• 한국안전학회지
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• 제20권2호
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• pp.127-132
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• 2005

The purpose of this study is to compare representative posture classification schemes of OWAS, RULA and REBA in terms of correctness for postural load. The comparison was based on the evaluation results by the three methods for 224 working postures sampled from steel, electronics, automotive, and chemical industries. The results showed that OWAS and REBA generally underestimated postural stress than RULA irrespective of industry type, work performed and whether or not leg posture is balanced. While about $71\%\;and\;73\%$ of the 224 posture were evaluated with the action category/level 1 or 2 by OWAS and REBA respectively, about $60\%$ of the postures were classified into the action level of 3 or 4 by RULA. The coincidence rate of postural stress category between OWAS and RULA was just $33.5\%$, while the rate between RULA and REBA was $46.0\%$. It is concluded from the findings of this study and the previous research that compared to OWAS and REBA, RULA more precisely evaluates postural stress.

• 융합정보논문지
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• 제9권5호
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• pp.86-94
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• 2019

본 연구는 스마트폰 중독 분류군 별에 따른 중학생이 지각한 부모의 양육태도와 학업스트레스의 차이를 파악하고, 스마트폰 중독 분류군 별에 영향을 미치는 예측요인을 분석하기 위해 실시된 조사연구이다. 수집된 358명의 자료를 SPSS 18로 기술통계, ${\chi}^2$ test, t-test 및 단계적 다중회귀분석을 실시하였다. 스마트폰 중독 위험자군은 97명(27.0%), 일반 사용자군은 261명(72.9%) 이었다. 스마트폰 중독 위험자군이 일반 사용자군에 비해 부모양육태도를 부정적으로 지각하고 있으며, 학업스트레스 정도는 더욱 높았다. 스마트폰 중독 분류군 별에 따른 예측요인으로는 스마트폰 중독 위험자인 경우에는 매일 스마트폰 사용시간(${\beta}=.29.4$)이, 일반 사용자군은 학업스트레스(${\beta}=.298$)가 가장 강력한 예측요인 이었다. 따라서 스마트폰 중독 분류군 별에 맞는 스마트폰 중독 예방 및 관리 프로그램이 마련된다면, 보다 효과적으로 스마트폰 중독 정도를 감소시킬 수 있을 것이라 기대된다.

• 인간식물환경학회지
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• 제23권1호
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• pp.47-53
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• 2020

This study conducted a horticultural therapy program for trainees entrusted to the Juvenile Classification Review Center in order to fill the educational gap while providing emotional stability during the one-month period of commissioned education. The effects of horticultural therapy were examined by the pretest and posttest changes of the emotional items such as anxiety, self-esteem, self-efficacy and stress index. As the research method, this study used the one-group pretest-posttest experimental design on 16 female trainees of commissioned education staying at the Juvenile Classification Review Center in the juvenile reformatory located in A city. The horticultural therapy program was carried out in four sessions: two on flower arrangement and two on planting. The scores before and after the horticultural therapy program were measured using the Revised Children's Manifest Anxiety Scale (RCMAS) to examine the effects of horticultural therapy on the reduction of anxiety for the adolescents staying in the Juvenile Classification Review Center. The results show that there was significant decrease in the mean of anxiety from 62.5 (SD = 6.8) to 57.6 (SD = 8.1) points after the program (p = .002). There was no significant change in self-esteem, which was 76.9 (SD = 11.2) before the horticultural therapy and 78.3 (SD = 8.7) after the therapy (p = .420). In self-efficacy, there was no significant change from 72.9 (SD = 10.9) before and 75.1 (SD = 11.0) after horticultural therapy (p = .178). In order to examine the physiological changes in such emotional functions, this study measured the stress index using the uBioMacpa as the tool. The result of the measurement showed that there was a significant change in the mean from 33.8 (SD = 2.3) before to 31.1 (SD = 2.2) after the horticultural therapy (p < .001).

• 대한기계학회논문집A
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• 제30권5호
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• pp.520-527
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• 2006

The design of major industrial facilities for the prevention of fatigue failure is customarily done by defining a set of transients and performing a calculation of cumulative usage factor. However, sometimes, the inherent conservatism or lack of details as well as unanticipated transients in old plant may cause maintenance problems. Even though several famous on-line monitoring and diagnosis systems have been developed world-widely, in this paper, a new system fur fatigue monitoring and life evaluation of crane is proposed to reduce customizing effort and purchasing cost. With regard to the system, at first, comprehensive operating transient data has been acquired at critical locations of crane. The real-time data were classified, by using adaptive resonance theory that is one of typical artificial neural network, into representative stress groups. Then the each classified stress pattern was mapped to calculated cumulative usage factor in accordance with ASME procedure. Thereby, promising results were obtained fur the crane and it is believed that the developed system can be applicable to other major facilities extensively.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.257-262
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• 2006

Insulation failure in an electrical utility depends on the continuous stress imposed upon it. Monitoring of the insulation condition is a significant issue for safe operation of the electrical power system. In this paper, comparison of recognition rate variable classification scheme of PD (partial discharge) sources that occur within an electrical utility are studied. To acquire PD data, five defective models are made, that is, air discharge, void discharge and three types of treeinging discharge. Furthermore, these statistical distributions are applied to classify PD sources as the input data for the classification tools. ANFIS shows the highest rate, the value of which is 99% and PCA-LDA and ANFIS are superior to BP in regards to other matters.

• 대한토목학회논문집
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• 제8권1호
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• pp.61-68
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• 1988

본(本) 연구(硏究)에서는 군용전차의 교량통과시 노후도(老朽度)를 비롯한 각종 저항(抵抗) 및 하중(荷重)관련 불확실량(不確實量)을 체계적으로 포함한 한계상태모형(限界狀態模型)을 유도하고, 실용적이며 진보된 2차(次)모멘트 신뢰성(信賴性) 이론(理論)을 사용하여 군용교량(軍用橋梁) 및 일반교량(一般橋梁)의 신뢰성(信賴性)에 기초한 안전도(安全度) 분석방법(分析方法)과 하중저항계수(荷重抵抗係數) 형식의 급수계산방법(級數計算方法)을 제안(提案)하였다. 본(本) 연구(硏究)에서 제안(提案)하는 안전도(安全度) 분석(分析) 및 내하급수(耐荷級數) 판정방법(判定方法)을 몇 개의 실제 교량에 적용하여 보았다. 본(本) 연구(硏究)의 결과 현행 재래식 허용응력개념에 의한 NATO 급수계산방법은 실내하력(實耐荷力) 판정(判定)이 아닌 명목적인 급수판정방법에 불과함을 알 수 있으며, 따라서 본 연구에서 제시(提示)한 신뢰성방법(信賴性方法)에 의한 안전도(安全度) 분석방법(分析方法)과 하중(荷重)-저항계수(抵抗係數)형 급수 계산방법이나 이에 대응하는 합리적인 허용응력법(許容應力法)에 의한 실내하급수(實耐荷級數) 계산방법(計算方法)의 도입이 시급하다고 본다.

• 한국콘텐츠학회논문지
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• 제14권2호
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• pp.409-420
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• 2014

본 연구는 직업분류 및 고용분류별 스트레스, 스트레스 상담, 우울증상, 우울증상 상담 정도를 파악하기 위해 지역사회건강조사 자료를 이차 분석하였다. 직업분류별 및 고용분류별 확실한 비교를 위해 기준 직업군으로 '무직(직업분류 기준항목)'과 '무급가족종사자(고용분류 기준항목)'를 포함하여 한국표준직업분류(6차 개정)에 의한 총 13개의 직업군을 이용하였다. 직업분류 및 고용분류별 스트레스, 스트레스 상담, 우울증상, 우울증상 상담 여부의 교차비에서는 '무직'과 '무급가족종사자'의 스트레스 정도가 대체적으로 더 낮게 나타난 반면, 스트레스 상담, 우울증상, 우울증상 상담에서는 '무직'과 '무급가족종사자'가 오히려 더 높은 교차비를 보였다. '관리직'을 포함한 7개의 직업군은 '무직'보다 스트레스를 많이 받지만(OR > 1), 의료기관 이용률은 낮게 나타났다(OR < 1). '고용주 및 자영업자'와 '임금근로자'가 '무급가족종사자'에 비해 높은 교차비를, 스트레스 상담 및 우울상담에서는 낮은 교차비를 보였다. 본 연구는 정신건강문제 선별 및 관리를 위해 특정 인구집단에 대한 접근을 통해 직장 내 정신보건서비스 제공에 대한 필요성을 시사하고 있다.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.47-54
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• 1995

This study was to measure the properties of logs and classify them by non-destructive methods. The purpose of this experiment was focused at mensurability of logs by non-destructive methods. The non-destructive instrument, Stress-Wave Timer 239A which was made by Metriguard in U.S.A., was used. The stress wave velocities of log's cross direction were measured and compared with three different methods; 1. with hammer, 2. with hammer and D.B.H. meter, 3. with manufactured instrument. Number of used logs were seven logs, which were classified by naked eye into six groups; very severe rot, severe rot, mild rot & knot, mild rot & check, mild rot, sound log, and in diameter were into three groups; large(57.4cm), medium(36~41.2cm), small(28.9cm) log. The results, which were classified by mensurability with non-destructive methods, were followed; 1. The stress wave velocities were very different between rot and sound log. So it meant the possibility of mensurability of logs by non-destructive method even if high standard error. 2. The stress wave velocities decreased with checks more than with rots, which meant the checks affected speeds more. 3. The stress wave velocities increased with knot. 4. The velocities with manufactured instrument showed lower standard error, so more accurate results than other methods. Especially the required labour decreased from 3~4 to 2 persons. 5. Finally, the mensurability showed more accurate results and made the classification of logs scientific.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권12호
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• pp.3943-3959
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• 2022

People are constantly exposed to stress and anxiety environment, which could contribute to a variety of psychological and physical health problems. Therefore, it is particularly important to identify psychological stress in time and to find a feasible and universal method of stress reduction. This research investigated the influence of different music, such as relaxation music and natural rhythm music, on stress relief based on Electroencephalogram signals. Mental arithmetic test was implemented to create a stressful environment. 23 participants performed the mental arithmetic test with and without music respectively, while their Electroencephalogram signal was recorded. The effect of music on stress relief was verified through stress test questionnaires, including Trait Anxiety Inventory (STAI-6) and Self-Stress Assessment. There was a significant change in the stress test questionnaire values with and without music according to paired t-test (p<0.01). Furthermore, a model based on Transformer for stress level classification from Electroencephalogram signal was proposed. Experimental results showed that the method of listening to relaxation music and natural rhythm music achieved the effect of reducing psychological stress and the proposed model yielded a promising accuracy in classifying the Electroencephalogram signal of mental stress.

• Smart Structures and Systems
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• 제29권4호
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• pp.589-598
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• 2022

Timber structures are susceptible to structural damages caused by variations in moisture content (MC), inducing severe durability deterioration and safety issues. Therefore, it is of great significance to detect MC levels in timber structures. Compared to current methods for timber MC detection, which are time-consuming and require bulky equipment deployment, Lead Zirconate Titanate (PZT)-enabled stress wave sensing combined with statistic machine learning classification proposed in this paper show the advantage of the portable device and ease of operation. First, stress wave signals from different MC cases are excited and received by PZT sensors through active sensing. Subsequently, two non-baseline features are extracted from these stress wave signals. Finally, these features are fed to a statistic machine learning classifier (i.e., naïve Bayesian classification) to achieve MC detection of timber structures. Numerical simulations validate the feasibility of PZT-enabled sensing to perceive MC variations. Tests referring to five MC cases are conducted to verify the effectiveness of the proposed method. Results present high accuracy for timber MC detection, showing a great potential to conduct rapid and long-term monitoring of the MC level of timber structures in future field applications.