• Design & Manufacturing
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• 제14권4호
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• pp.17-24
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• 2020

Products for heating indoors in low temperature and dry winter are largely divided into products using fossil fuels and products using electricity. The fossil fuels can warm the entire space by convection, but there is a high risk of fire and the frequent ventilation due to the increase in carbon monoxide and carbon dioxide. Heaters using electricity are mainly used because they are convenient to use and are cheap. However, these products can not efficiently warm the air because they use radiation energy. In other words, only the front part exposed to the heater is warm, and the rear part has no heating effect at all. Also, because it emits a large amount of light, fatigue of the eyes is very high. Another problem is that when using electric heaters, the room tends to be dry by high heat. Indoor humidity maintenance is a very important factor in the prevention and treatment of respiratory diseases. Especially, it is essential for health care for infants, bronchial organs and people with weak respiratory because humidity is low in winter. In this study, we conducted a study to develop a product that can improve heating efficiency while maintaining proper indoor humidity by combining heat energy and moisture particles. The concept of humidification and heating at the same time, moisture particles generated in the humidifier pass through the heater, include thermal energy, and the moisture particles with thermal energy are diffused into the space by forced convection, thereby warming the entire space. In addition, the heating time is shortened as the feeling temperature is increased with the high relative humidity, and this has the effect that the heating cost in winter is reduced.

• 한국정보기술학회논문지
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• 제17권5호
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• pp.105-116
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• 2019

국내 대다수의 공공장소 및 사유건물은 범죄 예방 및 사후 조치, 내부자 보안, 시설안전 및 화재 예방 등을 위해 CCTV(Closed Circuit Television)를 설치하고 있으며, 매년 설치 대수는 늘어나는 추세이다. 늘어나는 CCTV에 대하여 진행된 설문에서는 다수의 반응이 CCTV의 촬영으로 인한 프라이버시 침해 등의 부정적 시선보다 설치로 인해 발생할 수 있는 범죄의 예방적 측면에서 긍정적으로 보고 있다. 하지만 CCTV는 프라이버시 측면에서 많은 위험성을 내포하고 있으며, 클라우드를 이용하여 영상 데이터를 수집할 경우 피사체의 개인정보가 유출될 수 있다. 인세캠은 각국의 CCTV 감시 영상을 실시간으로 중계하였으며, 중계 대상에는 노트북의 전면카메라까지 포함되어 큰 이슈를 불러일으켰다. 본 논문에서는 CCTV를 통해 영상정보에 대한 프라이버시 기법 처리를 통한 개인정보 유출 방지 및 클라우드 시스템 보안성 강화를 위한 시스템을 소개하기로 한다.

• 대한조선학회논문집
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• 제57권6호
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• pp.322-330
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• 2020

This study deals with underwater explosion (UNDEX) characteristics of various non-explosive underwater shock sources for the development of non-explosive underwater shock testing devices. UNDEX can neutralize ships' structure and the equipment onboard causing serious damage to combat and survivability. The shock proof performance of naval ships has been for a long time studied through simulations, but full-scale Live Fire Test and Evaluation (LFT&E) using real explosives have been limited due to the high risk and cost. For this reason, many researches have been tried to develop full scale ship shock tests without using actual explosives. In this study, experiments were conducted to find the characteristics of the underwater shock waves from actual explosive and non-explosive shock sources such as the airbag inflators and Vaporizing Foil Actuator (VFA). In order to derive the empirical equation for the maximum pressure value of the underwater shock wave generated by the non-explosive impact source, repeated experiments were conducted according to the number and distance. In addition, a Shock Response Spectrum (SRS) technique, which is a frequency-based function, was used to compare the response of floating bodies generated by underwater shock waves from each explosion source. In order to compare the magnitude of the underwater shock waves generated by each explosion source, Keel Shock Factor (KSF), which is a measure for estimating the amount of shock experienced by a naval ship from an underwater explosionan, was used.

• 한방재활의학과학회지
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• 제32권3호
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• pp.29-35
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• 2022

Objectives The purpose of this systematic review is to analyse randomized controlled trials about acupuncture for patellofemoral pain syndrome (PFPS) and evaluate it's pain improvement effect. Methods Studies will be searched from ten databases (Medline/PubMed, Cochrane Library, EMBASE, China National Knowledge Infrastructure [CNKI], WanFang Data, Citation Information by NII [CiNII], ScienceON, Koreanstudies Information Service System [KISS], KMBASE, and KoreaMed). Participants will be patients diagnosed with PFPS, regardless of cause, gender, age or race, and interventions will be acupuncture, electroacupuncture, dry needling, fire needle, and acupotomy. Other treatments than interventions will be the control group and the main outcome will be reviewed by visual analogue scale (VAS). Results Data will be extracted and assessed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis flow chart and Cochrane risk of bias tools. Meta-analysis will be conducted using random effect model within 95% confidence interval. Conclusions We expect this systematic review to provide useful data about the pain improvements of patellofemoral pain using acupuncture and expect to stimulate and systematize acupuncture treatment on PFPS in the future.

• 한국정보통신학회논문지
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• 제26권11호
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• pp.1644-1652
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• 2022

체험자의 안전 문제로 실질적인 훈련이 불가능한 안전 훈련의 경우 가상현실이나 증강현실 같은 실감미디어를 이용한 훈련 콘텐츠가 새로운 대안이 되고 있다. 본 논문에서는 실감미디어 기술로 구현되는 안전 훈련 콘텐츠에 적용될 수 있는 연기 모델링 방법을 제안한다. 석유화학 플랜트와 같은 위험 지역에 사고가 발생하면 가스 유출 및 화재 발생으로 인해 시야가 확보되지 않는 상황이 발생한다. 이런 상황을 연출하기 위해서는 연기를 사실적으로 표현하는 것이 중요하다. 제안하는 방법은 석유화학 플랜트와 같이 통로와 장치가 복잡한 배경에 효과적으로 적용할 수 있는 연기 모델 기법이다. 제안하는 방법에서는 장면 렌더링이 완료된 이미지에 대한 포스트 프로세싱 단계에서 볼륨 렌더링을 이용하여 연기를 표현한다. 공장을 배경으로 구현한 결과를 보면 제안하는 방법이 사용자의 움직임에 따른 연기의 변화를 사실적으로 표현하는 것을 볼 수 있다.

• Journal of Korea Trade
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• 제24권7호
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• pp.38-53
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• 2020

Purpose - A financial crash triggers asset fire sales by foreign investors and, as a consequence, the price of domestic assets severely decreases. Domestic investors take advantage of these low prices by replacing foreign assets with domestic assets, which helps to alleviate the liquidity shock caused by foreigners. However, is the amount of capital retrenchment by domestic investors sufficient to protect the Korean economy from capital stop by foreign investors during financial crisis? This paper answers this question and suggests the implications of this phenomenon for the Korean economy. Design/methodology - We estimate the associations between capital stop and retrenchment and various financial crises such as banking, currency, debt, and inflation crises using the complementary log-log model. Specifically, we use data of gross capital flows to differentiate between the role of foreign and domestic investors in financial markets. Capital stop and retrenchment designate a sharp decrease in gross capital inflows and outflows, respectively. Findings - Capital stop is significantly associated with financial crises, especially currency and debt crises. This implies that increased risk aversion during times of financial turmoil encourages foreign investors to retrench their investments, worsening liquidity shocks. Conversely, capital retrenchment is not significantly associated with such crises. The results show that, although financial crises reduce gross capital outflows, the reduction is not as large as that with capital inflows. Originality/value - The contribution of this paper is threefold. First, this study investigates how domestic investors behave during times of financial distress by studying gross capital flows-not net capital flows. Second, we concentrate on sharp changes in capital flows during crises. Third, we examine the associations between capital stop and retrenchment and financial crises in general, not specific events.

• 한국가스학회지
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• 제26권6호
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• pp.65-75
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• 2022

최근 수전해설비의 운전압력이 증가함에 따라 수소 누출로 인한 화재 및 폭발 가능성 및 위험성 또한 증가하고 있다. 따라서 관계법령 및 기술기준에 따라 수전해 시스템에 설치되는 모든 전기기에 전기방폭 형식인증 제품을 사용하거나 적절한 방법에 따른 비폭발위험장소화 절차를 적용해야 한다. 본 연구에서는 수전해설비의 일반적인 운전조건을 고려하여 KS C IEC 60079-10-1 및 KGS GC101에 따른 폭발위험장소 구분 및 범위 산정을 수행하였다. 또한, 비폭발위험장소화를 달성하기 위해 임계농도인 폭발하한 25 % 미만의 농도를 유지하기 위한 적정 환기량을 검토하였다. 그 결과 자연환기만 적용할 경우에는 수전해설비가 폭발위험장소로 구분되고, 이를 강제환기를 통해 비폭발위험장소로 구분하기 위해서는 막대한 환기량이 필요함을 확인할 수 있었다.

• 한국포장학회지
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• 제28권2호
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• pp.143-149
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• 2022

PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.781-786
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• 2021

Korean domestic workers are trend to avoid harmful and dangerous jobs calls 3D work due to the poor working conditions. Therefore, the incoming population of foreign workers is increasing to fulfill the required labor force. Mostly these foreign workers are placed in small and medium-size industries. As work that induces musculoskeletal disorders(WMSD) is equally exposed to domestic workers as well as foreign workers, this study attempted to investigate the work burdened by musculoskeletal disorders and derive improvement measures by understanding the actual conditions of the worksites of foreign workers. The result of this investigation defines that the possibility of developing musculoskeletal disorders is very high in the environment in which more than 40% of the respondents work with heavy objects and repetitive work of wrists and elbows. To prevent the symptoms of musculoskeletal disorders among foreign workers, three measures were proposed. To reduce the mandatory check-up period of WMSD under the Occupational Safety and Health Act, to revise the employment permit system, and to enhance the practical help of EPS education. Safety and health management of foreign workers is becoming an essential task not only for securing a workforce but also for the national image. Personal and economic losses at the national level should be minimized through policy support such as financial support for small and medium-sized businesses in Korea and supplementation of legal systems for the protection of foreign workers.

• 한국안전학회지
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• 제38권1호
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• pp.70-77
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• 2023

Gas has replaced coal or petroleum as primary fuel because of its convenience. However, gas has risk of fire, explosion, or poisoning. To reduce gas-related accidents, many strategic projects have been being carried based on 'Gas Safety Management Basic Plans' on a domestic scale. In spite of those projects, the gas-related accident rate did not decrease over past decades. Thus, this study was conducted to analyze the effectiveness of ongoing projects, and to find out ways to make improvements. Conventional statistical analyses on accident data published by gas-related institutions were not useful to determine meaningful attributes to predict future. Whereas, accident case analyses adopted in the present study discovered differences in the type of people and their unsafe acts for each gas type. Meanwhile, the overall average priority of projects was not high in the aspect of System Safety Precedence. If the current trend is maintained, with sigmoid functions, it can be estimated that mean annual accident rate will decrease by only 2.0% in the next two decades. To improve the current trend, the present study made conclusions as followings: (1) safety projects should be designed with careful consideration of accident traits including gas type, unsafe acts, and persons involved and (2) alternative strategies should include system considerations such as minimum hazard design and safety devices prior to mere education or training. To summarize briefly, the present state related with gas accidents highlights the necessity of a system-based multidisciplinary approach.