• 한국세라믹학회지
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• 제36권6호
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• pp.655-661
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• 1999

${\beta}$-SiC formation mechanism in Si melt-C-SiC system with varying in size of carbon source was investigated. A continuous reaction sintering process using Si melt infiltration method was adopted to control the reaction sintering time effectively. It was found that ${\beta}$-SiC formation mechanism in Si melt-C-SiC system was directly affected by the size of carbon source. In the Si melt-C-SiC system with large carbon source ${\beta}$-SiC formation mechanism could be divided into two stages depending on the reaction sintering time: in early stage of reaction sintering carbon dissolution in Si melt and precipitation of ${\beta}$-SiC was occurred preferentially and then SIC nucleation and growth was controlled by diffusion of carbon throughy the ${\beta}$-SiC layer formed on graphite particle. Furthmore a dissolution rate of graphite particles in Si melt could be accelerated by the infiltration of Si melt through basal plane of graphite crystalline.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.117.5-117
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• 2001

This paper presents the key idea of handlebar reaction force and pedal resistance force generation in creating life-like feeling in KAIST bicycle simulator. Also, it provides methods to evaluate its reality level with given reaction force profile. In KAIST bicycle simulator, the pedal resistance force and the handlebar reaction force are calculated using the bicycle dynamic model. With the information handlebar angle, rider´s pedaling torque and road profile transmitted from the handlebar system, the pedal system and the visual part, the bicycle dynamics engine calculates the handlebar reaction force and the pedal velocity. The handlebar system and the pedal resistance system generate reaction force and resistance force transmitted from dynamics engine. However to make more realistic riding feeling ...

• 한국분말재료학회지
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• 제10권5호
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• pp.349-352
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• 2003

This study examined the correlation of various operational factors including reaction temperature and the quantity of reductant and diluent with the characteristics of powder using $K_2$ TaF$_{7}$ as feed materials, Na as a reductant and KCl/KF as a diluent. Also to control the particle size and shape, external supply system developed, it can provide a feed material and a reductant at a fixed quantity and evaluated the characteristics of tantalum powder. When the external supply system was applied instead of the batch type process that charges feed material, reductant and diluent at the same time, it was possible to induce regular reduction reaction between feed material and reductant, which increased the recovery rate and reduced the mixture of impurities. In particular, the application of the external supply system enabled the control of reaction temperature and reaction speed according to the feeding rate of feed material during reduced reaction, and resultantly it enabled the manufacturing of granular-shaped powder with a regular granularity of 2∼3 ${\mu}{\textrm}{m}$ and purity of 99.5%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2986-2988
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• 1999

This paper presents a new concept to implement and to control of tactile reproduction simulator by implementation of compliance emulator system. Compliance emulator system is a kind of levitation system using magnetic force. In the compliance emulator system, a floated plate moves vertically. When an external force is applied to the plate, the system produces a controlled reaction force by using 6 electromagnet. For the control, a LVDT displacement sensor and PD control method is used.

• 대한간호학회지
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• 제27권4호
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• pp.912-922
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• 1997

The purpose of this study was to examine the effect of supportive nursing on stress reaction of breast cancer patients undergoing chemotherapy. The nonequivalent control group pre-test/post-test design was used for this experimental study. The subjects were 32 patients who were receiving chemotherapy after mastectomies at K hospital in Taegu from June, 1994 to June 1995. Among 32 subjects, 16 were placed in the experimental group and 16 in the control group. The experimental and control groups were tested for general characteristics, trait anxiety, health locus of control, family support, state anxiety, hopelessness, physical stress, and anxiety behavior. Collected data was analized by means of a chisquare test and a t-test for the comparative analysis of the general characteristics and homogeneity of subjects. ANOVA, and MANOVA were used for testing the hypothesis. Reliability of the tools were analyzed using the Pearson Correlation coefficient. The results of this study were as follows : 1. The hypothesis : The stress reaction of the experimental group which took supportive nursing was lower than the stress reaction of the control group : this was supported statistically. The main variable influenced in stress reaction was hopelessness. Supportive nursing for breast cancer patients, who are receiving chemotherapy, was especially effective in the reduction of hopelessness compared to state anxiety, physical stress, and anxiety behavior. 2. An analysis of the difference on stress reaction, according to the frequency of supportive nursing between the control and experimental group, showed the level of hopelessness of the experimental group was lower than the control group after four supportive meeting sessions. But there was no statistical difference in state anxiety, physical stress, and anxiety behavior. In conclusion, this study supported utilization of supportive care as well as demonstrating the effectiveness of the System-Developmental Stress Model developed by Chrisman and Riehl-Sisca.

• 항공우주기술
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• 제12권1호
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• pp.189-199
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• 2013

본 논문에서는 나로호 3차 비행시험에서의 2단 자세제어 결과를 정리하였다. 나로호 2단 추력기시스템에 의한 무추력 비행구간 3축 자세제어 및 추력벡터제어에 의한 킥모터 연소구간 피치/요 자세제어가 정상적으로 수행되었음을 보였다. 무게중심 오프셋, 킥모터 슬래그 영향, 킥모터 잔류추력 영향으로 인한 외란에도 불구하고 2단 자세제어기가 모든 비행구간에서 성공적으로 작동하였음을 보였다. 이러한 결과들은 국내의 발사체 자세제어 기술을 향상시키는 데 있어서 중요한 토대를 마련할 것이다.

• 항공우주기술
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• 제11권1호
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• pp.145-157
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• 2012

상평면상에서 추력기를 사용하는 자세제어 시스템의 리밋 사이클을 해석하는 새로운 기법이 논문에 의해서 제안되었다. 그러나 이것은 소프트 시뮬레이션상에서 Haloulakos 방식보다 제안 방식이 정확함을 보였지만, 실제 시스템으로 검증하지는 못하였다. 그래서 저자의 제안 방식을 KSLV-I 추력기 자세제어 시스템에 대한 실시간 모의시험으로 검증하고, 리밋 사이클 해석에 대하여 실시간 모의시험 결과와 이론적으로 구한 값을 비교/분석하였다.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.311-317
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• 2011

Momentum changing actuators like reaction wheels and control moment gyros are generally used for spacecraft attitude control. This type of actuators produces force and torque disturbances. These disturbances must be reduced since they degrade the quality of spacecraft attitude control. Major disturbances are mainly due to static and dynamic imbalances. This paper gives attention to the reduction of the static and dynamic imbalance. Force/torque measurement system is used to measure the disturbance of the test reaction wheel. An identification method for the location and magnitude of the imbalance is suggested, and the corrections of the imbalance are performed using balancing method. Through balancing, the static and dynamic imbalance is remarkably reduced.

• Journal of applied mathematics & informatics
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• 제6권1호
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• pp.127-142
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• 1999

This paper develops a methematical model for growth and exploitation of a schooling fish species using a realistic catch-rate function and imposing a tax on the catch to control harvesting. Fishing effort is assumed to depend on the net revenue. The steady states of the system are determined and their local and global stabil-ity are discussed. Taking the tax as a control variable; the optimal harvest policy is formulated and solved as a control problem. The results are illustrated with the help of a numerical example.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.