Spatial risk factors of the 2016 to 2018 highly pathogenic avian influenza epidemics in the Republic of Korea

김으뜸(Eu-Tteum Kim),박선일(Son-Il Pak) 한국예방수의학회 2020 예방수의학회지 Vol.44 No.4

The current study explored the epidemiological associations between the 2016/18 highly pathogenic avian influenza (HPAI) epidemics and spatial factors, including the distance from a poultry farm to the closest groundwater source, migratory bird habitat, eco-natural area, and poultry farm altitude. We included 14 spatial factors as independent variables. The variables were used in the original continuous measurement format. In total, 288 poultry farms (144 HPAI-confirmed and 144 non-confirmed) were used as the dependent variable. In addition, the variables’ continuous measurement was converted to a categorical measurement format by using a general additive model. For risk factor analysis based on the continuous measurements of spatial factors, the non-graded eco-natural area distance (odds ratio [OR]: 1.00) and the grade one eco-natural area distance (OR: 0.99) were statistically significant independent variables. However, in the risk factor analysis based on the categorical measurement format of the spatial factors, the non-graded eco-natural area distance (OR: 0.08) and poultry farm altitude (OR: 0.44) were statistically significant independent variables in both a univariate and multiple logistic regression model. In other words, when a poultry farm was located far from the non-graded eco-natural area or in a highland area, the likelihood of an HPAI epidemic would decrease. From an HPAI control perspective, it is recommended that the government apply increased levels of biosecurity measures, such as bird-nets, fences, intensive disinfection of equipment, and regular bird health monitoring, for poultry farms located near non-graded eco-natural areas or in a lowland area.

Movement characteristics of 14 migratory bird species wintering in the Republic of Korea between 2014 and 2020

김으뜸(Eu-Tteum Kim),장국렬(Kug-Lyoul Jang),곽연숙(Yeon-Sook Kwak),이호성(Ho-Sung Lee),박선일(Son-Il Pak) 한국예방수의학회 2020 예방수의학회지 Vol.44 No.4

The current study explored the movement characteristics of 14 migratory bird species that wintered in the Republic of Korea between 2014 and 2020. The migratory bird movement information was obtained via a global positioning system operated by the Korean government. The velocity of movement, number of clusters, and size of clusters of the migratory bird species during their movement from their departing country to the Republic of Korea were estimated by applying a method based on density-based spatial clustering of applications with noise. The average movement velocity of pintails (Anas acuta) that departed from China or Russia was 32.77 km/h, the highest velocity among those measured for the 14 migratory bird species. The average number of clusters for cinereous vultures (Aegypius monachus) was 43.00, which was the largest cluster number observed. However, herring gulls (Larus argentatus) had the largest cluster area with an average cluster radius of 27.43 km while wintering in the Republic of Korea. The findings of the current study could be useful in increasing the effectiveness of the Korean national highly pathogenic avian influenza (HPAI) surveillance program. The human and material resources of the HPAI surveillance could be allocated after considering the results of this study, revealing the movement characteristics of wintering migratory birds in Korea. The HPAI surveillance program should include fecal or swab sampling to detect the HPAI virus in both pintail and bean goose (Anser faballis) wintering sites. Sampling of those sites should have a higher priority than that for other migratory bird wintering sites since pintail and bean goose move faster and form larger clusters.

섬유금속적층판의 모드 I 접합 거동 예측을 위한 Levenberg-Marquardt 기법 기반의 역해석 기법에 관한 수치적 연구

박으뜸 ( Eu-tteum Park ),이영헌 ( Youngheon Lee ),김정 ( Jeong Kim ),강범수 ( Beom-soo Kang ),송우진 ( Woojin Song ) 한국복합재료학회 2018 Composites research Vol.31 No.5

섬유금속적층판은 금속과 섬유 강화 복합소재를 함께 적층한 하이브리드 재료 중 하나다. 섬유금속적층판은 계면의 접착층이 파괴되는 층간분리 현상이 발생할 수 있기 때문에 계면의 접착층에 대한 한계응력과 에너지 해방률을 실험적으로 도출해야만 한다. 하지만, 온도에 따른 에너지 해방률을 실험적으로 도출하는 과정에서 측정 장비의 사용 온도에 대한 제약을 받는다. 따라서, 본 연구에서는 Levenberg-Marquardt 기법을 기반한 역해석기법을 사용하여 접착층에 대한 모드 I 한계응력과 에너지 해방률에 대한 예측 가능성을 확인하는 것이 목표다. 먼저, 한계응력은 접착층의 인장강도와 같다고 가정하였으며, 에너지 해방률은 DCB 시험(double cantilever beamtest)을 수행하여 정의하였다. 또한, 유한요소법 기반 모델을 적용하여 한계응력과 에너지 해방률을 수치해석적으로 예측할 수 있는 지 확인하였다. 그 후, Levenberg-Marquardt 기법을 유한요소법 기반 모델에 적용하여 모드 I 한계응력과 에너지 해방률을 수치해석적으로 예측하였다. 아울러, 본 연구에서 사용한 역해석 기법의 수렴성을 확보하기 위하여 두 가지 경우의 초기 매개변수에 대한 역해석을 추가적으로 수행하였다. 결과적으로, 본 연구에서 사용한 역해석 기법은 모드 I 한계응력과 에너지 해방률을 효과적으로 예측할 수 있음을 보였다. Fiber metal laminate (FML) is a type of hybrid composites which consist of metallic and fiber-reinforced plastic sheets. As the FML has a drawback of the delamination that is a failure of the interfacial adhesive layer, the nominal stresses and the energy release rates should be determined to identify the delamination behavior. However, it is difficult to derive the nominal stresses and the energy release rates since the operating temperature of the equipment is restricted. For this reason, the objective of this paper is to predict the mode-I nominal stress and the mode-I energy release rate of the adhesive layer using the inverse analysis based on the Levenberg-Marquardt method. First, the mode-I nominal stress was assumed as the tensile strength of the adhesive layer, and the mode-I energy release rate was obtained from the double cantilever beam test. Next, the finite element method was applied to predict the mode-I delamination behavior. Finally, the mode-I nominal stress and the mode-I energy release rate were predicted by the inverse analysis. In addition, the convergence of the parameters was validated by trying to input two cases of the initial parameters. Consequently, it is noted that the inverse analysis can predict the mode-I delamination behavior, and the two input parameters were converged to similar values.

국내 돼지오제스키병의 혈청학적 감시활동(surveillance)을 위한 표본크기

김으뜸,박선일,박최규,권창희,Kim, Eu-Tteum,Pak, Son-Il,Park, Choi-Kyu,Kweon, Chang-Hee 대한수의학회 2007 大韓獸醫學會誌 Vol.47 No.4

Serological surveillance programs in animal populations are becoming increasingly important to estimate prevalence of a specific disease and subsequently to document disease-free status in a region or a country. For these purposes, the programs need to be based on both theoretical and economical aspects from the designing phase. From Aujeszky's disease (AD)-eradication program point of view, group of animals (aggregates, herds) not individual animal is the more important sampling unit of concern. In this study the authors therefore attempted to compute an appropriate sample size tailored to a current surveillance program against AD, assuming that the goal of this program is either herd-level prevalence estimation or documentation of AD-freedom. For prevalence estimation, assuming a finite population with imperfect sensitivity (Se) and specificity (Sp) of ELISA kit for AD diagnosis, the number of herds present, expected herd prevalence, and desired accuracy for a certain level of confidence, sample size was estimated at herd-level in the first stage and individual animal-level in the second stage. A two-stage sampling design was used to calculate a sample size to indicate AD-freedom. In this instance, the computation was based on the possible detection of a predetermined prevalence at a certain herd-level Se and Sp. This study indicated that the sample size varied with predetermined confidence, tolerance, Se and Sp at herd- and animal-level, and within- and among-herd prevalence. In general, smaller sample size was required to estimate AD prevalence than to document of AD-freedom. Compared to individual-based samples, two-stage sampling strategy requires a larger sample size to show disease-freedom. Statistical considerations including herd-level test characteristics when designing surveillance program also are further discussed.

자동차 측면 도어의 섬유금속적층판을 적용한 임펙트 빔의 수치해석에 의한 성능 평가

박으뜸 ( Eu-tteum Park ),김정 ( Jeong Kim ),강범수 ( Beom-soo Kang ),송우진 ( Woo-jin Song ) 한국복합재료학회 2017 Composites research Vol.30 No.2

섬유금속적층판은 금속 판재와 섬유 강화 플라스틱을 적층한 하이브리드 소재 중 하나다. 섬유금속적층판은 부품 경량화 측면을 고려했을 시, 뛰어난 충격흡수능력을 가지고 있기 때문에 자동차 및 항공우주 산업에서 적용 및 연구를 진행하고 있는 추세다. 특히, 자동차의 측면 도어 임펙트 빔의 경우, 기존의 금속소재에서 복합재료로 대체하기 위한 연구가 활발히 진행 중이다. 본 연구에서는 자동차의 측면 도어 임펙트 빔을 금속소재와 자기 강화형 폴리프로필렌을 적층한 섬유금속적층판으로 대체하는 것이 목표다. 3가지 종류의 임펙트 빔의 3점 굽힘 시험 수치해석을 통해 단면적 대비 굽힘 저항력의 크기를 비교하였다. 그 후, 제작 실현성을 고려하여 굽힘 저항력이 우수한 이중모자형 임펙트 빔을 순수 DP 980과 섬유금속적층판으로 제작하여 자동차 측면 도어에 설치된 모델을 상정하고 충돌 해석을 수행하였다. 결과적으로 섬유금속적층판을 사용한 임펙트 빔은 기존의 DP 980보다 무게 대비 충격 에너지 흡수 능력이 약 7배 높음을 알 수 있었다. The fiber metal laminate is a type of hybrid materials laminated thin metallic sheets with fiber reinforced plastic sheets. The laminate has been researched or applied in automotive and aerospace industries due to their outstanding impact absorbing performance in view of light weight aspect. Specially, the replacement of side-impact beam as the fiber reinforced plastic has been researched actively. The objective of this paper is the primitive investigation in the development of side-door impact beam using the fiber metal laminate. First, the three-point bending simulations were conducted to decide the shape of impact beam using the numerical analysis. Next, two cases impact beam (pure DP 980 and fiber metal laminate) were installed in the side-door, and then the bending tests (according to FMVSS 214S) were simulated using the numerical analysis. It is noted that the side-door impact beam can be replaced with the fiber metal laminate sufficiently based on the numerical analysis results.

Home range of mallard (Anas platyrhynchos) and spot-billed duck (Anas poecilorhyncha) during the 2014/15 highly pathogenic avian influenza epidemics in the Republic of Korea

김으뜸(Eu-Tteum Kim),조형우(Hyeong-Woo Cho),박선일(Son-Il Pak) 한국예방수의학회 2021 예방수의학회지 Vol.45 No.4

The mallard and spot-billed duck are representative migratory bird species wintering in the Republic of Korea. They can be a highly pathogenic avian influenza (HPAI) virus carrier during their wintering movement. From September 2014 to June 2015, 162 poultry farms were confirmed to have a HPAI infection. The current study estimated the home range of the mallard and spot-billed duck during the 2014/15 HPAI epidemics to explore the relationship between the wintering site of the migratory birds and the geographical locations of HPAI-infected farms. A Brownian bridge movement model was applied to estimate the home ranges of 13 mallards and three spot-billed ducks. As a result, 22 HPAI-infected poultry farms were located geographically in the 99% cumulative probability contour of the home range of the mallard, but no HPAI-infected poultry farm was found in spot-billed duck’s home range. In the case of one spot-billed duck, however, it has two wintering sites: Chungcheongnam-do and Jeollanam-do. Considering that migratory birds can be a major driven factor in HPAI virus transmission from wild birds to poultry farms, it is recommended for poultry farms located within the home range of migratory birds to increase their biosecurity level during wintering season of migratory birds.

열가소성 복합재료를 기반한 섬유금속적층판의 충격 거동에 관한 실험 및 수치적 연구

이병언(Byoung-Eon Lee),강동식(Dong-Sik Kang),박으뜸(Eu-Tteum Park),김정(Jeong Kim),강범수(Beom-Soo Kang),송우진(Woo-Jin Song) 한국자동차공학회 2016 한국 자동차공학회논문집 Vol.24 No.5

Population viability analysis to estimate the needed number of capture-and-remove wild boars for control of African swine fever in the Republic of Korea

조희경(Hee-Kyeung Cho),정봉수(Bong-Su Jung),정충식(Chung-Sik Jung),박선일(Son-Il Pak),김으뜸(Eu-Tteum Kim) 한국예방수의학회 2020 예방수의학회지 Vol.44 No.4

Since the first detection of the African swine fever (ASF) virus in the Republic of Korea in 2019, the Korean government has applied interventions, including fencing, increasing the biosecurity level at domestic pig farms, and the capture-and-removal of wild boars. In particular, wild boars are an important risk factor for ASF control because they can spread disease among susceptible animals, such as wild boars or domestic pigs. A capture-and-removal method aims to reduce the likelihood of ASF transmission from wild boars to domestic boars or among wild boars by decreasing the number of susceptible wild boars. This study estimated the required number of wild boars captured and removed for ASF control using population viability analysis. Population factors, such as a life span, sex ratio, or an inbreeding depression with different capture-and-removal proportions of wild boars, were included in the analysis. Ten scenarios with different capture-and-removal proportions of wild boars and different periods of culling were considered. According to the results, a method in which 75% of wild boars are captured-and-removed for at least three years showed long-term effectiveness for more than ten years. The current ASF control method, in which 33% of wild boars are captured-and-removed, decreased the number of wild boars for three years, after which the wild boar population increased to more than its initial number. Given the limited human and material resources for controlling ASF in the Republic of Korea, it is recommended that resources be prioritized to increase the capture-and-removal proportion of wild boars to take full advantage of the ASF-control effectiveness.