• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.1212-1217
• /
• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• 한국수소및신에너지학회논문집
• /
• 제15권4호
• /
• pp.257-265
• /
• 2004

Numerical analysis, as EAM(Embedded Atom Method), in the atomic level is necessary to analyze the relation between the hydrogen and hydrogen absorption metals. EAM established on density functional theory was developed as a new means for calculating various properties and phenomena of realistic metal systems. In this study, we had constructed the EAM program from constitutive formulae and parameters of the hydrogen, nickel and palladium for the purpose of predicting the expansion behavior on hydrogen absorbing. In result, not only the ground state properties of metals but also lattice constants and the volume expansion ratio of metal hydrides show good agreement with Daw's data and experiment data.

• 한국통신학회논문지
• /
• 제23권9A호
• /
• pp.2305-2312
• /
• 1998

본 논문에서는 Virtual Cellular Network(VCN)을 사용하는 무선 통신망에서 음성 패킷의 지연 특성을 분석하였다. 주기적으로 발생하는 음성 패킷이 슬롯-알로하 프로토콜로 전송될 때의 전송 특성을 Markov Chain으로 모델링하여 정상 상태(steady state)에서의 지연 확률 분포를 구하였고, 무선 채널의 평균 수신확률(prbability of capture), 재전송 방식 등이 성능에 미치는 영향을 분석하였다. 이를 위하여 무선 단말기의 수신 확률의 변화에 따른 음성 패킷의 전송 지연 누적 확률 함수를 구하였다. 재전송 방식의 평균 backoff 시간이 성능에 미치는 영향을 알아보기 위해 음성 패킷 발생 주기(N 슬롯시간)당 평균 재전송 횟수, NPr을 파라미터로 정의하였으며 여러가지의 프레임 크기 N에 대하여 1% outage delay를 비교하였다. 성능 실험 결과 NPr의 최적의 범위는 4~7임을 알 수 있었다. 따라서 프레임 크기 N이 주어졌을 때의 재전송 시도 확률 Pr을 구할 수 있다. 또한 전송큐의 크기가 유한함으로써 발생하는 blocking 확률과 전송큐의 적절한 크기를 구하였다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 추계학술대회 논문집
• /
• pp.32-36
• /
• 2004

In order to achieve high performance vector control, it is essential to measure accurate ac current. The errors generated from current path are inevitable, and they could be divided into two categories: offset error and scaling error. The current data including these errors cause periodic speed ripples which are one and two times of stator electrical frequency respectively. Since these undesirable ripples bring about bad influences to motor driving system, a compensation algorithm must be needed in the control algorithm of the motor drive. In this paper, a new compensation algorithm is proposed. The signal of the integrator output of the d-axis current regulator is chosen and processed to compensate the current measurement errors. The compensation of the current measurement errors is easily implemented to smooth the signal of the integrator output of the d-axis current regulator by subtracting the DC offset value or rescaling the gain of the hall sensor. Therefore, the proposed algorithm has several features: the robustness of the variation of the mechanical parameters, the application of the steady and transient state, the easy implementation, and less computation time.

• 사상체질의학회지
• /
• 제16권3호
• /
• pp.25-33
• /
• 2004

1. Objectives Theoretically Healthy Condition of four constitution is based on intact state of four fundamental factors - digestion, urination, perspiration, defecation. Each one of these four factors is specifically related to its respective constitution. We made SHI(Sasangin Health Index) 10 items from four factors, and examined clinical efficacy of the four factors as index of health status in four constitution. 2. Methods and Procedures We offered QSCCII, SHI and SF-36 questionnaires to adults who had a periodic medical examination. 233 adults were classified to one of four constitution. We compared means of 8 scale scores of SF-36, and computed the correlation coefficient between 8 scale scores of SF-36 and 10 item scores of SHI in four constitution. 3. Results In Soyangin, stool volume and frequency are weakly correlated with health status(P<0.05). In Soeumin, appetite is weakly correlated with health status(P<0.05). In Taeumin, there is no correlation between perspiration and health status. 4. Conclusions 2 factors - digestion, defecation - had clinical efficacy as index of health status.

• 설비공학논문집
• /
• 제22권11호
• /
• pp.767-772
• /
• 2010

The incompressible viscous flow past a sphere under forced oscillation is numerically investigated at a Reynolds number of 300. The immersed boundary method is used to handle the sphere oscillating vertically to the streamwise direction. There are two important variables to characterize the oscillating state of a sphere. One is an oscillating amplitude normalized by the sphere diameter is set as a fixed number of 0.2. Another is the frequency ratio which is defined by $f_e/f_o$, where fe and fo are the excited frequency and the natural frequency of vortex shedding for the stationary sphere. In this study, three different frequency ratios of 0.8, 1.0 and 1.2 are considered. The results show a periodic flow with hairpin vortices shedding from upper and lower positions as well as vortical legs obliquely extended by oscillating motion of sphere. The enveloping vortical structure experience rupture twice in one period of oscillation. As the frequency of oscillation is increased, the vortical legs are getting shorter and eventually the hairpin vortices are much closer to the adjacent one.

• 한국임상약학회지
• /
• 제10권1호
• /
• pp.7-12
• /
• 2000

This study is intended to provide information to menopausal women so they can control their symptoms. The basic data was gathered by interviewed 200 postmenopausal women on a HRT program. The women were questioned about their perception of menopause and compliance to the therapy with the fellowing result $71.7\%$ of the women experianced hot flushes, and $64.1\%$ experienced short term memory loss and some psychological symptoms. The women reported that these symptoms reduced their quality of life. $53\%$ of the women responded that menopause is a natural state and $59.1\%$ agreed to HRT based on their doctor's recommendation. $76.2\%$ of the women reported that HRT was effective, with $74.7\%$ reporting reduced hot flush symptoms $67.3\%$ of the women reported compliance with the medication schedule. and $43.9\%$ reported periodic non-compliance. Although HRT has been shown to be an effective treatment, the study found that less than $10\%$ of postmenopausal women are currently being treated and these treated women are generally negligent in continuing with HRT, The study recommends that a program be developed that explains the benefits and risks of HRT to be distributed to patients being treated by doctors and pharmacists. In conclusions, It is very important for hormone replacement therapy on menopausal women to take more intensive medication consultation to increase medication compliance and effectiveness of pharmacotherapy.

• 설비공학논문집
• /
• 제7권4호
• /
• pp.622-632
• /
• 1995

The present numerical study is aimed to investigate time-dependent characteristics of a two-dimensional lid-driven square cavity flow of three high Reynolds numbers, $7.5{\times}10^3$, $10^4$ and $3{\times}10^4$. A conservative convection term on irregular grids was adopted by renewing the MAC type difference schemes on regular grids. Relaxation of velocity and pressure is implemented by SOLA algorithm. In case of $Re=7.5{\times}10^3$, flow behavior converges to steady state after a transient period. But for $Re=10^4$, periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found and continuous movements of small eddies in the secondary flow regions are also discovered. Random generation of eddies and their active migrating behavior are detected for $Re=3{\times}10^4$, resulting in complete unsteady and non-linear flow characteristics. And, an organized structure similar to a Moffat vortex is also observed from the time-mean flow patterns. Furthermore, a typoon-like vortex(TLV) appears intemittently and rotates along the separation regions and boundary layers.

• 동아시아식생활학회지
• /
• 제15권2호
• /
• pp.152-157
• /
• 2005

The purpose of this study was to investigate dietary habit and to evaluate nutritional status and obesity index about adults living in Daejon area. This study was conducted with 250 subjects (male 130, female 120) who visited periodically a periodic health center in a general hospital from May to June in 2002. Questionaries were used for studying of dietary habit and food frequency method. Dietary intake was assessed by food frequency method and consumption of foods and nutrients was analyzed. The relationship between dietary habit and obesity were also analyzed. Dietary habit was better in female than mail. There was no significant difference in mean of Broca's index between female ($110.6\pm16.6\%$) and male ($110.0\pm13.7\%$). The obesity group showed low dietary habit score in irregular eating behavior, frequent eating out and over-intake of salty foods. Especially mean intakes of energy were lower than Korean RDA in all groups. All groups except obesity group were deficiency of vitamin A and vitamin $B_{1}$ and calcium.

• Journal of Power Electronics
• /
• 제13권3호
• /
• pp.419-428
• /
• 2013

The modular multilevel cascade converter (MMCC) is a new family of multilevel power converters with modular realization and a cascaded pattern for submodules. The MMCC family can be classified by basic configurations and submodule types. One member of this family, the Hexverter, is configured as Double-Delta Full-Bridge (DDFB). It is a novel multilevel AC/AC converter with direct power conversion and comparatively fewer required components. It is appropriate for connecting two three-phase systems with different frequencies and driving an AC motor directly from a utility grid. This paper presents the dq model of a Hexverter with both of its AC systems by state-space representation, which then simplifies the continuous time-varying model into a periodic discrete time-invariant one. Then a generalized multivariable optimal control strategy for regulating the Hexverter's independent currents is developed. The resulting control structure can be adapted to other MMCCs and is flexible enough to include other control criterion while guaranteeing the original controller performance. The modeling method and control design are verified by simulation results.