with a more appropriate pressure (mmgh) for increasing balance capability than from supporter A. In addition, it was confirmed that the use of EMS electrostimulation and support before measuring the balance capability resulted in a greater difference. The proper pressure (mmgh) supporters and EMS can increase the ability to balance, and these results can be expected to improve the balance ability of ordinary people in their daily lives.

• Journal of Power Electronics
• /
• 제12권1호
• /
• pp.145-156
• /
• 2012

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

• Structural Engineering and Mechanics
• /
• 제49권5호
• /
• pp.619-629
• /
• 2014

As hyperboloidal cooling towers (HCTs) growing larger and slender, they become more sensitive to gust wind. To improve the dynamic properties of HCTs and to improve the wind resistance capability, stiffening rings have been studied and applied. Although there have been some findings, the influence mechanism of stiffening rings on the dynamic properties is still not fully understood. Based on some fundamental perceptions on the dynamic properties of HCTs and free ring structures, a concept named "participation degree" of stiffening rings was proposed and the influence mechanism on the dynamic properties was illustrated. The "participation degree" is determined by the modal deform amplitude and latitude wave number of stiffening rings. Larger modal deform amplitude and more latitude waves can both result in higher participation degree and more improvement to eigenfrequencies. Also, this concept can explain and associate the pre-existing independent findings.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제50권1호
• /
• pp.13-25
• /
• 2011

The Goals of mathematics education for the lower grades of primary school is to shape the basic concepts and the skills of mathematics. To achieve this goal, it is necessary an assessment which is able to help the students' learning activities by precisely diagnosing their basic mathematical capability. It should lend the students an assistance in diagnosing and revising their problems throughout teacher's cognitive participation in the process of mathematical problem solving. I would like to suggest the dynamic assessment as one of these kinds of approaches. In order to prove the utilities of this way, it was examined the necessity of dynamic assessment on the basis of the Vygotsky's theory after looking into the characteristics of the contents and methods of the mathematics education for the lower grades of primary school. Next, I researched the principles of the dynamic assessment and embodied the assessment tool to evaluate the mathematical achievement of the lower grades of the primary school. Lastly, it was provided the examples of the dynamic assessment tool in order to assist the practice of it.

• International Journal of Contents
• /
• 제6권1호
• /
• pp.47-52
• /
• 2010

Skyline queries are an important new search capability for multi-dimensional databases. Most of the previous works have focused on processing skyline queries over static data set. However, most of the real applications deal with the dynamic data set. Since dynamic data set constantly changes as time passes, the continuous skyline computation over dynamic data set becomes ever more complicated. In this paper, we propose a multiple layer grids method for continuous skyline computation (MLGCS) that maintains multiple layer grids to manage the dynamic data set. The proposed method divides the work space into multiple layer grids and creates the skyline influence region in the grid of each layer. In the continuous environment, the continuous skyline queries are only handled when the updating data points are in the skyline influence region of each layer grid. Experiments based on various data distributions show that our proposed method outperforms the existing methods.

• 컴퓨터교육학회논문지
• /
• 제4권1호
• /
• pp.99-107
• /
• 2001

수학교육에서 기하교육의 주된 목적 중 하나는 기하학적 직관능력과 그것을 바탕으로 한 논리적인 추론능력을 향상시키는 것이다. 직관과 관련된 시각적인 요소는 기하의 교수학습에서 중요한 역할을 한다. 따라서, 본 연구는 시각적 요소에 대한 동적인 조작이 가능한 멀티미디어 타이틀을 개발하고 그 효과를 검증하는데 목적이 있다. 중학교 3학년 과정의 "피타고라스의 정리 및 그 활용"을 학습하기 위한 본 타이틀은 Toolbook으로 설계 및 구현하였으며 개별학습이 가능하고 학교 현장에 적용할 수 있다. 그리고 중학교 2학년을 대상으로 적용집단과 비교집단으로 구분하여 수업을 실시하고 학업성취도 평가와 설문조사를 실시하였다. 두 집단의 학업성취도를 SPSS를 사용하여 t-test를 실시한 결과 적용집단이 비교집단에 비하여 학업성취도가 높은 것으로 나타났으며, 시각적인 요소에 대한 동적인 조작 가능성의 제공은 학습자에게 매우 높은 학습효과를 지각하게 하고 지적 능력 향상에 도움이 되는 것으로 나타났다.

• 아동학회지
• /
• 제29권1호
• /
• pp.339-353
• /
• 2008

This study examined how cognitive style in young children affects mathematical problem-solving performance. Findings showed that the types of patterns presented were linked to the degree of difficulty of the tasks and that disparity between field-independent and field-dependent in cognitive style was broader when subjects worked with more complicated pattern problems. Subjects' marks varied by cognitive style when dynamic assessment was conducted, but cognitive style made no difference in their mathematical learning capability. Cognitive style had an impact not only on the task performance of the learners but on the extent to which they were in need of help during the problem-solving process. Yet, it exercised no influence on how much progress the subjects made when fully assisted.

• ETRI Journal
• /
• 제25권1호
• /
• pp.25-33
• /
• 2003

This paper describes interactive dynamic simulation schemes for articulated bodies in virtual environments, where user interaction is allowed through a haptic interface. We incorporated these schemes into our dynamic simulator I-GMS, which was developed in an object-oriented framework for simulating motions of free bodies and complex linkages, such as those needed for robotic systems or human body simulation. User interaction is achieved by performing push and pull operations with the PHANToM haptic device, which runs as an integrated part of I-GMS. We use both forward and inverse dynamics of articulated bodies for the haptic interaction by the push and pull operations, respectively. We demonstrate the user-interaction capability of I-GMS through on-line editing of trajectories for 6-dof (degrees of freedom) articulated bodies.