• Design & Manufacturing
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• 제16권4호
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• pp.52-59
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• 2022

Currently, Korea is an aging society and is expected to become a super-aged society in about four years. X-ray devices are widely used for early diagnosis in hospitals, and many X-ray technologies are being developed. The development of X-ray device technology is important, but it is also important to increase the reliability of the device through accurate data management. Sensor nodes such as temperature, voltage, and current of the diagnosis device may malfunction or transmit inaccurate data due to various causes such as failure or power outage. Therefore, in this study, the temperature, tube voltage, and tube current data related to each sensor and detection circuit of the diagnostic X-ray imaging device were measured and analyzed. Based on QC data, device failure prediction and diagnosis algorithms were designed and performed. The fault diagnosis algorithm can configure a simulator capable of setting user parameter values, displaying sensor output graphs, and displaying signs of sensor abnormalities, and can check the detection results when each sensor is operating normally and when the sensor is abnormal. It is judged that efficient device management and diagnosis is possible because it monitors abnormal data values (temperature, voltage, current) in real time and automatically diagnoses failures by feeding back the abnormal values detected at each stage. Although this algorithm cannot predict all failures related to temperature, voltage, and current of diagnostic X-ray imaging devices, it can detect temperature rise, bouncing values, device physical limits, input/output values, and radiation-related anomalies. exposure. If a value exceeding the maximum variation value of each data occurs, it is judged that it will be possible to check and respond in preparation for device failure. If a device's sensor fails, unexpected accidents may occur, increasing costs and risks, and regular maintenance cannot cope with all errors or failures. Therefore, since real-time maintenance through continuous data monitoring is possible, reliability improvement, maintenance cost reduction, and efficient management of equipment are expected to be possible.

• 산경연구논집
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• 제10권7호
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• pp.71-82
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• 2019

Purpose - This study aims to identify the priorities of medical service quality improvement by customer satisfaction characteristics and potential customer satisfaction improvement (PCSI) index based on the dualistic quality classification of Kano Model (1984) for Comprehensive Health Screeening Center in General Hospitals and Centers only for Comprehensive Health Screening and suggest a direction for future improvement. Research design, data, and methodology - Through advanced research on health screening medical service quality, this study set four service quality factors, including tangible, human, process and supportive factors, and 39 measurement items. Based on these items, the study used 117 questions, which consist of dualistic quality factors, customer satisfaction coefficients, positive and negative questions for PCSI index and questions for current satisfaction. 300 effective samples were collected for adults in their 20s who experienced health screening service in Seoul, Gyeonggi-do and Incheon within the past two years. Collected data were input in the quality evaluation duality table to categorize quality factors and calculate customer satisfaction coefficients by Timko(1993). The study also analyzed PCSI index in comparison with current satisfaction and identified priorities in quality improvement. Results - It was found that the most urgent factors to improve the quality in both groups were adequate waiting hours and emergency response for complications, which are process factors classified as unitary quality. It is urgently needed to improve the quality as the PCSI index was high in supportive factors (complaint response team) as attractive quality in Comprehensive Health Screening Center in General Hospitals and in process factors (prevention of infection) as unitary quality in Centers only for Comprehensive Health Screening. As the PCSI index was low in space use as a tangible factor, it was found that the current level can be maintained instead of improvement. Conclusions - To improve the health screening medical service quality, it is required to focus on process factors (adequate waiting hours, emergency response for complications, prevention of infection) and supportive factors (complaint response team) among service qualities perceived by users. It is proposed to ensure continuous efforts to manage and reinforce priorities as a direction for future improvement in health screening service.

• 대한건축학회논문집:구조계
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• 제36권5호
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• pp.177-185
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• 2020

The building energy performance indicator, called Energy Performance Index (EPI), has been used for the past decades in South Korea. It has a list of design variables assigned with weighting factors (a, b). Unfortunately, the current EPI method is not performance-based but very close to a prescriptive rating. With this in mind, this study aims to propose a new performance-based EPI method. For this purpose, a global sensitivity analysis method, Sobol, is employed. The Sobol method is suitable for complex nonlinear models and can decompose all the output variance due to every input. The Sobol sensitivity index of each variable is defined as 0 to 1 (0 to 100%), and the sum of all sensitivity indices is equal to 1 (100%). In this study, an office building was modeled using EnergyPlus and then the Latin Hypercube Sampling (LHS) was conducted to generate a surrogate model to EnergyPlus. The sensitivity index was suggested to replace weight (a) in the existing EPI. In addition, the discrete weight (b) in the existing EPI was replaced by a set of continuous regression functions. Due to the introduction of the sensitivity index and the continuous regression functions, the new proposed approach can provide far more accurate outcome than the existing EPI (R²: 0.83 vs. R²: 0.01 for cooling, R²: 0.66 vs. R²: 0.01 for total energy). The new proposed approach proves to be more rational, objective and performance-based than the existing EPI method.

• 대한기계학회논문집A
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• 제21권5호
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• pp.819-827
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• 1997

In this paper, a new modeling of a fine actuator for an optical pick-up has been proposed and multiobjective optimization of the actuator has been performed. The fine actuator is constituted of the bobbin which is supported by wire suspension, the coils which wind around the bobbin, and the magnets which cause the magnetic flux. If current flows in the coils, magnetic force is so produced as to be balanced with spring force of wire, so the bobbin is pisitioned. In this model the transfer function from input voltage to output displacementof bobbin has been obtained so that we can describe this integrated system with electromagnetic and mechanical parts. Wire suspension is regarded as a continuous Euler beam, damper as distributed viscous damping, and bobbin as a rigid body which can move up- and down- ward motion only. According to the model, the high frequency dynamic characteristics of the fine actuator can be known and the effect of damping can be investigated while the conventional second order model cannot. In multiobjective optimization, two objective functions have been chosen to maximize the fundamental frequency and the sensitivity with respect to the input voltage of the actuator so that Pareto's optimal solutions have been obtained using .epsilon.-constraint method. These objective functions will satisfy the trends which will enhance the access speed and reduce the tracking error in the optical pick-up technology of next generation. In the result of optimization, we obtain the designs of the optical pick-up fine actuator which has high speed, high sensitivity and low resonant peak. Furthermore, we offer the relation between two object functions so that the designer can make easy choice.

• Journal of Yeungnam Medical Science
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• 제17권1호
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• pp.12-20
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• 2000

The memory of pain can be more damaging than its initial experience. Several factors arc related the directions of pain memory: current pain intensity, emotion, expectation of pain, and peak intensity of previous pain. The possible mechanisms behind the memory of pain are neuroplastic changes of nervous system via peripheral and central sensitization. Peripheral sensitization is induced by neurohumoral alterations at the site of injury and nearby. Biochemicals such as K+, prostaglandins, bradykinin, substance P, histamine and serotonin, increase transduction and produce continuous nociceptive input. Central sensitization takes place within the dorsal horn of spinal cord and amplifies the nociceptive input from the periphery. The mechanisms of central sensitization involve a variety of transmitters and postsynaptic mechanisms resulting from the activations of NMDA receptors by glutamate. and activation of NK-1 tachykinnin receptors by substance-P and neurokinnin. The clinical result of peripheral and central sensitization is hyperalgesia, allodynia, spontaneous pain, referred pain, or sympathetically maintained pain. These persistent sensory responses to noxious stimuli arc a form of memory. The hypothesis of preemptive analgesia is that analgesia administered before the painful stimulus will prevent or reduce subsequent pain and analgesic requirements in comparison to the identical analgesic intervention administered after the painful stimulus, by preventing or reducing the memory of pain in the nervous system. Conventionally, pain management was initiated following noxious stimuli such as surgery. More recently, however many have endorsed preemptive analgesia initiated before surgery. Treatments to control postsurgical pain are often best started before injury activates peripheral nociceptors and triggers central sensitization. Such preemption is not achieved solely by regional anesthesia and drug therapy but also requires behavioral interventions to decrease anxiety or stress. Although the benefit of preemptive analgesia may not be obvious in every circumstance, and in many cases may not sufficient to abolish central sensitization, it is an appropriate and human goal of clinical practice.

• Journal of the korean society of oceanography
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• 제34권1호
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• pp.43-48
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• 1999

The latest-Quaternary paleoceanographic history of the Ulleung Basin, the East Sea (the Sea of Japan) is reconstructed on the base of planktonic foraminifera, oxygen and carbon isotopes, and accelerator mass spectrometer radiocarbon (AMS-$^{14}$C) data from two cores. Sinistral populations of Neogloboquadrina pachyderma are dominant during the last glacial period while dextral forms of Neogloboquadrina pachydeyma are abundant in the Holocene. An abrupt increase in ${\delta}^{18}$O values in both cores that began about 11 ka B.P may indicate the Younger Dryas cooling episode. A low-salinity event, marked by light ${\delta}^{18}$O values (0-1 %), is observed before the Younger Dryas event. As previous works suggested, the low-salinity event is probably due to the freshening of surface water caused by fresh water input from Huang Ho river and/or the excess of precipitation over evaporation. The lowest salinity water in the Ulleung Basin was probably continued from approximately 18 ka B.P. to 15 ka B.P. The ${\delta}^{18}$O values have gradually decreased since the Younger Dryas as a result of the continuous inflow of the warm Tsushima Current into the East Sea.

• Journal of Power Electronics
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• 제9권6호
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• pp.823-834
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• 2009

This paper proposes a high-efficiency single-stage ac/dc converter. The proposed converter features low voltage stresses and reduced switching losses. It operates at the boundary of discontinuous- and continuous-conduction modes by employing variable switching frequency control. The turn-on switching loss of the switch can be reduced by turning it on when the voltage across it is at a minimum. The voltage across the bulk capacitor is independent of the output loads and maintained within the practical range for the universal line input, so the problem of high voltage stress across the bulk capacitor is alleviated. Moreover, the voltage stress of the output diodes is clamped to the output voltage, and the output diodes are turned off at zero-current. Thus, the reverse-recovery related losses of the output diodes are eliminated. The operational principles and circuit analysis are presented. A prototype circuit was built and tested for a 150 W (50V/3A) output power. The experimental results verify the performance of the proposed converter.

• Journal of Power Electronics
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• 제18권5호
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• pp.1303-1314
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• 2018

To match the dynamic lower voltage of a fuel cell stack and the required constant higher voltage (400V) of a DC bus, an H-type structural Boost three-level DC-DC converter with a wide voltage-gain range (HS-BTL) is presented in this paper. When compared with the traditional flying-capacitor Boost three-level DC-DC converter, the proposed converter can obtain a higher voltage-gain and does not require a complicate control for the flying-capacitor voltage balance. Moreover, the proposed converter, which can draw a continuous and low-rippled current from an input source, has the advantages of a wide voltage-gain range and low voltage stress for power semiconductors. The operating principle, parameters design and a comparison with other converters are presented and analyzed. Experimental results are also given to verify the aforementioned characteristics and theoretical analysis. The proposed converter is suitable for application of fuel cell systems.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1187-1194
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• 2017

In this paper, a high step-up DC-DC PWM converter with continuous input current and low voltage stress is presented for renewable energy application. The proposed converter is composed of a boost converter integrated with an auxiliary step-up circuit. The auxiliary circuit uses an additional coupled inductor and a balancing capacitor with voltage doubler and switching capacitor technique to achieve high step-up voltage gain with an appropriate switch duty cycle. The switched capacitors are charged in parallel and discharged in series by the coupled inductor, stacking on the output capacitor. In the proposed converter, the voltage stress on the main switch is clamped, so a low voltage switch with low ON resistance can be used to reduce the conduction loss which results in the efficiency improvement. A detailed discussion on the operating principle and steady-state analyses are presented in the paper. To justify the theoretical analysis, experimental results of a 200W 40/400V prototype is presented. In addition, the conducted electromagnetic emissions are measured which shows a good EMC performance.

• 정보처리학회논문지D
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• 제15D권1호
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• pp.23-30
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• 2008

유비쿼터스 환경에서 상황정보 인식 분야를 연구하면서 가장 밑바탕에서 기초가 될 수 있는 것은 인터넷 기술과 XML(Extensible Markup Language)이다. 인터넷을 통한 통신에서 XML 데이터의 사용이 일반화되고 있으며 데이터의 형태는 연속적이다. 그리고 XML 스트림 데이터에 대한 질의를 처리하기 위한 방안들이 제시되고 있다. 이 논문에서는 스트림 데이터에 대한 질의처리를 효율적으로 수행하기 위한 기반연구로써 XML을 레이블의 순서화된 트리로 모델링하여 온라인 환경에서 빈발한 구조를 추출하는 마이닝 방법을 제안한다. 즉, 지속적으로 입력되는 XML 데이터의 구조를 트리로 모델링하고 각각의 트리를 하나의 트리 집합의 구조로 표현하여 현재 윈도우 시점에서 빈발한 구조를 정확하고 빠르게 추출하는 방법을 제시한다. 제시하는 방법은 XML의 질의 처리 및 색인 구성의 기초 자료로 활용될 수 있다.