• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.517-520
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• 2008

A voltage-programming pixel circuit, which compensates the threshold voltage shift of TFTs and the degradation of OLED, is proposed for large sized a-Si:H active matrix organic light emitting diode (AMOLED) applications. Considering threshold voltage variation (or shift), OLED degradation and reverse bias annealing, HSPICE simulation results indicate that luminance error of every gray level is less than 0.4 LSB under the condition of +1V threshold voltage shift and from -0.2 LSB to 2.6 LSB within 30% degradation of OLED in the case of 40-inch full HDTV condition.

• Textile Coloration and Finishing
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• v.6 no.1
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• pp.28-32
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• 1994

The synthesis and absorption spectra of squarvlium(SQ) dyes and croconium(CR) dyes were .studied. Absorption spectra of SQ dye in various solvents exhibited a negative solvatochrornism. Thus, it was suggested that the structure of SQ dye may be a highly polar structure. The λ$_{max}$ of CR dyes undergoes a bathochromic shift of about 100nm compared with the corresponding SQ dyes. This shift can be calculated by the Pariser-Parr-Pople molecular orbital method. From the PPP MO calculation results, we found that SQ dye and CR dye have a almost same Highest Occupied Molecular Orbital(HOMO) level(SQ : -8.0eV, CR : -8.09eV). On the other hand, energy levels of Lowest Unoccupied Molecular Orbital(LUMO) of SQ and CR dyes are -4.09eV and -4.13eV respectively. Thus, replacement of five membered ring by four membered ring in SQ dye causes a large bathochromic shift.t.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.9-10
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• 2016

최근 급속한 산업 발달로 인하여 기존의 수 MW급 대용량 인버터가 산업용 팬, 컴프레서, 고속 철도 시스템 등 여러 분야에 사용되면서 이와 관련된 대용량 인버터 연구가 활발히 진행 중이다. 이런 대용량 인버터는 고효율과 직병렬의 구성된 전력용반도체 소자를 동시다발적으로 제어되어야하기 때문에 멀티레벨 인버터의 구조가 가장 적합하다. Cascaded H-bridge 멀티레벨 인버터는 커패시터와 다이오드를 사용하지 않고 스위치만으로 구성하며, 필터를 따로 구성하지 않아도 정현파와 유사하게 전압을 출력할 수 있다. 이로 인해 고주파 감소 및 각 셀을 직렬로 연결하여 입력전압보다 높은 출력전압을 얻을 수 있다. 또한, 스위칭 방법에 따라 동일한 Cascaded H-bridge 멀티레벨인버터 토폴로지에서도 각 THD와 온도에 따른 손실이 달라질 수 있다. Cascaded H-bridge 멀티레벨 인버터에서 이용하는 스위칭 방식은 첫 번째로 유니폴라 방식을 기본으로 한 Phase-shift가 있다. 이는 180도 위상차를 갖는 2개의 레퍼런스 파형과 위상천이가 된 캐리어 파형의 비교로 PWM (Pulse Width Modulation) 을 수행한다. 두 번째 방식으로는 Level-shift가 있다. 이는 캐리어 파형을 IPD (In-Phase Disposition) 방식으로 수직적으로 대역폭이 연속적이게 나열하여 레퍼런스 파형과 비교하는 PWM방식이다. 본 논문에서는 Phase-shift와 Level-shift 방식에 따른 Cascaded H-bridge 인버터와 NPC (Neutral Point Clamped) 인버터를 결합한 토폴로지에서의 온도에 따른 손실을 분석하고, 시뮬레이션을 통하여 비교 분석하였다.

• Journal of East-West Nursing Research
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• v.17 no.2
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• pp.117-124
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• 2011

Purpose: This study was done to compare organizational commitment, job satisfaction and job stress according to nurses' adult attachment styles. Methods: Data were collected by self-report questionnaires measuring Adult attachment style, Organizational commitment, Job satisfaction and Job stress from a convenience sample of 253 shift nurses in a hospital. Results: There were security style (31.2%), dismissing-avoidance (18.6%), preoccupation (17.8%) and fearful-avoidance (32.4%) among 4 attachment styles in these shift nurses. Their organizational commitment level (M=3.2), job satisfaction (M=2.7) and job stress (M=3.3) were revealed. Subjects who were in security attachment style showed significantly higher scores of organizational commitment (F=5.09, p=.002) and job satisfaction (F=13.02, p<.001) than subjects in fearful-avoidance attachment style. Meanwhile, this study showed that subjects who were in fearful-avoidance attachment style recorded significantly higher scores of job stress than subjects in any other attachment style (F=3.15, p=.026). Conclusion: This study demonstrated a relevant difference in organizational commitment, job satisfaction and job stress in accordance with the attachment style of shift nurses. These results indicate the need for attachment promotion program for shift nurses. And nurses' attachment styles should be considered in future interventions to enhance quality of nursing care.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.25-37
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• 2014

In the present study, we analyzed precipitation patterns and diurnal variation trends of hourly precipitation intensity due to climate change. To that end, we used the hourly precipitation data obtained from 26 weather stations around South Korea, especially Busan, from 1970 to 2009. The results showed that the hourly precipitation was concentrated on a specific time of day. In particular, the results showed the so-called "morning shift" phenomenon, which is an increase in the frequency and intensity of hourly precipitation during the morning. The morning shift phenomenon was even more pronounced when a higher level of hourly precipitation intensity occurred throughout the day. Furthermore, in many regions of Korea, including Busan, this morning shift phenomenon became more prevalent as climate change progressed.

• ETRI Journal
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• v.33 no.3
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• pp.310-319
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• 2011

In this paper, a new soft-fusion approach for multiple-receiver wireless communication systems is proposed. In the proposed approach, each individual receiver provides the central receiver with a confidence level rather than a binary decision. The confidence levels associated with the local receiver are modeled by means of soft-membership functions. The proposed approach can be applied to wireless digital communication systems, such as amplitude shift keying, frequency shift keying, phase shift keying, multi-carrier code division multiple access, and multiple inputs multiple outputs sensor networks. The performance of the proposed approach is evaluated and compared to the performance of the optimal diversity, majority voting, optimal partial decision, and selection diversity in case of binary noncoherent frequency shift keying on a Rayleigh faded additive white Gaussian noise channel. It is shown that the proposed approach achieves considerable performance improvement over optimal partial decision, majority voting, and selection diversity. It is also shown that the proposed approach achieves a performance comparable to the optimal diversity scheme.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.322-326
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• 2004

This paper describes a new iris recognition method based on a shift-invariant wavelet sub-images. For the feature representation, we first preprocess an iris image for the compensation of the variation of the iris and for the easy implementation of the wavelet transform. Then, we decompose the preprocessed iris image into multiple subband images using a shift-invariant wavelet transform. For feature representation, we select a set of subband images, which have rich information for the classification of various iris patterns and robust to noises. In order to reduce the size of the feature vector, we quantize. each pixel of subband images using the Lloyd-Max quantization method Each feature element is represented by one of quantization levels, and a set of these feature element is the feature vector. When the quantization is very coarse, the quantized level does not have much information about the image pixel value. Therefore, we define a new similarity measure based on mutual information between two features. With this similarity measure, the size of the feature vector can be reduced without much degradation of performance. Experimentally, we show that the proposed method produced superb performance in iris recognition.

• The Journal of Korean Obstetrics and Gynecology
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• v.21 no.3
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• pp.231-244
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• 2008

Purpose: The purpose of this study is to analyze body composition, obesity according to working pattern of working women. The subjects were workers in the automobile manufacturing industry. Methods: The subjects consisted of 514 industrial women workers who had received Korean oriental medicine health examination and submitted questionires about working pattern, during 8 months from April 2005 to November 2005. The body composition was measured by X-scan(Jawon medical, Seoul, Korea). We analyzed the relationship between body composition analysis, obesity and shift pattern with $X^2-test$ using the SPSS Ver. 12.0 Results: Regarding the realationship between body composition and working pattern, shift worker group had a significantly higher level of body weight, ratio of body fat, visceral fat and abdominal fat than normal worker. Conclusion: From this study, we can know that shift work can influence on working women's body composition and obesity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.145-152
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• 2019

All machines deteriorate in performance over time. The phenomenon that causes such performance degradation is called deterioration. Due to the deterioration, the process mean of the machine shifts, process variance increases due to the expansion of separate interval, and the failure rate of the machine increases. The maintenance model is a matter of determining the timing of preventive maintenance that minimizes the total cost per wear between the relation to the increasing production cost and the decreasing maintenance cost. The essential requirement of this model is that the preventive maintenance cost is less than the failure maintenance cost. In the process mean shift model, determining the resetting timing due to increasing production costs is the same as the maintenance model. In determining the timing of machine adjustments, there are two differences between the models. First, the process mean shift model excludes failure from the model. This model is limited to the period during the operation of the machine. Second, in the maintenance model, the production cost is set as a general function of the operating time. But in the process mean shift model, the production cost is set as a probability functions associated with the product. In the production system, the maintenance cost of the equipment and the production cost due to the non-confirming items and the quality loss cost are always occurring simultaneously. So it is reasonable that the failure and process mean shift should be dealt with at the same time in determining the maintenance time. This study proposes a model that integrates both of them. In order to reflect the actual production system more accurately, this integrated model includes the items of process variance function and the loss function according to wear level.

• Korean Journal of Occupational Health Nursing
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• v.9 no.2
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• pp.86-93
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• 2000

This study was conducted to find out the degree of tiredness, accumulated tendencies of fatigues in accordance with 3 types of circadian rhythms and 3 types of perceived fatigue signs such as physical, psychological and neurosensory aspects in before and after work at night. Samples were chosen from the 217 intensive care units nurses working in 13 general hospitals which had 3 shift rotating systems, Data were collected from November to December in 1999. Two hundreds seventeen respondents were classified by 3 circadian types such as 59 morning, 110 middle and 48 evening. Circadian type was measured by the circadian type scale which was designed by ${\ddot{O}}stberg$ and Home (1976). in order to estimate the level of tiredness, the investigator used the fatigue checklist designed by the Labor and Health Institute of Japan(1970). Analysis was done by frequency a percentages, ${\chi}^2$ test and repeated measures ANOVA test. The result of this study were as follow: 1. In the general characteristics of the subjects circadian types, moderate type had the large proportion at 50.7% and morning type had 27.2% and evening type had 22.1%. 2. According to the 3 types of fatigue signs, the highest general tendency was 'General weakness' and 'Feeling of headsore' for physically perceived sign, 'Drowsiness' for psychological sign, and 'Uncomfortableness in sight seeing' for neurosensory sign. 3. The most frequently complained fatigue were observed in physical symptoms among physical, mental, and neurosensual symptoms. The percentage of complained was higher after night work than before the work started. 4. There was not any statistical significant difference between the circadian type and the degree of physical, mental, neurosensory fatigue. 5. There was not any statistical significant difference in regarding to each date of night shift except difference between 1st and 2nd days of fatigue perceived physically. Therefore, the study concluded that the fatigue perceived by night shift nurses might be related with shift working condition rather than circadian types.