• 한국전산구조공학회논문집
• /
• 제20권5호
• /
• pp.641-652
• /
• 2007

본 논문에서는 풍하중에 대한 기존 송전철탑의 좌굴 및 구조적 안전성을 평가하기 위해서 축소부분구조 실험을 수행하였다. 원 송전철탑에 작용하는 중력 및 풍하중을 재현하기 위해서 1/2크기의 상사법칙을 적용한 축소모델의 상부에 설치된 삼각형태의 지그를 이용하여 가력하는 방법을 고안하였다. 설계하중에 대한 실험체의 안정성을 평가하기 위해서 예비수치 해석을 수행한 결과, 계산된 주주재의 축력은 허용좌굴하중의 $80{\sim}90%$사이에 분포하고 있음을 확인하였다. 최대허용좌굴 하중의 270%까지 가력한 결과, 주주재의 면외거동을 구속하는데 취약한 절점에서 발생한 국부좌굴로 인하여 송전철탑이 파괴되었다. 하중-변위 곡선, 변위, 부재별 변형률을 검토한 결과, 이러한 국부좌굴의 발생은 동일한 단면내에서도 휨모멘트로 인해 항복응력에 도달하는 시간이 위치별로 다르기 때문에 변형의 불균형에 의해서 발생한 부가적인 편심에 기인한 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권7호
• /
• pp.1026-1034
• /
• 2000

As described here, most recently developed methods for improving reproduction performance of domesticated animals such as cattle, swine and chicken have been considered to be also usable for restoring some sorts of endangered and/or extinct wild animals in the very near future. Especially, the techniques for in vitro storage of gametes obtained from dead animals shortly after the death, probably 24 h following the sacrifice are also available for obtaining some of experimental specimens. In case of the endangered animals, nobody will be allowed to use any tissues from the living animals, therefore, e.g., the use of skin tissues from these bodies is another possibility of restoring the living animals. Regarding the use of skin tissues, the most highly usable tools must be the cloning techniques for reviving rare cells from the living body. Most possible techniques for cloning cells is nuclear transfer from rare species to highly relative species, and this is the case of germ cells, e.g., primordial germ cells (PGCs) of avian species. One of the possibilities is the nuclear transfer of Crested Ibis (Nipponia nippon) to the PGCs of chicken, resulting in the PGCs with transferred nucleus from the ibis. In mammalian species, the same procedure as in the case of birds would be successful, e.g., the removed nucleus from Giant Pandas will be transferred to the cell, such as somatic cells or germ cells from black bears or lesser pandas, leading to the production of transnucleared cells in the body of female black bears. These two cases are most promising techniques for reviving endangered animals in the world, particularly in Asian countries, mainly in China. As a conclusion, possible production of cloned animals carrying transnucleared cells from endangered animals, such as Giant Pandas and Crested Ibis, may be reproduced gradually in the near future. Scientists are, therefore, required to convert the paradigm from domestic animals to wild animals, including endangered and/or extinct animals on the earth.

• Journal of Biosystems Engineering
• /
• 제25권6호
• /
• pp.457-462
• /
• 2000

Boom sprayers have been known by their excellency in field efficiency worker’s safety and pest control efficacy. The boom sprayer in Korea that was developed for paddy field is not suitable for upland field of which shape is irregular and inclination is steep, due to heavy chemical tank long boom width and manual on-off control of spraying. The goal of the study was to develope a boom control system that could control boom angles of left and right boom automatically and independently corresponding to local field slope. The prime mover was selected as a cultivating tractor. Main results of this study were as follows. 1. Ultrasonic sensor whose response time was 0.1s and response angle was within $\pm$20$^{\circ}$was selected to measure distance. Voltage output of the sensor(X, Volt) had a highly significant linear relationship with the vertical distance between the sensor and ground surface(Y, mm) as follows; Y=0.0036X-0.437 2. Left and right section of the boom could be folded up by a position control device(on-off control) which could control the left and right boom independently corresponding to local slope by equalizing distances between the sensor and boom at the center and left/right boom. Most reliable DB(dead band) was experimentally selected to be 75$\Omega$(6cm). 3. At traveling velocity of 0.3~0.5m/s RMS of error between desired and achieved height was less than 4.5cm The developed boom angle controller and boom linkage system were evaluated to be successful in achieving the height control accuracy target of $\pm$10cm.

• 한국강구조학회 논문집
• /
• 제15권5호통권66호
• /
• pp.489-497
• /
• 2003

사회적 환경에 따른 교량의 장대화와 단순화의 추세로 인해 구조적 시스템과 생명주기에서 교량 건설의 경제적 효율성이 증대되고 있다. 강교 제작의 경제성과 효율성을 위해 시공 전 상세한 구조해석이 실시되어져야 하며 특히 강상자형교에서는 지점부 다이아프램과 수직보강재가 초점이 되는 주요 부재중의 하나이다. 본 논문에서는 강상자형교를 시공하거나 확장, 보수하는 과정에서 일어나는 추가 사하중에 대하여 지점부의 다이아프램 거동 분석을 위해 실측과 구조해석을 통시에 수행하여 다이아프램부 응력 분배 거동을 분석하고 다이아프램 수각보강 재의 적절한 길이를 제안하고자 하였다.

• 한국임상수의학회지
• /
• 제26권5호
• /
• pp.467-471
• /
• 2009

This report describes Neural Tube Defects (NTDs) with Abdominal Wall Defects (AWDs) on the sibling of Yorkshire terriers. The NTDs and AWDs are rare serious congenital defects. The NTDs are neurulation abnormality that results from to failed transformation of the neurual tube by the incomplete closure of the embryonic neural plate. These dysraphic states range form mild to severe according to developmental malformation that include fusion defects of skull (crania bifida; CB) and fusion defects of vertebrae (spina bifida; SB). The AWDs are genetic defects that results from to failed formation of abdominal wall and cavity. These dysraphic states are omphalocele and gastroschisis. The 12-month dam was delivered by caesarian section and 4 littermate had obvious malformations. One male dead stillbirth fetus (L1) was revealed the extruded abdominal viscera, omphalocele. One female fetus (L2) was died within 1 hour after birth with defects of abdominal muscle upper umbilicus, gastroschisis. 3rd fetus (L3) was died within 36 hours after parturition and revealed a copious dermal and vertebral defects on the midline thorax, upper SB asperta. 4th fetus (L4) is still growing well now at 6 months but at the 2 week age, appears hairy nevus on the frontal cranium and dorsal thoracic portion. The radiograph of L1 and L2 are shown decrease bony density of calvarium and L3 was shown defect of spinose processes of the T9-T13. On our knowledge, this is first report of the SB and CB in Yorkshire terrier. And also sibling of NTDs with AWDs that has not previously been reported in the dog.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 추계학술대회 논문집
• /
• pp.1171-1176
• /
• 2005

The latest technical development of steel plate girder railway bridge are developing in ways to maximize its durability of materials in use of high strength steel and efficiency of maintenance and management by the introduction of simplified and standardization ideas. In addition to this, it is also expected to reduce the cost of bridge construction and to simplify the process of bridge manufacturing. Referring to this, composite few plate girder railway bridge is highly recommendable that is very economical with the fine exterior. In this paper, it will analyse the variation of dynamic behavior of existing composite few plate girder railway bridge with ballast caused by modified Slab Track through interpretation of limited enzyme in order to obtain the existing data for improvement of Slab Track system from Ballast Track system. Consequently, it can help maximize economic efficiency and structural capability. As a results, although the natural frequency by modified Slab Track are decreased, it is hardly influencing on the safety of railway bridges. It is also evident in the case of slab deck with a reduced scale in comparison with Ballast Track. Therefore, it is expected to reduce the cost of a railway bridge plan. And, it can expect the synergistic effect of the ensure long term durability of bridge caused by decreased stresses of bottom flange due to reduced dead load. As a result, the analytical study are carried out to investigate the composite few plate girder railway bridge could be the optimal design method for the dynamic safety of a girder section.

• Steel and Composite Structures
• /
• 제32권1호
• /
• pp.1-19
• /
• 2019

The aim of the paper is the prediction of the seismic collapse mode of steel storage pallet racks under seismic loads. The attention paid by the researchers on the behaviour of the industrial steel storage pallets racks is increased over the years thanks to their high dead-to-live load ratio. In fact, these structures, generally made by cold-formed thin-walled profiles, present very low structural costs but can support large and expensive loads. The paper presents a prediction of the seismic collapse modes of multi-storey racks. The analysis of the possible collapse modes has been made by an approach based on the kinematic theorem of plastic collapse extended to the second order effects by means of the concept of collapse mechanism equilibrium curve. In this way, the dissipative behaviour of racks is determined with a simpler method than the pushover analysis. Parametric analyses have been performed on 24 racks, differing for the geometric layout and cross-section of the components, designed in according to the EN16618 and EN15512 requirements. The obtained results have highlighted that, in all the considered cases, the global collapse mechanism, that is the safest one, never develops, leading to a dangerous situation that must be avoided to preserve the structure during a seismic event. Although the studied racks follow all the codes prescriptions, the development of a dissipative collapse mechanism is not achieved. In addition, also the variability of load distribution has been considered, reflecting the different pallet positions assumed during the in-service life of the racks, to point out its influence on the collapse mechanism. The information carried out from the paper can be very useful for designers and manufacturers because it allows to better understand the racks behaviour in seismic load condition.

• Steel and Composite Structures
• /
• 제39권1호
• /
• pp.65-80
• /
• 2021

Irregularities of a building in plan and elevation, which results in the change in stiffness on different floors highly affect the seismic performance and resistance of a structure. This study motivated to investigate the seismic responses of high-rise steel-frame buildings of twelve stories with various stiffness irregularities. The building has five spans of 3200 mm distance in both X- and Z-directions in the plan. The design package SAP2000 was adopted for the design of beams and columns and resulted in the profile IPE500 for the beams of all floors and box sections for columns. The column cross-section dimensions vary concerning the number of the story; one to three: 0.50×0.50×0.05m, four to seven: 0.45×0.45×0.05 m, and eight to twelve: 0.40×0.40×0.05 m. Real recorded ground accelerations obtained from the Vrancea earthquake in Romania together with dead and live loads corresponding to each story were considered for the applied load. The model was validated by comparing the results of the current method and literature considering a three-bay steel moment-resisting frame of eight-story height subject to seismic load. To investigate the seismic performance of the buildings, the time-history analysis was performed using ABAQUS. Deformed shapes corresponding to negative and positive peaks were provided followed by the story drifts and fragility curves which were used to examine the probability of collapse of the building. From the results, it was concluded that regular buildings provided a seismic performance much better than irregular buildings. Furthermore, it was observed that building with torsional irregularity was more vulnerable to seismic failure.

• 한국축산시설환경학회지
• /
• 제18권1호
• /
• pp.1-8
• /
• 2012

돈사의 피상부(皮上部) 환경개선을 위한 본 연구에서는 경기도 용인군에 위치한 형제농장의 비육돈사를 실험축사로 선정하여, 외부환경에 따른 돈사환경의 변화, 실내 공기유동을 위한 팬의 유무 등이 실내환경에 미치는 영향을 살펴보았다. 그 결과 다음과 같은 결론을 얻을 수 있었다. 1. 외기온이 $25.7^{\circ}C$인 실험 1의 경우 측벽 윈치커튼을 통하여 유입된 공기는 용마루(ridge)의 윈치커튼를 통하여 배출되었으며, 중앙단연의 속도가 바닥부근 유속의 2~3 배에 이르는 것은 열부력(thermal buoyancy) 때문에 공기유동이 에너지를 얻어 유속이 가속되었으며, 측벽 윈칙커튼으로 유입된 공기유동은 급격히 확산되어 소산(消散)(disssipation)되었다. 그러므로 윈치커튼 돈사의 경우, 외부 바람의 속도가 거의 없거나 있어도 속도가 적다면, 돈사내 공기유동의 형태는 주로 열부력에 의하여 결정됨을 알 수 있다. 2. 실험 1에서는 비교적 균일한 온도분포를 보이고 있으나 실내온도가 외부에 비하여 전반적으로 외기온 보다 높게 나타났으며, 이는 돼지의 현열 및 배출분뇨에 의한 바닥층의 부숙열이 피상부(皮上部) 공간의 현열접적을 환기로 적절히 제거시키지 못한 결과로 판단된다. 따라서 실내에서 발생되는 열을 효과적으로 제거하기 위하여서는 강제환기 시설 또는 측벽 및 용마루 윈치커튼의 개폐정도 등을 포함한 관리논리를 개발할 필요하다. 3. 실험 2는 실험 1과 같이 외기온이 $25.7^{\circ}C$로 비슷하나 복사열의 영향여부를 실험 1과 비교검정하기 위하여 흐린 날을 선택하고 돈사내 강제환기를 위한 팬을 작동시킨 상태에서 중앙단면에서의 유속을 측정한 결과 실험 1에 비해 속도가 대체로 크나, 편차 또한 크게 나타났으며, 팬 작동시 공기유동의 정체지역(dead region)이 발생한 것을 알 수 있었다. 따라서 강제환기시에는 보다 정확한 환기율을 결정하고 설계 시공이 필요할 것으로 판단된다. 또한 바람이 없고 외기온이 매우 높은 여름철에는 열집적을 효과적으로 희석시키기 위해서 연속적인 강제환기가 필요할 것으로 판단된다. 4. 실험 2에서의 유해기체의 농도를 실험 1과 비교해 보면 전체적으로는 편차가 적게 나타났으며, 외부기상의 차이로 인해 암모니아의 농도는 실험 1에 비해서 매우 높게 나타났다. 이는 외부기상에 따른 실내공기 유동의 효율저하, 상대습도의 변화 등으로 판단되며, 외기상의 변화에 능동적으로 대처할 수 있는 환기시스템의 개발도 고려해볼 필요가 있다. 5. 실험 2에서의 온도분포는 거의 편차가 없이 균일하게 나타난 것을 볼 수 있었으며, 비로 인하여 지붕이 받는 부가적인 태양복사열이 없었으며, 실험 1과는 달리 열부력에 의한 상고하저(上高下低)의 전형적인 수직분포가 나타나지 않고, 오히려 지붕을 냉각시키는 효과를 가져와 상저하고(上低下高)의 분포를 나타냈으며, 수평온도분포도 팬에 의한 강제환기에 의해 실내공기를 균일하게 분포시켜 거의 편차가 없음을 알 수 있었다. 그러므로 지붕의 단열이 축사환경제어에 중요한 변수로 작용한다는 것을 알았으며, 이를 위해서 지붕의 단열 및 높이 등의 설계가 매우 중요하다.

• Reproductive and Developmental Biology
• /
• 제32권1호
• /
• pp.51-58
• /
• 2008

본 연구는 체세포 복제 한우 송아지의 생산에서 생시체중과 생존성과의 관계에 대하여 살펴보고자 실시하였다. 293두의 한우 대리모에 580개의 복제란을 이식하였다. 복제란의 임신율은 이식 후 50일까지 72.3%로 높았으나, 이후 급격하게 감소하였다. 평균 임신 기간은 복제 송아지에서 287일($279{\sim}295$일)이었으며, 인공수정 송아지도 287일($255{\sim}293$일)로 각각 나타났다. 복제 송아지의 생시체중(30.3kg)은 인공수정 송아지(23.7kg)에 비하여 유의하게 높은 것으로 나타났다(p<0.05). 자연분만(n=17, 29.9kg)과 제왕절개(n=14, 32.3kg)로 태어난 복제 송아지의 생시체중은 차이가 없었다. 하지만, 생후 175일 이전에 사망한 복제 송아지(n=18, 32.8kg)의 생시체중이 175일 이상 생존한 복제 송아지(n=11, 28.3kg)보다 유의적으로 높게 나타났다(p<0.05). 흥미로운 점은 생시체중이 15kg 이하(n=5) 또는 35kg 이상(n=9)인 복제 송아지들은 모두 생후 175일 이전에 폐사하였다. 생후 175일 이전에 폐사한 복제 송아지들(n=20)의 사망 원인은 미성숙 개체 2두(10.0%), 폐와 간 이상 2두(10.0%), 폐의 원인 4두(20.0%), 기형 4두(20.0%), 출생 후 급사(sudden death syndrome) 4두(20.0%) 및 기타 원인불명이 4두(20.0%) 등으로 분류되었다. 이상의 결과를 종합하여보면, 복제 송아지의 정상 생시체중이 6개월 이상을 생존하는데 가장 중요한 요소들 중의 한 가지임을 확인하였다.