• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.241-249
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• 2017

This paper presents the design and evaluation of the optical system for an uncooled thermal-imaging camera. The operating wavelength range of this system is from $7.7{\mu}m$ to $12.8{\mu}m$. Through optimization, we have obtained a LWIR (Long Wave Infrared) optical system with a focal length of 5.44 mm, which consists of four aspheric surfaces and two diffractive surfaces. The f-number of the optical system is F/1.2, and its field of view is $90^{\circ}{\times}67.5^{\circ}$. The hybrid lens was used to balance the higher-order aberrations, and its diffraction properties were evaluated by scalar diffraction theory. We calculated the polychromatic integrated diffraction efficiency, and the MTF drop generated by background noise. We have evaluated the thermal compensation of a LWIR fixed optical system, which is optically passively athermalized to maintain MTF performance in the focal depth. In conclusion, these design results are useful for an uncooled thermal-imaging camera.

• Safety and Health at Work
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• v.11 no.4
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• pp.418-424
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• 2020

Background: According to the previous studies, the work-related accident rate decreased in Korea after the introduction of occupational health and safety management system (OHSMS), but there were several disasters in Korea such as subway worker's death at Guui station in 2016 and the Taean thermal power plant accident in 2018, which escalated the social demand for safety. In 2018, OHSMS became an international standard, as ISO45001 was announced. Methods: A survey was conducted to research the implementation status of OHSMS and changes in people's perception, and the results were compared with those of a past survey. Results: Enhanced social demand and various stakeholders' (not only buyer) needs, and social responsibility are perceived as the motivation for the introduction of OHSMS rather than legal compliance or customer demand. In the questionnaire about problems with the implementation of OHSMS, the factors with higher response rate in 2018 than 2004 were "excessive cost" and "complicated documentation management." In the questionnaire about how to promote OHSMS in organizations, most people answered "reduction of workers' compensation insurance rate" in 2004, but most people answered "exemption from health and safety supervision" in 2018. Conclusion: For the effective implementation of ISO45001, emphasis is placed on social demand, training to recognize health and safety as a part of management, and the reduction of certification and consulting costs to promote the introduction of OHSMS. Incentives such as insurance premium cuts and exemptions from health and safety supervision are needed.

• The Journal of Korean Institute of Information Technology
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• v.17 no.6
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• pp.103-114
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• 2019

Moving-target detection using frequency-modulated continuous-wave (FMCW) radar systems has recently attracted attention. Detection tasks are more challenging with noise resulting from signals reflected from strong static objects or small moving objects(clutter) within radar range. Robust Principal Component Analysis (RPCA) approach for FMCW radar to detect moving objects in noisy environments is employed in this paper. In detail, compensation and calibration are first applied to raw input signals. Then, RPCA via Gradient Descents (RPCA-GD) is adopted to model the low-rank noisy background. A novel update algorithm for RPCA is proposed to reduce the computation cost. Finally, moving-targets are localized using an Automatic Multiscale-based Peak Detection (AMPD) method. All processing steps are based on a sliding window approach. The proposed scheme shows impressive results in both processing time and accuracy in comparison to other RPCA-based approaches on various experimental scenarios.

• Safety and Health at Work
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• v.12 no.1
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• pp.74-95
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• 2021

Background: A job-exposure matrix (JEM) is an important surrogate indicator to evaluate past exposure levels. Although a Korean asbestos JEM has been constructed previously, this JEM includes only a few industrial and occupational groups. This study aimed to reconstruct the JEM by integrating the latest organized data to improve its utility. Methods: We used recent Korean standard industry and occupation codes and extracted 36 articles from a systematic literature review to initiate the reconstruction of the previous Korean asbestos JEM. The resulting data consisted of 141 combinations of industrial and occupational groups. Data from the Netherlands's JEM were also reviewed and categorized into 70 industrial and 117 occupational groups by matching with the Korean data. We also utilized Germany's data, which consisted of 10 industrial and 14 occupational groups. Results: The reconstructed Korean asbestos JEM had 141 combinations of industries and occupations. The time periods are from the 1980s to the 2000s in 10-year intervals. Most of the data were distributed between the 1990s and the 2000s. Occupations with high exposure to asbestos included knitting and weaving machine operators, automobile mechanics or assemblers, ship mechanics or assemblers, mineral ore and stone products processing mechanics, and metal casting machine operators or mold makers. Conclusions: The reconstructed Korean asbestos JEM has expanded the type and duration of the occupational groups of the previous JEM and can serve as an important reference tool for evaluating asbestos exposure and designing compensation and prevention policies in Korea.

• Safety and Health at Work
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• v.13 no.3
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• pp.279-285
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• 2022

Background; In the event of an industrial accident, the appropriate choice of hospital is important for worker health and prognosis. This study investigates whether the choice of hospital by the employer in the case of industrial accidents affects the prognosis of injured employees. Methods; Data from the 2018 Panel Study of Workers' Compensation Insurance in Korea were used in an unmatched case-controlled study. The exposure variable is "hospital selection by an employer," and the outcome variable is 'worker's disability." Odds ratios (ORs) were estimated by modified Poisson regression and adjusted for age, gender, underlying disease, injury severity, and workplace size and stratified by industrial classification. The group at increased risk was analyzed and stratified by age, gender, and area. Results; In the construction industry, hospital selection by the employer was significantly associated with increased risk of disability (adjusted OR 1.26; 95% confidence interval [CI]; 1.20-1.32) and severe disability (adjusted OR 1.38; 95% CI; 1.08-1.76) among the injured. Female and younger workers not living in the Seoul capital area were more at risk of disability and severe disability than those living in the Seoul capital area. Conclusions; Hospital selection by employers affects the prognosis of workers injured in an industrial accident. For protecting workers' health and safety, workplace emergency medical systems should be improved, and the selection of appropriate hospitals to supply treatment should be reviewed.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.411-412
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• 2009

최근 시각 기반 인터페이스를 위하여, 손 동작 인식 기술 개발의 필요성이 증가하고 있다. 이러한 손 동작 인식 기술에서 손 모양 인식은 중요한 부분이며, 이는 손 영역 검출의 결과에 많은 영향을 받는다. 기존의 많은 손 동작 인식 기술들은 사람의 피부색이 갖는 컬러 특징을 이용하여 손 영역을 검출하였다. 그러나, 이러한 컬러 정보는 배경 및 조도 변화에 매우 민감하다. 이러한 문제를 해결하기 위해 본 논문에서는, 색 온도 보정 과정을 손 영역 검출에 적용함으로써 배경 및 조도 변화에 강인한 손 모양 인식 시스템을 제안한다. 제안한 방법이 배경 및 조도 변화에 강인함을 보이기 위해, 조명의 밝기 수준을 조절하며, 다양한 색을 배경으로 찍은 손 영상을 입력으로 손 모양 인식 성능을 실험하였다. 기존의 피부색을 이용한 손 영역 검출과의 비교 실험 결과를 통해, 제안한 방법이 배경 및 조도 변화에 강인한 손 모양 인식 성능을 가짐을 확인하였다.

• Physical Therapy Korea
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• v.29 no.2
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• pp.165-170
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• 2022

Background: The serratus anterior (SA) muscle prevents scapular winging (SW) by stabilizing the medial border of the scapula during arm movement. The upper trapezius (UT) and lower trapezius (LT) muscles may compensate for the weak SA muscle in individuals with SW during shoulder flexion. However, there is no study to examine whether compensation by UT and LT occurs in individuals with SW. Objects: This study compared the muscle activities of UT, LT, and SA as well as the SA/UT activity ratio between individuals with and without SW during shoulder flexion with load. Methods: This study recruited 27 participants with SW (n = 14) and without SW (n = 13). Electromyography data of the SA, UT, and LT muscles and SA/UT activity ratio were recorded and analyzed during shoulder flexion with 25% load of the maximal shoulder flexion force. Independent t-test was used to compare the UT, LT, and SA muscle activities and SA/UT ratio between the groups with and without SW; statistical significance was set at α of 0.05. Results: SA activity was significantly lesser in the group with SW than in the group without SW. However, there were no significant differences in the UT and LT activities and SA/UT activity ratio between the two groups. Conclusion: The SA activity was lesser in the group with SW than in the group without SW with 25% load of the maximal shoulder flexion force, but there was no compensatory muscle activity of the UT and LT observed. Therefore, further studies are warranted to clarify the compensatory strategy of scapular stabilization in individuals with SW during shoulder flexion under other heavy load conditions.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.55 no.8
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• pp.498-507
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• 2012

Background and Objectives We aimed to develop a Korean version of the velopharyngeal insufficiency (VPI) speech corpus system. Subjects and Method After developing a 3-channel simultaneous speech recording device capable of recording nasal/oral and normal compound speech separately, voice data were collected from VPI patients aged more than 10 years with/without the history of operation or prior speech therapy. This was compared to a control group for which VPI was simulated by using a french-3 nelaton tube inserted via both nostril through nasopharynx and pulling the soft palate anteriorly in varying degrees. The study consisted of three transcriptors: a speech therapist transcribed the voice file into text, a second transcriptor graded speech intelligibility and severity and the third tagged the types and onset times of misarticulation. The database were composed of three main tables regarding (1) speaker's demographics, (2) condition of the recording system and (3) transcripts. All of these were interfaced with the Praat voice analysis program, which enables the user to extract exact transcribed phrases for analysis. Results In the simulated VPI group, the higher the severity of VPI, the higher the nasalance score was obtained. In addition, we could verify the vocal energy that characterizes hypernasality and compensation in nasal/oral and compound sounds spoken by VPI patients as opposed to that characgerizes the normal control group. Conclusion With the Korean version of VPI speech corpus system, patients' common difficulties and speech tendencies in articulation can be objectively evaluated. Comparing these data with those of the normal voice, mispronunciation and dysarticulation of patients with VPI can be corrected.

• Safety and Health at Work
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• v.14 no.3
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• pp.332-339
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• 2023

Background: The aim of the study was to test the validity and reliability of the Perceived Future Decent Work Securement Scale for Turkish nursing students. Methods: A cross-sectional, methodological study design was used. The study was carried out at three nursing undergraduate programs in Turkey during the academic year of 2020-2021 with 336 senior nursing students. Language validity and content validity analyses were performed for the scale adaptation, followed by confirmatory factor analysis (CFA) for construct validity. The reliability of the scale was determined using the test-retest and Cronbach's alpha internal consistency coefficient. Results: The scale-content validity index score was 0.988. In CFA, all goodness-of-fit indices verified the acceptable fit of the model; its root mean square error of approximation was 0.076; the normed fit index was 0.909; the standardized mean square residual was 0.097; the relative fit index was 0.881; the goodness-of-fit index was 0.915; the adjusted goodness-of-fit index was 0.872 and χ²/df = 2.932. The overall reliability was α = 0.86. The item-total correlations of the scale were above the acceptable level, and the test-retest analysis had a high correlation. The access to healthcare (14.68, SD 3.53) obtained the highest average score, and the adequate compensation (8.52, SD 3.76) was the lowest rated by the senior nursing students. Conclusion: The Perceived Future Decent Work Securement Scale is a valid and reliable scale to assess nursing students' future decent work securement.

• Physical Therapy Korea
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• v.31 no.1
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• pp.55-62
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• 2024

Background: The serratus anterior (SA) is a muscle that performs protraction of the scapulothoracic joint and plays a role in stabilizing the scapula. Imbalances or weaknesses in SA activation are associated with a variety of shoulder dysfunctions, making selective SA strengthening important for rehabilitation. Objects: We aimed to compare the muscle activation of the pectoralis major (PM), SA, external oblique (EO), and internal oblique (IO) during the push-up plus (PUP) exercise with isometric hip adduction (HA) and abdominal drawing-in maneuver (ADIM). Methods: Nineteen healthy male participants performed three PUP exercises: standard PUP, PUP with ADIM, and PUP with HA. Surface electromyography was used to measure and analyze the muscle activity for PM, SA, EO, and IO. Results: PUP with HA showed the lowest PM activity and highest SA activity, and no significant difference was observed between PUP and PUP with ADIM. PUP with ADIM showed significantly the highest EO and IO activity, followed by PUP with HA and PUP. Additionally, PUP with HA showed the lowest PM/SA ratio, and no significant difference was noted between PUP and PUP with ADIM. Conclusion: PUP with HA was able to show high SA muscle activity while reducing PM muscle activity. In addition, PUP with HA can lead to higher EO and IO muscle activity than standard PUP. This exercise could be used as a practical exercise method to selectively strengthen SA and improve scapular muscle stability during early shoulder rehabilitation.