• 대한인간공학회지
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• 제22권1호
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• pp.31-42
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• 2003

This study describes a modification of the technique for human error analysis in nuclear power plants (NPPs) which adopts advanced Man-Machine Interface (MMI) features based on computerized working environment, such as LCOs. Flat Panels. Large Wall Board, and computerized procedures. Firstly, the state of the art on human error analysis methods and efforts were briefly reviewed. Human error analysis method applied to NPP design has been THERP and ASEP mainly utilizing Swain's HRA handbook, which has not been facilitated enough to put the varied characteristics of MMI into HRA process. The basic concepts on human errors and the system safety approach were revisited, and adopted the process of FMEA with the new definition of Error Segment (ESJ. A modified human error analysis process was suggested. Then, the suggested method was applied to the failure of manual pump actuation through LCD touch screen in loss of feed water event in order to verify the applicability of the proposed method in practices. The example showed that the method become more facilitated to consider the concerns of the introduction of advanced MMI devices, and to integrate human error analysis process not only into HRA/PRA but also into the MMI and interface design. Finally, the possible extensions and further efforts required to obtain the applicability of the suggested method were discussed.

• 제어로봇시스템학회논문지
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• 제17권9호
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• pp.922-931
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• 2011

An efficient calibration algorithm for mobile robot localization using infrared range finder is proposed. A calibration is important to guarantee the performance of other algorithms which use sensor data because it is pre-process. We experimentally found that the infrared range finder PBS-03JN has error characteristics depending on both distance and scan angle. After obtaining 2-D grid error characteristic data on distance and scan angle, we proposed a simple and efficient calibration algorithm with a 2-D piecewise linear function set. The performance of our proposed calibration algorithm is verified by experiments and simulation.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1349-1359
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• 2016

Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX ($T_{co}$) and the hot outlet temperature of the intermediate heat exchanger ($T_{ho2}$) by manipulating the hot-side flow rates of the heat exchangers ($F_h/F_{h2}$) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX ($T_{co}$) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.

• 한국항공우주학회지
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• 제47권4호
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• pp.289-299
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• 2019

자세제어 M&S(Modeling & Simulation)는 모델링 정밀도에 따라 간단한 자세제어 알고리즘 설계부터 실제 탑재 소프트웨어 검증까지 활용될 수 있다. 본 논문은 CMG 기반 위성 자세제어를 위한 M&S 소프트웨어를 소개한다. 개발된 소프트웨어는 크게 6자유도 모델링과 자세제어 알고리즘으로 나뉠 수 있다. 6자유도 모델링은 CMG 구동기 모델링과 우주환경 모델링(궤도외란/자세외란)을 포함한다. 자세제어 알고리즘은 CMG 모터속도 제어기(내부루프)부터 토크명령생성 및 스티어링 법칙(외부루프)을 포함한다. M&S는 하위 레벨인 CMG 모터제어부터 상위 레벨인 지구관측임무 수행까지 단계적으로 수행되며, 적용 레벨에 따라 3개 모듈로 나뉜다. 본 M&S 소프트웨어는 초기 자세제어 알고리즘 개발을 목표로 개발되었는데, 향후 상세한 위성체/구동기 모델링 및 우주환경 모델링을 반영해 점차 활용 범위를 넓힐 수 있을 것으로 기대된다.

• Journal of Advanced Research in Ocean Engineering
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• 제2권4호
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• pp.192-201
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• 2016

This study examined a PD controller and its application to automatic berthing control of an unmanned surface vehicle (USV). First, a nonlinear mathematical model was established for the maneuvering of the USV in the presence of environmental forces. A PD control algorithm was then applied to control the rudder and propeller during an automatic berthing process. The algorithm consisted of two parts, namely the forward velocity control and heading angle control. The control algorithm was designed based on longitudinal and yaw dynamic models of the USV. The desired heading angle was obtained using the "line of sight" method. Finally, computer simulations of automatic USV berthing were performed to verify the proposed controller subjected to the influence of disturbance forces. The results of the simulation revealed a good performance of the developed berthing control system.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.135-135
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• 2003

The fast evolution in the fold of optical communication systems demands powerful optical information treatment. These functions can be performed by integrated optical systems. A key component of such systems is erbium doped waveguide amplifier(EDWA). The intra 4f radiative transition of Er at 1.5 $\mu\textrm{m}$ is particularly interesting because this wavelength is standard in optical telecommunications. The fabrication of waveguide amplifier for integrated optics using sol-gel process has received an increasing attention. Potential advantage of lower cost by less capital equipment and easy processing makes this process an attractive alternatives to conventional technologies like flame hydrolysis deposition, ion exchange and chemical vapor deposition, etc. In addition, sol-gel process has been found to be extremely suitable for the control of composition and refractive index related directly with optical properties. The main drawback of such an amplifier with respect to the EDWA is the need for a much higher Er3+ concentration to compensate for the smaller interaction length. However, the high doping of Er might be resulted in the non-radiative relaxation by clustering of Er ions End co-operative upconversion. In order to solve this problem, we investigate the possibility of avoiding short Er-Er distances by encapsulation of Er3+ ions in hosts such as organic-inorganic hybrid materials. For inorganic-organic hybrid sols, methacryloxypropyltrimethoxysilane (MPTS), zirconyl chloride octahydrate and erbium(III) chloride hexahydrate were used as starting materials, followed by conventional sol-gel process. It was observed by TEM that nano sols having core/shell toplology were formed, depending on the mole ratio of Zr/Er. The surface roughness for the coatings on Si substrate was investigated by AFM as a function of Zr/Er ratio. The local environment and vibrational Properties of Er3+ ions were studied using Near-IR, FT-IR, and UV/Vis spectroscopy. Nano hybrid coatings derived from polymer and Er doped encapsulation Eave the good luminescence at 1.55$\mu\textrm{m}$.

• 한국항해항만학회지
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• 제36권8호
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• pp.643-649
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• 2012

본 연구에서는 크루즈선에서 발생하는 오 폐수의 고도처리를 위하여 SBR공정에 유효미생물을 주입하는 변법을 이용하여 실험실 규모의 실험을 수행하였다. 질소 인의 고도 처리 효율과 크루즈선이라는 특수 환경과의 접목성을 검토한 결과 SBR공정에 유효미생물을 주입하는 변법은 선박환경에 매우 적합한 것으로 평가되었다. 또한 기존의 활성슬러지에 유효미생물의 주입함으로써 슬러지 팽화 등의 문제를 해결할 수 있어 슬러지의 안정성을 확보할 수 있었으며, 미생물 관찰 결과 고도처리에 유리한 미생물종의 출현으로 질소 인의 처리 효율이 높아지는 것을 확인할 수 있었다. 이로 인해 총질소와 인의 제거 효율은 74%, 75%로 나타났으며 이러한 결과로 미루어 강화되어가는 해양오염기준을 충만족시킬 수 있을 공정으로 판단된다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제17권2호
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• pp.109-129
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• 1995

Many patients with malignancies of the head and neck undergo radiation therapy, either as the only method of treatment or in combination with surgery. Radiation therapy has great effect in the case of fairly advanced malignancies which can't be operated radically. But the complication of radiation therapy arise because of damage to the peri- and operated area. It is fully known that irradiated tissue shows retarded healing process in the skin, mucosa and especially vascuslar tissue. The purpose of this study was to observe the healing process of irradiated free or island flap after operation. As Experimental Models, Femoral arterial and venous anastomosis (Group 1), Epigastric-island flap (Group 2) and free Epigastric falp(Group 3) with irradiated postoperative 24 hrs were made on 30 rats/group. As Control Model(Group 4), Free Epigastric flap was not irradiated after operation was chosen on 30 rats. The amount of irradiation was single fraction of 20 Gy using as linear megavoltage accelerator. Difference between Experimental and Control group was evaluated by the method of clinical examination, histopatholoical findings, biochemical analysis and DNA activity at postoperative 1, 3, 7, 14 and 28 days. The results were as follows, 1. Skin color and new epithelization in group 2 and 3 was similar to control group clinically. 2. Postoperarive patency of femoral artery and vien showed 5% and 22% of ischemity. 3. The externa, media and intima of irradiated femoral artery and vein were similar to control group histopathlogically. 4. Granulation and collagen tissue accumulation of irradiated groups were more active due to degenerative and fibrotic changes than control group at postoperative 7 days histopathologically. 5. The hydroxyproline content of all experimental groups were reduced till 14 days and the group 2 was most prominent at postoperative 7 and 28 days(p<0.05). 6. DNA activities of all groups were reduced till 3 days, but begun to recover at 7 days and more activities in control group than irradiated group(p<0.05). Based on the above results, the clinical healing process of free flaps with irradiated postoperative 24 hrs little difference from control group without complications.

• International Journal of Advanced Culture Technology
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• 제12권1호
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• pp.293-298
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• 2024

The purpose of an internal control system is to prevent the occurrence of errors and fraud in the process of producing accounting information, thereby providing investors with reliable information. For the effective operation of an internal control system, it is necessary to secure a sufficient number of personnel and experienced staff. This study focuses on the personnel directly involved in producing accounting information, examining whether companies that invest in their internal control staff experience a mitigation in the phenomenon of valuation errors. The analysis revealed that the size and experience months of the personnel responsible for internal control have a significant negative relationship with valuation errors. This result implies that by securing sufficient personnel for the smooth operation of the internal control system and placing experienced staff within the system, investors can effectively make judgments about the intrinsic value based on quality accounting information, thereby reducing valuation errors.

• 한국정밀공학회지
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• 제18권8호
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• pp.107-115
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• 2001

Drilling torque was measured indirectly using the spindle motor current and controlled in real time through feedrate manipulation in a machining center. The PID controller designed in the previous paper was applied to drilling torque control. A series of cutting experiments were performed for various cutting conditions. Experimental results showed that the drilling torque was well regulated at a given reference level by feedrate manipulation in all cutting conditions. The increase in the cutting torque and temperature according to the increase in machining depth was suppressed and the risk of the drill failure and the drill flank wear were reduced remarkably through cutting torque control. Moreover, the suggested cutting torque control system doesn\`t disturb the cutting process and is practical for industrial environment. Therefore, the proposed culling torque control system will contribute to productivity improvement in drilling process.