• 한국화재소방학회논문지
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• 제23권1호
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• pp.55-62
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• 2009

층류영역의 분출유량에서 큰 가진강도 효과를 얻기 위해 연료관 관 공명주파수로 가진된 비예혼합 분류 화염의 일반적인 가진 연소특성을 실험적으로 조사하였다. 화염 안정화 특성에서는 두 가지 형태의 부상 특성이 존재하는 사실을 알았는데, 화염이 부상되는 가진강도 크기에서 한 쪽은 감소, 다른 영역에서는 증가하는 것으로 나타나 각각 서로 다른 부상기구가 존재함을 확인할 수 있었다. 특히 부상되지 않고 노즐에 부착된 분출유량 영역에서의 가진 연소특성을 가진 강도에 따른 화염 길이와 형상, 유동장 응답 특성 그리고 노즐 출구에서의 유속 분포를 중심으로 집중 조사하였다. 특이한 현상으로는 가진 강도 증가에 따라 화염의 신장과 in-burning 현상 그리고 화염 내 거동 와동들의 말림방향이 서로 역전되는 현상 등이 발견되었다. 노즐 출구의 유속분포와 가시화 기법을 통해 이러한 현상들이 노즐관 관벽 안쪽서부터 음의 속도가 발생하기 시작함에 따라 주변 산화제인 공기가 노즐관 안으로 유입되는 현상과 관련되는 것으로 파악되었다.

• 한국안전학회지
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• 제25권2호
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• pp.29-34
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• 2010

This paper is aimed to develop monitoring software for detecting the characteristics of current and voltage signals for series arc on electric wire. In order to attain this purpose, the characteristics of series arc were analyzed by the current and voltage signals on electric wire which were installed, and also analyzed by the changes of RMS, instantaneous of waveform value in time domain and THD in frequency domain. Monitoring program which analyze the signal was developed by Labview which can analyze in time domain and frequency domain, and save data. Experimental setup for detecting verification of monitoring program was composed loads of a lamp, an electric heater and an electric fan loads which were usually using. Measurement points for detecting verification of monitoring program were selected at both the panel board and the arc generator at the same time. As results of the experiments by monitoring program, the arc current waveform showed the same characteristic in all measurement points of all load. But the arc voltage waveform was different in each measurement point. When arc occurred, the THD of current value increased above 20%. The results of this study will be effectively used in developing the preventive system of electric fire by series arc.

• 한국화재소방학회논문지
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• 제33권2호
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• pp.132-138
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• 2019

본 연구의 목적은 소방공무원의 음주 실태를 파악하고 음주수준과 직무스트레스의 관계를 분석하기 위함이다. 연구대상은 C지역, K지역, P지역의 소방공무원 267명으로 설문을 통해 음주 실태와 직무스트레스를 측정하였다. 연구결과 음주수준은 정상음주군 152명(56.9%), 문제음주군 115명(43.1%)이었고, 음주 빈도는 2-4 회/월 83명(31.1%), 음주량은 10잔 이상 101명(37.8%), 폭음 빈도는 매일이 77명(28.8%)으로 가장 높게 나타났다. 직무스트레스가 높은 군에서 문제 음주군이 될 위험도가 높았고(OR = 5.458, 95% CI = 1.108 - 26.886), 그 중 대인관계 갈등이 음주수준에 영향을 미치는 주요 요인으로 나타났다(OR = .332, 95% CI = .134 - .820). 따라서 직무스트레스를 낮추고 대인관계 갈등을 줄인다면 음주 수준을 낮출 수 있을 것으로 기대된다.

• Design & Manufacturing
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• 제16권1호
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• pp.36-42
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• 2022

Globally, as population growth and economic development continue, resource consumption is increasing rapidly. As an alternative to electric vehicles was suggested as the environmental pollution problem emerged, the number of registered electric vehicles in Korea increased by more than 137 times compared to 2013. Secondary batteries are expected to expand into various markets such as small IT devices and electric vehicles, and the most important part of electric vehicles is the battery (secondary battery). Therefore, in this study, to analyze the stability of the CSM (Classifier Separator Mill) grinding disc that crushes secondary battery raw materials, structural analysis and vibration analysis of the 1st to 4th grinding discs and the final model were performed. The change of bending by the weight of the Grinding Disc is at least 0.065㎛ and maximum 0.075㎛, and the change by the standard gravity is judged to be very low. The strain is at least 0.00031㎛/㎛ and maximum 0.00078㎛/㎛, and even if the number of Hamer increases, the change by the weight is judged to be insignificant. When the Grinding Disc rotates at a maximum of 6000rpm, the deformation and deformation rate of the first to third models are similar, but the fourth model (Hamer 10EA) is more than three times and the final model (Hamer 12EA) is about four times. However, the maximum deformation is 28.21㎛, which is considered to be insignificant when the change is 6000rpm. Six modes of natural Frequency analysis of the 1st~4th order and final model of the grinding disc appeared to be bent or twisted.

• 지역사회간호학회지
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• 제18권4호
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• pp.643-650
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• 2007

Purpose: This study was to obtain information regarding to agricultural accidents in farm workers in the Kyungpook area. Methods: A questionnaire survey was carried out for 528 workers from the 1st to 31st of March, 2007. Frequency, percentage, mean and chi-square test with the SPSS program were used to analyze the data. Results: The causes of agricultural accidents include falling(29.0%), overseeing(18.9%), traffic accident(17.4%), putting between machinery(11.7%), crashing(5.3%), fire (0.6%) in the order of frequency. Injuries from agricultural accidents include fracture(44.7%) cerebral bleeding (10.4%), amputation(7.0%), airway obstruction (2.3%) burn(1.9%), drug addiction(1.9%) in the order of frequency. The largest proportion of the subjects of hospital treatment were in their 50s and belonged to the group of high-level economic state. Agricultural machinery collision was the most frequent cause among the subjects of hospital treatment. Conclusion: These results suggest that carelessness can be a potential risk factor for agricultural accidents in farm workers. These findings may give useful information for developing agricultural accident prevention programs for farm workers.

• 한국건축시공학회지
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• 제14권2호
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• pp.163-169
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• 2014

Engineers in the construction field have been using bonded waterproofing sheets in an attempt to resolve the imbalance in the quality, the risk of fire, safety of workers, and environmental pollution, as well as to eliminate separate use of organic adhesives on the surface of concrete. Recently, self-laminated waterproofing sheets have been developed. The purpose of this research is to find an appropriate processing speed according to the changes in physical properties, and visual observation of the waterproofing sheets laminated by the aluminum thin-film and viscosity layer that can be attached through self-adhesiveness on the surface of concrete and waterproofing sheets. Therefore, this research is conducted using a physical performance test. Based on the result of the test, when the high-frequency inductive heating apparatus was used, an improved adhesion and bonding stability effect were confirmed after the anti-hydrostatic pressure and bond strength in the temperature condition, and the surface observation in the processing speed condition.

• Steel and Composite Structures
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• 제50권4호
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• pp.375-382
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• 2024

The network theory studies interconnection between discrete objects to find about the behavior of a collection of objects. Also, nanomaterials are a collection of discrete atoms interconnected together to perform a specific task of mechanical or/and electrical type. Therefore, it is reasonable to use the network theory in the study of behavior of super-molecule in nano-scale. In the current study, we aim to examine vibrational behavior of spherical nanostructured composite with different geometrical and materials properties. In this regard, a specific shear deformation displacement theory, classical elasticity theory and analytical solution to find the natural frequency of the spherical nano-composite structure. The analytical results are validated by comparison to finite element (FE). Further, a detail comprehensive results of frequency variations are presented in terms of different parameters. It is revealed that the current methodology provides accurate results in comparison to FE results. On the other hand, different geometrical and weight fraction have influential role in determining frequency of the structure.

• 한국재난정보학회 논문집
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• 제17권4호
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• pp.667-673
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• 2021

연구목적: 본 연구는 2015년부터 5년 동안 부산광역시의 기온과 시기에 따른 119구조대의 벌집 제거 출동 경향을 분석하고자 하였다. 연구방법: 2015년 1월부터 2019년 12월까지 부산의 11개 소방서 출동 건수를 확인하고 구조 및 구급 활동의 원자료를 수집하였다. 5년간 부산광역시소방재난본부 산하 소방서의 벌집 제거 출동 건수를 파악하고, 그 결과를 바탕으로 온도와 월별, 행정구역별 벌집 제거 출동을 빈도와 백분율로 분석하였다. 연구결과: 월 평균기온이 20℃ 이상부터 출동 빈도가 증가하기 시작하여, 23℃ 이상 29℃ 미만에서 출동 빈도가 가장 높은 것으로 나타났고 월별 출동 건수 중 2017년 7,900건이 가장 높은 것으로 관찰되었다. 특히 벌집 제거 출동 시기가 해가 지날수록 빨라지는 것을 알 수 있었다. 부산광역시 행정구역별로 출동 건수를 비교한 결과, 기장군이 가장 많았으며, 해운대구, 금정구, 남구순으로 출동 빈도가 높은 것으로 나타났다. 결론: 기온 변화에 따른 벌집 제거 출동이 점차 빨라지고 있는 것을 확인할 수 있었고, 본 연구의 결과가 차후 도시 내 말벌 연구에 활용될 수 있을 것으로 여겨진다.

• 한국소음진동공학회논문집
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• 제25권4호
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• pp.291-298
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• 2015

In this study, the reverberation time of apartment living room was measured and distribution of the reverberation time was analyzed. In addition, sound field characteristics of mock-up test room similar with living room and timber structured bedroom was investigated with addition of furniture and sound absorption material. Average reverberation time of unfurnished apartment unit was 1.11 s, and reverberation time in 630 Hz~2000 Hz bands were longer than 1.2 s. It was found that from the field measurement results, reverberation time characteristic of furnished apartment living room was uniform in most of frequency bands. Averaged reverberation time of furnished living room was 0.48 s and the reverberation time of bedroom was 0.44 s. Standardized sound pressure level correction values were calculated from the average reverberation time of furnished and unfurnished apartment units. The correction value of unfurnished living room was −3.4 dB and that of furnished living room was 0.2 dB. Measured reverberation time of furnished and unfurnished apartment units indicated that reference reverberation time; 0.5 s, in KS and ISO standards is reasonable also in Korean residential environment.

• Geomechanics and Engineering
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• 제15권5호
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• pp.1125-1133
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• 2018

Real-time characterization of the rock thermal deformation and fracture process provides guidance for detecting and evaluating thermal stability of rocks. In this paper, time -frequency characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals were studied by conducting experiments during rock continuous heating. The coupling correlation between AE and EMR during rock thermal deformation and failure was analyzed, and the microcosmic mechanism of AE and EMR was theoretically analyzed. During rock continuous heating process, rocks simultaneously produce significant AE and EMR signals. These AE and EMR signals are, however, not completely synchronized, with the AE signals showing obvious fluctuation and the EMR signals increasing gradually. The sliding friction between the cracks is the main mechanism of EMR during the rock thermal deformation and fracture, and the AE is produced while the thermal cracks expanding. Both the EMR and AE monitoring methods can be applied to evaluate the thermal stability of rock in underground mines, although the mechanisms by which these signals generated are different.