• 여성건강간호학회지
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• 제27권2호
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• pp.113-127
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• 2021

Purpose: This study examined health behaviors, use of health services, and depression among women who perform daytime and shift work in Korea, as well as factors related to depression. Methods: We conducted a secondary analysis using data from the 2018 data of the 7th Korea National Health and Nutrition Examination Survey. Data on women, 1,493 regular daytime workers and 322 shift workers, were analyzed. Results: Women shift workers (χ²=43.97, p<.001), had a lower education level (χ²=45.56, p<.001), and lower personal income (χ²=16.85, p=.030) than their daytime counterparts. A higher proportion of shift workers were unmarried (χ²=37.47, p<.001) and they typically worked fewer than 40 hours per week (χ²=69.94, p<.001). The depression score of shift workers was higher than that of daytime workers (t=2.85, p=.005). A higher proportion of shift workers also drank alcohol (χ²=6.49, p=.032) and smoked (χ²=30.79, p<.001). Over 8% of shift workers typically slept fewer than 5 hours per night (χ²=14.17, p=.024). It was confirmed that depression in women shift workers was affected by age, personal income, marital status, health status, and smoking status, in addition to cancer screening participation, unmet medical care needs, and unmet dental care needs. Conclusion: More attention should be given to the health needs of women working shifts. Health promotion programs specific for women shift workers are needed to improve their physical and mental health, encourage use of medical care services, and improve public health policies and systems.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1692-1699
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• 2015

This paper presents an analysis of the mechanism of failure modes in bi-directional phase-shift full-bridge converters, composed of MOSFET, based on the circuit operation and parasitic parameters of MOSFET. In addition, the relation between circuit operation and parameters is suggested through an experimental comparison. From this relation, the suitable ranges of parameters for stable performance are analyzed. The design criteria of the bi-directional phase-shift full-bridge converter are presented and evaluated from the experimental verification.

• 전기학회논문지
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• 제56권1호
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• pp.156-160
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• 2007

Surface plasmon resonance(SPR) has been widely studied for biological and chemical sensing applications. The present study conducts numerical simulation for the single and bimetallic layer SPR configurations by using the multiple beam interference matrix(MBIM) method to investigate the influence of wave interference and complex refractive indices of materials on optical characteristics such as reflectance and optical phase shift which are used for sensing. First, calculated reflectances are compared with experimental data for validation. In addition, in the single film structures this study finds out the appropriate film thicknesses with minimum reflectance for cases of gold film and silver film. For a bimetallic silver-gold film structure, in particular, the bimetallic film thicknesses that has the minimum reflectance are found 36 nm for silver and 5 nm for gold. From the results, the use of phase shift would be useful compared to reflectance in determining the SPR configuration because the phase shift becomes more sensitive than reflectance.

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.639-646
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• 2002

In this paper, thrust equations for a rubber belt CVT are derived by considering the geometry and mechanism of the mechanical actuators. In order to solve the thrust equations, an algorithm to calculate the speed ratio is suggested for the given driver speed and load torque based on the actuator characteristic equations and existing formula for the belt thrust forces. Experiments are performed to investigate the driver speed-load torque-speed ratio characteristics at a steady state. The speed and torque efficiencies are measured and used to modify the actuator equations. It is found that the modified equations well predict the steady state characteristics. In addition, the shift dynamic model for a rubber belt CVT is derived experimentally. Simulation results of the CVT shift dynamics are in good accordance with the experiments and it is noted that different coefficients are required to describe the CVT shift dynamics for the upshift and the downshift.

• 전기학회논문지
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• 제65권12호
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• pp.2177-2182
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• 2016

Using the existing exact but quite complicated symbol error rate (SER) expressions for M-ary phase shift keying (M-PSK) and M-ary differential phase shift keying (M-DPSK), we derive effective and concise closed-form asymptotic SER formulas especially in Rician-Nakagami fading channels. The derived formulas can be utilized to efficiently verify the achievable error rate performances of M-PSK and M-DPSK systems for the Rician-Nakagami fading environments. In addition, by exploiting the modulation gains directly obtained from the asymptotic SER formulas, we also theoretically demonstrate that M-DPSK suffers an asymptotic SER performance loss of 3.01dB with respect to M-PSK for a given M in Rician-Nakagami fading channels at high signal-to-noise ratio (SNR).

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.618-625
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• 1991

A general expression adopting a nonmultipole expansion method is derived for pseudocontact contribution to the NMR chemical shift arising from the electron orbital angular momentum and electron spin dipolar-nuclear spin angular momentum interaction of $3d^9$ system in a strong crystal field of tetragonally distorted tetrahedral symmetry. From this expression all the multipolar term are determined and the exact solution of ${\Delta}$B/B(ppm) is compared with the multipolar term. The $1/R^5$ term in the multipolar terms contributes dominantly to the NMR chemical shift but the other terms are certainly significant except that of the <111> axis. In addition, an analysis of the temperature dependence of the NMR chemical shift further illustrates that considerable care must be taken in interpeting NMR results in paramagnetic system.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.60-64
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• 2024

The threshold voltage shift in thin-film transistors (TFTs) is modeled using stretched-exponential (SE) and stretched-hyperbola (SH) functions. These models are derived by introducing empirical parameters into reaction rate equations that describe defect generation or charge trapping caused by hydrogen diffusion in the dielectric or interface. Separately, the dielectric relaxation phenomena are also described by the same reaction rate equations based on defect diffusion. Dielectric relaxation was initially modeled using the SE model, and various models have been proposed using fractional calculus. In this study, the characteristics of the threshold voltage shift and the dielectric relaxation phenomena are compared and analyzed to explore the applicability of analytical models used in the field of dielectric relaxation, in addition to the conventional SE and SH models.

• 한국전자파학회지:전자파기술
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• 제3권2호
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• pp.30-38
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• 1992

본 논문에서는 $\pi$/4 shift QPSK에 Trellis 부호화된 변조 기볍(Trellis-Coded Modulation, TCM)을 적용시키기위하여 $\pi$/8 shift 8PSK를 제안하고 위상차에의한 신호 집합 확장과 신호 집합 분할을 수행하 는 trellis 부호화된 $\pi$/8 shift 8PSK를 제안한다. 또한 BER(Bit Error Rate) 성능을 향상시키기위하여 제l차 위상차뿐만아니라 제L차 위상차의 자승 유클리드 거리블 메트릭(Branch Metric)으로 갖는 비터 비 디코더(Viterbi decoder)를 설계한다. 그리고 $\pi$/4 shift QPSK, trellis 부호화된 $\pi$/8 shift 8PSK와 제L차 위상차의 자승 유클리드 거리를 메트릭(Branch Metric)으로 갖는 trellis 부호화된 $\pi$/8 shift 8 8PSK의 BER 특성을 AWGN과 다경로 페이딩 채널에서 Monte Carlo 시플레이션을 통해 알야본다. 제안된 알고리즘은MDPSK에도 적용될 수 있다.

• 한국안광학회지
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• 제14권3호
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• pp.65-73
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• 2009

목적: 노안보정용 안경 착용이 원용굴절력 및 근용가입도 변화에 미치는 영향을 조사하기 위하여 본 연구를 시행하였다. 방법: 42~75세 사이의 안과질환이 없고 백내장 수술 또는 망막질환의 경험이 없으며 교정시력이 20/20이면서 노안보정용 안경 착용 경험이 없는 대상자를 대조군, 돋보기 착용군 및 누진다초점안경 착용군으로 세분한 후 방문 시기에 따라 원용굴절력과 근용가입도를 측정하여 비교분석하였으며 추적 관찰은 최대 73개월 동안 진행하였다. 결과: 원용굴절력은 연령에 따라 원시안으로 변하는 경향이 있었으며(r=0.486, p<0.001) 연구기간 중 대상자의 50.0%에서 플러스 굴절력이 증가하였다. 돋보기 착용군의 년 간 플러스굴절력 증가량은 대조군 및 누진다초점안경 착용군과 유의한 차이를 보였으나(p<0.05), 누진다초점안경 착용군은 대조군과 차이가 없었다. 돋보기 착용군의 연간 근용가입도 증가량도 대조군 및 누진다초점안경 착용군보다 더 많았다(p<0.05). 결론: 중노년층에서는 연령관련 원시화현상이 나타날 수 있기 때문에 정기적인 굴절검사가 반드시 필요하며, 돋보기의 착용은 연령관련원시화 및 근용가입도의 증가를 유발시킬 수 있으나, 누진다초점안경의 처방은 원용굴절력과 근용가입도의 증가를 감소시킬 수 있을 것으로 사료된다.

• 한국산업보건학회지
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• 제29권4호
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• pp.550-561
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• 2019

Objectives: The purpose of this study is to provide basic data for the improvement of the working environment for health prevention and related countermeasures for shift workers. This study was conducted based on the Fifth Korean Working Conditions Survey (KWCS), which analyzed the health effects of shift work forces and compared them with preceding studies. Methods: By analyzing secondary rates using raw data from the 5th KWCS, 4,870 (9.7%) of the 50,184 total study subjects were divided into shift work and 45,314 (90.3%) non-shift work groups based on the response to shift status. Variables that could affect work health issues were identified and corrected. A cross-analysis was conducted to examine demographic characteristics (gender, age, and education level) of the workers and occupation characteristics (monthly net earnings, employment type, occupation, working period up to now, workplace scale, type of work system, and weekly working hours). In order to find the work health issue ratio between the shift and non-shift work groups, logistic regression was analyzed and the association with health problems according to shift type by gender was looked at through cross-analysis. Results: According to the surveys conducted from the 1st KWCS (2006) to the 5th KWCS (2017), the proportion of shift workers continued to increase. Also, muscular pains in the lower limbs (hips, legs, knees, feet, etc.) (OR=1.135, 95%CI 1.031-1.251), headaches, eyestrain (OR=1.580, 95% CI 1.428-1.748), anxiety (OR=1.715, 95% CI 1.402-2.099), difficulty falling asleep (OR=1.391), and other problems (OR=7.392) were reported. In addition, back pain, muscular pains in shoulders, neck and/or upper limbs, muscular pains in lower limbs (hips, legs, knees, feet, etc.), headaches, eyestrain, depression, anxiety, overall fatigue resulted in significant results for both male and female shift workers. Depression and anxiety were higher in female shift/circulation compared to males. Conclusions: The social nets for the health and safety of shift workers should be explored in a variety of ways, including management and supervision of shift sites, attempts to reorganize and improve the shift system, development of workers' health recovery programs, promotion, systematic treatment, and compensation systems.