• Radiation Oncology Journal
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• 제22권4호
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• pp.316-324
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• 2004

목적 : 간 등의 상 복부에 위치한 종양의 방사선 조사 체적은 호흡에 의한 종양의 이동을 포함하기 때문에 방사선 조사 체적이 증가되어 방사선 독성 및 정상조직 선량이 증가하게 된다. 이러한 문제점을 극복하기 위해 동 팬텀과 초음파센서를 이용하여 호흡운동에 의한 환자 체표면의 움직임을 획득하고, 획득한 데이터의 역 값을 이용해 환자침대를 조절해줄 수 있는 호흡운동 조절 방사선치료 기술을 개발하고자 한다. 대상 및 방법 : 호흡운동에 의한 환자 체표면의 움직임을 평가하기 위해 제작한 팬텀은 조정기(BS II, 20 Mhz, 8K Byte), 센서(Ultra-Sonic, range $3\~3$ m), Computer (RS232C), Sewo Motor (Torque 2.3 Kg) 등으로 구성하였고, 제어와 구동을 위한 획득-보정-분석 프로그램을 작성하였다. 최대 2 cm 범위 내에서 팬텀을 움직이게 하였고, 팬텀의 움직임과 보정이 순차적으로 일어나도록 프로그램하였으며, x, y, z가 연속적으로 움직이도록 구성하였다. 임의의 움직임 데이터(유격이 2 cm이 되도록 하여 3차원 데이터 형태)를 입력하여 동 팬텀을 조정하고, 동시에 팬텀 움직임을 초음파 센서를 이용하여 획득한 후, 두 데이터간의 비교, 분석을 시행하였다. 이후 쥐(Guinea-pig, about 500g)를 이용하여 호흡운동에 의한 환자 체표면의 움직임을 획득한 후 획득한 데이터의 역 값으로 팬텀을 구동시킴으로써 실시간 호흡운동 조절 방사선치료 기술을 평가하였다. 결과 : 팬텀 실험에서 3 차원 입력데이터에 대한 팬텀 보정 데이터간의 정확성을 시간에 대한 거리 값으로 비교한 결과 ${\pm}1\%$ 이내의 정확성을 알 수 있었고, 이에 필요한 보정시간은 $2.34{times}10^{-4}$초임을 알 수 있었다. 또한 동물 실험에서도 동일한 방법으로 시간에 대한 거리 그래프와 획득-보정간의 지연 시간 등을 분석한 결과 팬텀 데이터와 같은 결과를 얻을 수 있었다. 결론 : 팬텀, 동물 실험 모두에서 시간에 대한 거리 값과 각각의 경우에 획득-보정간의 지연 시간을 분석한 결과 데이터 값은 ${\pm}1\%$ 이내에서 일치하였으며, 데이터 획득-보정 지연 시간은 2.34H10-4 초 이내 즉, 실시간으로 얻을 수 있어 새로운 호흡운동 조절 방사선치료 기술의 임상적용에의 가능성을 확인할 수 있었다.

• 에너지공학
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• 제17권1호
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• pp.31-37
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• 2008

현재 에너지 효율프로그램에 대한 수요관리 목표량과 투자비는 과거 실적 데이터를 바탕으로 단일한 Bass 확산 모형을 이용하여 산정되고 있다. 국내외적으로 제품 등의 보급량 예측에 널리 사용되는 Bass 확산 모형은 시간과 세 가지 계수들에 대한 함수로 표현되며, 계수들의 추정에 있어서 제품의 과거 실적 데이터의 충분한 확보가 필수적이다. 국내의 경우 에너지 효율 측면에서 고효율기기의 수요관리 목표량 산정을 위해 기기별 보급량 예측이 선행되어야 하며, 기기별 보급량 예측은 Bass 모형을 근간으로 하고 있다. 그러나 현재 진행 중인 고효율기기 보급 프로그램의 조명기기, 인버터, 자판기와 전동기는 그 진행이 길지 않아 Bass 확산 모형을 이용한 보급량 예측에 필수요건인 충분한 실적 데이터가 존재하지 않은 실정이다. 이는 기기의 미래 보급량 예측에 큰 오차가 발생할 수 있으며 보급 예측량에 대한 정확성을 기대하기 어려우므로 앞으로의 고효율기기의 보급 예측의 방식에 제도적 개선이 필요한 상황이라 할 수 있다. 본 논문에서는 Bass, virtual Bass, Logistic과 Lawrence & Lawton 확산 모형을 이용하여 각 고효율 기기의 미래 보급 확산 추이를 살펴보았다. 또한 기기별 특성에 따른 모형 선호도 평가를 위해 통계랑 기준에 근거하여 실적 데이터와의 오차 범위를 산정하였다. 이 결과를 바탕으로 각 확산 모형을 이용한 기기 보급량 예측에 있어서 확산 모형의 단순 적용에 따른 오차 발생 원인과 기기별 특성에 따른 확산 모형 선호도를 분석하였다.

• 한국해양공학회지
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• 제34권5호
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• pp.294-303
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• 2020

This study discusses data collection, calculation of wind and wave-induced resistance, and speed-power analysis of an 8,600 TEU container ship. Data acquisition system of the ship operator was improved to obtain the data necessary for the analysis, which was accomplished using SPA (Ship Performance Analysis, Park et al., 2019) in conformation with ISO15016:2015. From a previous operation profile of the container, the standard operating conditions of mean draft were 12.5 m and 13.6 m, which were defined with the mean stowage configuration of each condition. Model tests, including the load-variation test, were conducted to validate new ship performance and for the speed-power analysis. The major part of the added resistance of container ship is due to the wind. To check the reliability of wind-resistance calculation results, the resistance coefficients, added resistance, and speed-power analysis results using the Fujiwara regression formula (ISO15016:2015) and Computational fluid dynamics (Ryu et al., 2016; Jeon et al., 2017) analysis were compared. Wind speed and direction measured using an anemometer were used for wind-resistance calculation and the wave resistance was calculated using the wave-height and direction-data from weather information. Also, measured water temperature was used to calculate the increase in resistance owing to the deviation in water density. As a result, the SPA analysis using measured data and weather information was proved to be valid and able to identify the ship's resistance propulsion performance. Even with little difference in the air-resistance coefficient value, both methods provide sufficient accuracy for speed-power analysis. The differences were unnoticeable when the speed-power analysis results using each method were compared. Also, speed-power analysis results of the 8,600 TEU container ship in two draft conditions show acceptable trends when compared with the model test results and are also able to show power increase owing to hull fouling and aging. Thus, results of speed-power analysis of the existing 8,600 TEU container ship using the SPA program appropriately exhibit the characteristics of speed-power performance in deal conditions.

• Steel and Composite Structures
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• 제35권6호
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• pp.789-798
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• 2020

The effect of Chitosan (CS), Carbon Nanotube (CNT) and hybrid (CS-CNT) fillers on the natural frequency of drilled composite plate is investigated by experimentally in this study. The numerical validation is also made with a program based on Finite Element Method (SolidWorks). Nine types filled and one neat composite plates are used in the study. The fillers ratios are 1% CS, 2% CS, 3% CS, 0.1% CNT, 0.2% CNT, 0.3% CNT, 1% CS+0.3% CNT, 2% CS+0.3% CNT, 3% CS+0.3% CNT. The specimens cut to certain sizes by water jet from the plates 400 mm × 400 mm in dimensions. Some of them are drilled in certain dimensions with drill. The natural frequency of each specimen is measured by the vibration test set up to determine the vibration characteristic. The vibration test set up includes an accelerometer, a current source power unit, a data acquisition card and a computer. A code is written in Matlab^® program for the signal processing. The study are investigated and discussed in four main points to understand the effect of the fillers on the natural frequency of the composite plate. These are the effect of fillers contents and amounts, orientation angles of fibers, holes numbers and holes sizes. As results, the natural frequency of the plate with 1% CS and 0.1% CNT hybrid filler is lower than those of the plates with other fillers ratios for 45° orientation angle. Besides, in the composite plate with 0° orientation angle, the natural frequency increases with increasing the filler ratio. Moreover, the natural frequency increases until a certain hole number and then it decreases. Furthermore, the natural frequency is not affected until a certain hole diameter but then it decreases.

• 한국간호교육학회지
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• 제16권2호
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• pp.213-221
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• 2010

Purpose: The purpose of this study was to investigate the perception of nursing student's preceptorship and to compare the perception on the readiness of clinical competence between nurse preceptors and senior-level nursing students. Method: Data was collected with self-administered questionnaires and analyzed by descriptive statistics and t-test. Study participants were 65 preceptors in one university hospital and 59 nursing students in the same university. Result: The knowledge and satisfaction about preceptorship in the nurse preceptor was 2.66 and 2.70 out of 5. Most of the preceptors (70%) agreed to the students preceptorship program even though the intention to be a preceptor was very low (14.1%). They responded that the merits of student preceptorship were self-development (29.7%) and knowledge acquisition (29.7%), whereas the disadvantages were increased workload (67.2%) and increased stress (23.4%). Requested rewards were monetary reward (44.4%) and promotion (33.3%). In all areas of clinical competence readiness, students' perception score was higher than preceptors'. Conclusion: Nursing education must reexamine current approaches to clinical teaching and seek methods to better prepare future nurses. These findings may serve as a guide to create an ideal students preceptorship program to place a greater emphasis on the competencies desired for providing high quality nursing services.

• 산업경영시스템학회지
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• 제43권4호
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• pp.161-167
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• 2020

In the process of cutting large aircraft parts, the tool may be abnormally worn or damaged due to various factors such as mechanical vibration, disturbances such as chips, and physical properties of the workpiece, which may result in deterioration of the surface quality of the workpiece. Because workpieces used for large aircrafts parts are expensive and require strict processing quality, a maintenance plan is required to minimize the deterioration of the workpiece quality that can be caused by unexpected abnormalities of the tool and take maintenance measures at an earlier stage that does not adversely affect the machining. In this paper, we propose a method to indirectly monitor the tool condition that can affect the machining quality of large aircraft parts through real-time monitoring of the current signal applied to the spindle motor during machining by comparing whether the monitored current shows an abnormal pattern during actual machining by using this as a reference pattern. First, 30 types of tools are used for machining large aircraft parts, and three tools with relatively frequent breakages among these tools were selected as monitoring targets by reflecting the opinions of processing experts in the field. Second, when creating the CNC machining program, the M code, which is a CNC auxiliary function, is inserted at the starting and ending positions of the tool to be monitored using the editing tool, so that monitoring start and end times can be notified. Third, the monitoring program was run with the M code signal notified from the CNC controller by using the DAQ (Data Acquisition) device, and the machine learning algorithms for detecting abnormality of the current signal received in real time could be used to determine whether there was an abnormality. Fourth, through the implementation of the prototype system, the feasibility of the method proposed in this paper was shown and verified through an actual example.

• 문화기술의 융합
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• 제8권2호
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• pp.23-28
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• 2022

본 논문은 우리나라 기업들의 성과에 대한 기업들의 고용, 인적자원개발, 노사관행의 시행이 미치는 영향력에 대하여 분석하였다. 분석을 위한 자료는 한국노동연구원(KLI)의 2017년 7회차 사업체패널 조사로 수집된 2,868개 기업에 대한 자료를 활용하였다. 기업의 성과는 전년도 영업이익을 대상으로 하였다. 고용은 신입사원의 공개채용여부, NCS직무능력에 대한 평가여부, 핵심인력 확보 프로그램 실행여부를 포함하였다. 인적자원개발은 재직자 훈련 실시여부, 직무능력향상도 평가여부, 저성과자 관리프로그램 시행 여부, 근로자 경력계획 여부, HRD에 직무분석 활용여부로 구성하였다. 노사관행에는 육아휴직 보장, 출산휴가에 대한 보장과 보육시설 지원 여부를 포함하였다. 분석방법은 영업이익의 흑자 및 적자 기업의 두 집단에 대한 이항 로지스틱 회귀분석을 사용하였다. 분석결과 기업의 성과에 대해 고용, 인적자원개발, 노사관행의 영향력을 확인할 수 있었으며, 기업 차원에서 성과를 높이기 위한 고용 및 인적자원 개발, 노사관행 관리의 시사점을 논의하였다.

• 비파괴검사학회지
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• 제9권1호
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• pp.30-38
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• 1989

Since the nuclear power plants in Korea have been operated in 1979, the nondestructive testing (NDT) of pressure vessels and/or piping welds plays an important role for maintaining the safety and integrity of the plants. Ultrasonic method is superior to the other NDT method in the viewpoint of the detectability of small flaw and accuracy to determine the locations, sizes, orientations, and shapes. As the service time of the nuclear power plants is increased, the radiation level from the components is getting higher. In order to get more quantitative and reliable results and secure the inspector from the exposure to high radiation level, automation of the ultrasonic equipments has been one of the important research and development(R & D) subject. In this research, it was attempted to visualize the shape of flaws presented inside the specimen using a Modified C-Scan technique. In order to develope Modified C-Scan technique, an automatic ultrasonic scanner and a module to control the scanner were designed and fabricated. IBM-PC/XT was interfaced to the module to control the scanner. Analog signals from the SONIC MARK II were digitized by Analog-Digital Converter(ADC 0800) for Modified C-Scan display. A computer program has been developed and has capability of automatic data acquisition and processing from the digital data, which consist of maximum amplitudes in each gate range and locations. The data from Modified C-Scan results was compared with shape from artificial defects using the developed system. Focal length of focused transducer was measured. The automatic ultrasonic equipment developed through this study is essential for more accurate, reliable, and repeatable ultrasonic experiments. If the scanner are modified to meet to appropriate purposes, it can be applied to automation of ultrasonic examination of nuclear power plants and helpful to the research on ultrasonic characterization of the materials.

• Journal of Biosystems Engineering
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• 제36권6호
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• pp.467-475
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• 2011

Aerial spraying technology using a small unmanned helicopter is an efficient and practical tool to achieve stable agricultural production to improve the working condition. An attitude controller for the agricultural helicopter would be helpful to aerial application operator. In order to construct the flight controller, a state space model of the helicopter should be identified using a dynamic analysis program, such as CIFER$^{(R)}$. To obtain the state space a model of the helicopter, frequency-sweep flight tests were performed and time history data were acquired using a custom-built stick position transmitter. Four elements of stick commands were accessed for the collective pitch (heave), aileron (roll), elevator (pitch), rudder (yaw) maneuvers. The test results showed that rudder stick position signal was highly linear with rudder input channel signal of the receiver; however, collective pitch stick position signal was exponentially manipulated for the convenience of control stick handling. The acquired stick position and flight dynamic data during sweep tests would be analyzed in the followed study.

• 한국전자파학회논문지
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• 제28권10호
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• pp.825-831
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• 2017

실제 레이다가 운용되는 환경에서 발생되는 클러터는 비균질성(heterogeneous)의 특성을 갖는 동시에 바이스태틱 레이다나 모노스태틱 non-sidelooking 레이다 구조인 경우는 클러터의 비정상성(nonstationary) 특성도 갖는다. 이러한 특성에 의해서 클러터 신호를 추정하는데 필요한 IID(Independent Identically Distributed) secondary 데이터 개수에 제약이 따르므로 클러터 억제 성능이 저하된다. 본 논문에서는 바이스태틱 레이다 환경에서 Cell under test에 대한 사전정보만을 이용하여 클러터 신호를 추정함으로써 secondary 데이터 없이 클러터를 억제하는 알고리즘을 제시한다. 바이스태틱 클러터의 angle-Doppler 스펙트럼 상에서 구조 분석을 통해 사전정보로 부터 클러터를 추정하는 것이 가능함을 보이고, 고유치 해석에 의해 클러터 억제 과정을 제시한다. 마지막으로 시뮬레이션을 통해 제시하는 클러터 억제 알고리즘의 성능을 보인다.