• Journal of Welding and Joining
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• 제20권4호
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• pp.525-534
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• 2002

During laser spot welding of the braun tube electron gun, phenomena such as serious spattering and oxidative reaction, etc. were occurred. The spatter occurred from weld pool affects the braun tube, namely it blocks up a very small hole on the shadow mask and causes short circuit between two roles of the electron gun. We guessed that high power density and oxidative reaction are main sources of these problems. So, we studied to prevent and to reduce spatter occurring in spot welding of the braun tube electron gun using pulsed Nd:YAG laser. The characteristics of laser output power was estimated, and the loss of laser energy by optical parameter and spatter was measured by powermeter. The effects of welding parameters, laser defocused distance and incident angle, were investigated on the shape and penetration depth of the laser welded bead in flare and flange joints. From these results, the laser peak power was a major factor to control penetration depth and to occur spatter. It was found that the losses of laser energy by optic parameter and sticked spatter affect seriously laser weldability of thin sheets. The deepest penetration depth is gotten on focal position, and a "bead transition" occurred with a slight displacement of focal position relative to the workpiece surface and the absorption rate of the laser energy is affected by the shape factor of the workpiece. When we changed the incident angle of laser beam, the penetration depth was decreased a little with increasing of the incident angle, and the bead width was increased. The spattering was prevented by considering laser beam energy and incident angle.ent angle.

• 한국동물위생학회지
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• 제42권4호
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• pp.183-191
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• 2019

Claw lesion is one of the major causes of lameness in sows and the lameness is one of the reasons for culling of sows from the swine herd. This survey was conducted on sows in total of 8 farms with a total of 684 pigs. The lesions observed in the study were horizontal and vertical claw cracks (CWH & CWV), differences in the length of toes (T) and/or in the length of dew claws (DC) according to crates, breeds and parity of sows. Scores of claw lesions were assigned on 0, 1, 2, and 3 at each foot depending on the severity of the claw lesions. The sows' parity was classified into 1 to 2, 3 to 4, 5 to 8. Prevalence rate of claw lesions in sows raised on punched plastic crate was higher than that in sows raised on tribar crate. In prevlence rate by breeds, inbreed Landrace sows showed higher than that of Yorkshire sows. According to 4 claw lesions, the length of DC was the highest at parity 3~4 and CWV was the lowest at parity 3~4 in F1 crossbred sows raised on punched plastic crates, respectively. In Yorkshire breeds raised on punched plastic crates, the length of DC at parity 5~8 was the lowest and CWH was the highest at parity 3~4, respectively. In Landrace breeds raised on tribar crates, CWH was the highest at parity 1~2 and CWV was the lowest at parity 3~4, respectively. The high parity in F1 crossbred sows showed high prevalence rate of claw lesions than that of low parity and other inbreed sows, respectively. These results may be useful as elementary data in establishment of welfare quality protocol and preventive measures to reduce economic losses from craw lesions in sows.

• 한국화재소방학회논문지
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• 제16권3호
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• pp.8-11
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• 2002

전기배선계통에 있어서 접속점의 접속 접촉불량과 순간단락 시 발생하는 스파크와 열축적은 절연물의 용착과 탄화현상을 발생하여 전기화재의 주요 원인이 되고 있다. 또한 접속점의 접속·접촉불량과 순간단락 시 발생하는 전류는 일종의 써지(Surge)전류가 되어 통신, 가전제품, 컴퓨터 그리고 각종 측정기기의 소손 및 고장을 일으키며, 특히 접속점의 접속·접촉불량과 순간단락은 다양한 현상을 나타내어 안전점검시 발견이 매우 어려운 실정이다. 따라서, 본 논문에서는 누전차단기(Earth Leakage Breaker)의 보조 제어장치, 즉 전기화재예방 제어장치(Electrical Fire Prevention Control Device)를 개발하여, 상기 접속점의 접속·접촉불량과 순간 단락 시 누전차단기의 동작신뢰성을 제고시켜, 스파크와 접속점의 과열에 의한 전기화재를 예방하고자 한다.

• 전기학회논문지
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• 제61권11호
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• pp.1758-1764
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• 2012

A large number of wire rope has been used in various inderstiries as Cranes and Elevators from expanding the scale of the industrial market. But now, the management of wire rope is used as manually operated by rope replacement from over time or after the accident.It is caused to major accidents as well as economic losses and personal injury. Therefore its time to need periodic fault diagnosis of wire rope or supply of real-time monitoring system. Currently, there are several methods has been reported for fault diagnosis method of the wire rope, to find out the feature point from extracting method is becoming more common compared to time wave and model-based system. This method has implemented a deterministic modeling like the observer and neural network through considering the state of the system as a deterministic signal. However, the out-put of real system has probability characteristics, and if it is used as a current method on this system, the performance will be decreased at the real time. And if the random noise is occurred from unstable measure/experiment environment in wire rope system, diagnostic criterion becomes unclear and accuracy of diagnosis becomes blurred. Thus, more sophisticated techniques are required rather than deterministic fault diagnosis algorithm. In this paper, we developed the fault diagnosis of the wire rope using probability density estimation techniques algorithm. At first, The steady-state wire rope fault signal detection is defined as the probability model through probability distribution estimate. Wire rope defects signal is detected by a hall sensor in real-time, it is estimated by proposed probability estimation algorithm. we judge whether wire rope has defection or not using the error value from comparing two probability distribution.

• Journal of Contemporary Eastern Asia
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• 제14권2호
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• pp.69-79
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• 2015

Among public organizations, does variation in organizational structure explain variation in public managers' leadership styles (e.g., transformational and transactional leadership)? The study of leadership in public organizations is increasingly an area of scholarly interest partly sparked by movements to reform public organizations, particularly in the context of emergency management. There is, for example, a need for effective leadership that can help organizations respond to disasters (Kapucu et al. 2010; Van Wart and Kapucu 2011; Stern 2013). There are numerous documented cases where the lack of leadership skills has been linked to major social and economic losses as a result of poor disaster response (e.g., Hurricane Katrina in the U.S.). Yet, leadership is a complex concept and numerous theoretical frameworks have been developed to help explain it (Van Wart 2005). Practically speaking, the existence of different theories of leadership suggests that public managers can decide to exercise various styles of leadership. The style of leadership that a public manager exhibits matters because some styles are perceived to be more effective than others (Trottier et al. 2008). While the effects of leadership have been extensively studied, antecedents or predictors of leadership style have received little scholarly attention (Wright and Pandey 2009; Nielsen and Cleal 2011). The purpose of this research note then is to explore the potential causal relationship between the structure of an organization and the ability of a public manager to exercise transformational leadership in the context of emergency management in two Asian countries: South Korea and Japan. This research note consists of three main sections. The following section explores the relationship between leadership and organizational structure. The second section examines how certain concepts of leadership and organizational structure were applied in two case studies of disaster response. The final section presents some directions for future research.

• 한국동물위생학회지
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• 제37권3호
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• pp.151-156
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• 2014

Porcine reproductive and respiratory syndrome virus (PRRSV) causes major economic losses to the Korean pig industry. ELISA tests using recombinant nucleocapsid protein of PRRSV have been most commonly used for PRRS diagnostics. In the current study, two commercial PRRSV ELISA kits (Bionote PRRSV Antibody ELISA and IDEXX 3XR PRRS Antibody ELISA) have been compared using sera collected from 19 swine farms in various stages of PRRSV infection confirmed by professional diagnostic centers. Thus 130 sera collected from 5 different farms with active PRRSV infection, 130 sera from 6 different farms with PRRS-stabilized status, and 140 sera from 8 different farms with PRRS-free status were evaluated to determine the correlation of test results between those ELISA kits. Both ELISA kits showed a good correlation [PRRSV-positive farms ($R^2$=0.6375) and stabilized farms ($R^2$=0.8928)] in sample-to-positive (S/P) ratio va lues. Among the 140 sera from negative farms, one sample was falsely positive by either of the ELISA kits. In conclusion, both of the ELISA kits showed a good correlation when applied on field samples collected from farms at various stages of PRRSV infection. Bionote ELISA or IDEXX ELISA gave a false positive result on 1 out of 140 negative samples so their specificity was calculated as 99.3%. Therefore, Bionote ELISA would be a good complementary and alternative method for IDEXX ELISA kit, and vice versa.

• 대한수의학회지
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• 제40권4호
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• pp.707-717
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• 2000

Atropic rhinitis (AR) is one of major respiratory diseases in pigs. AR causes a great economic losses and is considered to be a multifactorial disease in which herd management, heredity, and environment. Several vaccines against have been developed commercially and used in pig farms but the efficacy of each vaccine is still questionable. In this study, one of commercial AR vaccines, which contains inactivated Bordetella bronchiseptica, Pasteurella multocida type D and their toxoid was evaluated for vaccine efficacy by challenge test. Twenty piglets were divided into four groups as follows; group I was piglets from vaccinated sows (twice before parturition); group II was piglets from vaccinated sows (same as group I) and were vaccinated at 1 day old; group III and IV were piglets without any vaccination. Groups I, II, and III were challenged by intranasal instillation of $5.3{\times}10^7$ CFU of B bronchiseptica twice and $1{\times}10^9$ CFU of P multocida five times. Group IV was control group without any vaccination and any challenge. We compared serological results, recovery rate of P multocida by polymerase chain reaction, clinical signs and pathological findings between vaccinated groups and unvaccinated groups for efficacy of the vaccine, Serological responses against B bronchiseptica and toxigenic P multocida type D were not showed evident discrepancy between vaccinated groups and unvaccinated groups assuming that the antibody responses against the vaccine is very delayed. However, growth rate, clinical signs and snout lesion grading in vaccinated groups showed more favorable than those in unvaccinated group. Therefore, AR vaccination in this study is considered to be effective in the prevention of AR in pigs.

• 상하수도학회지
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• 제23권4호
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• pp.447-458
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• 2009

Energy loss at manholes, often exceeding friction loss of pipes under surcharged flow, is considered as one of the major causes of inundation in urban areas. Therefore, it is necessary to analyze head loss at manholes, especially in case of surcharged flow. Hydraulic experiments were conducted with three cases. Case A is to test whether the shapes of the manholes influence head loss coefficients. Case B and C were proposed to further reduce head losses by improving the manhole hydraulic efficiency. In case B, the joining part of the pipe at both shapes of manholes is shifted from central part to side part. The test in case C is to check the average head loss coefficient by installing the side benching in square manhole, based on shifted joining part model. The average head loss coefficient for circular and square manhole on case A was 1.6. This did not show much difference of the head loss coefficients in spite of the discharge variation in this case. However, case B and C show large difference between head loss coefficients due to the strong oscillation of water surface and the horizontal swirl motion. The circular and square manholes in case B reduced the head loss by 30% and 6% than ones in case A, respectively. The average head loss coefficient for circular manhole in case B was 1.1. Case C reduced average loss coefficients of the square manhole in case A from 1.6 to 1.1. Accordingly, the circular manhole in case B and the square manhole in case C showed the effective way to reduce the head loss. These head loss coefficients could be available to apply to the urban sewer system with surcharged flow.

• 공업화학
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• 제24권1호
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• pp.72-76
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• 2013

본 연구에서는 norbornene 디에스터 유도체를 합성하는 공정에서 반응 부산물로 생성되는 boric acid를 회수하여 norbornene diacid의 에스터화 반응에 재사용 가능성을 조사하였다. Boric acid를 4가지의 alcohol과 에스터화 시켜 4종류의 trialkyl borate (tributyl borate, tripentyl borate, triisopentyl borate, trihexyl borate)를 합성한 다음 이를 norbornene dicarboxylic acid와 반응시키는 2단계 공정으로 디에스터 유도체를 합성하였다. 이 때 norbornene dicarboxylic acid의 전환율은 89.50~99.31%였다. 디에스터화 반응의 부산물인 boric acid를 NaCl염과 함께 회수하여 trialkyl borate를 합성한 후 정제한 결과 회수율은 92.43~99.35%이었다. 이를 다음 반응에 사용한 결과 디에스터의 수율은 43.70~64.39%였고 순도 97.70~99.24%로 수율이 일부 감소되었으나 손실이 크지 않음을 확인하였다. 주요 반응 부산물인 boric acid를 공정내에서 재사용이 가능하므로 화합물 배출에 의한 환경오염을 사전에 예방할 수 있는 친환경공정으로 적용 가능함을 확인하였다.

• 한국정보과학회논문지:정보통신
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• 제32권6호
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• pp.668-675
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• 2005

최근 무선 통신의 발달과 함께 임베디드 시스템의 성능 향상 및 보급률 증가로 기존의 분산 시스템 환경에 무선 임베디드 시스템들이 포함되기 시작하였다. 분산 시스템을 구성하늘 요소들 간의 동기화, 순서화, 그리고 일관성 유지를 위하여 시간 동기화는 반드시 필요하고, 지난 20여 년간 분산 시스템에서의 시간 동기화에 관한 많은 연구가 이루어져 왔다. 하지만 무선 임베디드 시스템에서의 시간 동기화는 메시지 지연과 손실이 많다는 점과 풍부하지 않은 시스템 자원을 고려해야 하므로, 기존 유선 환경에서 사용되었던 시간 동기화 알고리즘을 그대로 적용하기에는 어려운 점이 많다. 이에 본 논문에서는 IEEE 802.11 표준을 확장하여 무선 임베디드 환경에 적합한 시간 동기화 방법을 제안한다. 제안된 방법은 브로드캐스트 통신의 특성을 활용하여 무선 임베디드 환경에서의 제약 조건을 완화함으로써 높은 정확성을 제공하면서 메시지 손실을 감내하여 연속적인 시간 동기화를 제공할 수 있다. 이를 위해 마스터/슬레이브 방식의 구조에서 마스터는 시간 동기화를 위한 시간 정보를 브로드캐스트하고, 슬레이브는 편차와 편차율을 계산하여 마스터의 시간을 추정하고 동기화된 시간인 가상 시간을 계산하였다. 실험을 통해 제안된 시간 동기화 알고리즘을 사용하는 경우 200${\mu}s$ 정도의 표준 편차 범위로 동기화할 수 있음을 보였다.