• Structural Engineering and Mechanics
• /
• 제23권2호
• /
• pp.177-193
• /
• 2006

Determining the hysteretic energy demand and dissipation capacity and level of damage of the structure to a predefined earthquake ground motion is a highly non-linear problem and is one of the questions involved in predicting the structure's response for low-performance levels (life safe, near collapse, collapse) in performance-based earthquake resistant design. Neural Network (NN) analysis offers an alternative approach for investigation of non-linear relationships in engineering problems. The results of NN yield a more realistic and accurate prediction. A NN model can help the engineer to predict the seismic performance of the structure and to design the structural elements, even when there is not adequate information at the early stages of the design process. The principal aim of this study is to develop and test multi-layered feedforward NNs trained with the back-propagation algorithm to model the non-linear relationship between the structural and ground motion parameters and the hysteretic energy demand in steel moment resisting frames. The approach adapted in this study was shown to be capable of providing accurate estimates of hysteretic energy demand by using the six design parameters.

• 한국초전도ㆍ저온공학회논문지
• /
• 제7권3호
• /
• pp.1-4
• /
• 2005

As high temperature superconductor applications became a reality due to increase in coated conductor performance, it is important to understand their stability behavior to design safe electrical power systems. Coated conductors can be stabilized with different metals and alloys for different types of application, to yield excellent electrical, thermal and mechanical performance. We have experimentally studied the dependence of quench and recovery characteristics of stainless steel stabilized coated conductors on the amplitude of current and duration time. Stability test of 3cm long sample were performed in a liquid nitrogen bath cooling condition by applying a short period over current pulses for 50 and 100ms, with amplitude up to ~6 times the critical current. The transport current that flows before and after the current pulse was fixed at about ~80-85% critical current. We analyzed the quench and recovery phenomena of the test sample using the current voltage characteristic.

• 한국작물학회지
• /
• 제40권5호
• /
• pp.562-568
• /
• 1995

본 시험은 벼 만기기 및 보리후작 건답직파의 수량성과 토양 화학성 변화에 대한 기초 자료를 얻고자 영남농업시험장 답작포장에서 1990년부터 1994년까지 5년간 시험을 수행하였다. 공시품종은 일본형인 동해벼를 사용하였고, 작촌방식은 벼 단작 면기직파와 보리후작 벼 직파로 하였고, 보리 후작 벼 직파는 보릿짚 제거후 직파와 보릿짚 시용후 직파로 하여 실시하였던 시험 결과를 요약하면 다음과 같다. 1. 보리후작 건답직파도 $m^2$당 적정 입모수 확보는 문제가 없었으나 연차간 입모 변이는 컸었고, 벼 단작 직파에 비하여 초기 묘생육은 약간 떨어졌으나 점차 생육이 회복되어 최종 벼 생육은 벼 단작 직파보다 좋았다. 2. 보리후작 벼 직파시 휴립건답직파 방식은 벼 단작 직파와 출수기 차이가 없었으나 평면 건답 직파에서는 출수기가 4일이 늦었다. 3. 수량구성요소중 천립중 및 등숙비율은 작촌양식간 비슷하였으나, $m^2$당 수수 및 영화수는 보리 작후 벼 직파에서 많았다. 4. 쌀 수량은 보릿짚제거후 벼 직파는 벼 단작 직파와 비슷하였으나 보릿짚 시용후 벼 직파에서는 2년차부터 쌀 수량이 증수되어 5년 평균 쌀 수량은 벼 단작 대비 8% 증수되었다. 5. 5년간 장기 건답직파시 토양 유기물 함량은 벼 단작구는 떨어졌으나 보리후작 직파구는 증대되었고, 작촌방식별 다같이 칼리함량은 비슷했으나, 인산과 칼슘함량은 증대되었고 마그네슘함량은 약간 떨어지는 경향이었다. 6. 작촌방식별 현미 품위, 아밀로스 및 단백질함량은 별 차이가 없었고, 칼리, 마그네슘함량 및 Mg/K는 보릿짚 시용후 벼 직파에서 낮았다.

• 한국농림기상학회지
• /
• 제20권2호
• /
• pp.190-204
• /
• 2018

본 연구는 북한 27개 기상 관측 지점의 1981~2016년 기온 자료에 벼 주요 생육 단계의 기준 온도를 적용하여 지역별 벼 안전 재배 가능성을 분석하고 각 지역의 기온에 적합한 재배 시기를 설정하기 위하여 수행하였다. 벼 안전 재배 가능 햇수 비율은 개성, 해주, 용연, 신계, 사리원, 남포, 평양, 안주, 구성, 신의주, 장전, 원산, 남포, 평강, 희천, 수풍, 강계의 17 지역에서 90% 이상이었고, 양덕과 신포의 2개 지역에서 80~90%로 벼 재배의 안전성이 높았다. 김책, 청진, 선봉, 중강, 장진, 풍산, 혜산, 삼지연의 8개 지역은 벼안전 재배 가능 햇수의 비율이 80% 미만으로 재배 안전성이 상대적으로 낮게 평가되었다. 특히 북부 고산 지대에 속하는 4개 지역에서는 안전 재배 가능 연도가 한 해도 출현하지 않았으며, 동해안 북부 지대의 선봉에서는 16%로 낮아 벼 안전 재배가 어려울 것으로 분석되었다. 지역에 따라 안전 조기 이앙 한계기는 사리원의 5월 4일~신포의 5월 24일, 안전 출수기는 강계의 7월 21일~해주의 8월 11일, 수확 한계기는 강계의 9월 17일~해주와 장전의 10월 16일 범위였다. 안전 조기 이앙 한계기~안전 출수기 기간은 양덕에서 67일로 가장 짧았고, 해주에서 97일로 가장 길었다. 안전 출수기~안전 수확 한계기 기간은 양덕, 희천, 강계에서 60일 미만으로 짧았고, 장전과 원산에서 70일 이상으로 길었다. 본 연구는 북한 지역별 평균기온에 근거하여 벼 재배 지역의 안전 생육 시기와 기간을 분석하였고, 지역별 강수량과 같은 다른 기상 요소는 고려하지 않았으며, 생산성까지는 추정하지 못하였다. 그러나 북한의 지역별 벼 재배를 위한 기본 정보를 제공할 수 있을 것으로 기대하며, 생산성 모의나 북한 적응 기술에 대한 후속 연구가 필요할 것으로 생각된다.

• 대한약침학회지
• /
• 제17권4호
• /
• pp.61-65
• /
• 2014

Objectives: In this study, we investigated the oral toxicity of Gami-Jakyak Gamcho buja Decoction (Mecasin) to develop safe treatments. Methods: All experiments were conducted at the Medvill, an institution authorized to perform non-clinical studies, under the Good Laboratory Practice (GLP) regulations. In order to investigate the oral toxicity of Mecasin, we administered Mecasin orally to rats. Sprague-Dawley rats were divided into four groups of five male and five female animals per group: group 1 being the control group and groups 2, 3, and 4 being the experimental groups. Doses of Mecasin, 500 mg/kg, 1,000 mg/kg and 2,000 mg/kg, were administered to the experimental groups, and a dose of normal saline solution, 10 mL/kg, was administered to the control group. We examined the survival rate, weight, clinical signs, and gross findings. This study was conducted under the approval of the Institutional Animal Ethics Committee. Results: No deaths or abnormalities occurred in any of the four groups. Although slight decreases in the weights of some female rats were noted on the third day, no significant changes in weights or gross findings between the control group and the experimental groups were observed. To check for abnormalities in organs, we used microscopy to examine representative histological sections of each specified organ; the results showed no significant differences in any of the organs. Conclusion: The results showed that administration of 500 - 2,000 mg/kg of Mecasin did not cause any changes in weight or in the results of necropsy examinations. It also did not result in any mortalities. The above findings suggest that treatment with Mecasin is relatively safe. Further studies on this subject are needed to yield more concrete evidence.

• Toxicological Research
• /
• 제34권4호
• /
• pp.281-290
• /
• 2018

Exposure to chemical agents is an inevitable consequence of modern society; some of these agents are hazardous to human health. The effects of chemical carcinogens are of great concern in many countries, and international organizations, such as the World Health Organization, have established guidelines for the regulation of these chemicals. Carcinogens are currently categorized into two classes, genotoxic and non-genotoxic carcinogens, which are subject to different regulatory policies. Genotoxic carcinogens are chemicals that exert carcinogenicity via the induction of mutations. Owing to their DNA interaction properties, there is thought to be no safe exposure threshold or dose. Genotoxic carcinogens are regulated under the assumption that they pose a cancer risk for humans, even at very low doses. In contrast, non-genotoxic carcinogens, which induce cancer through mechanisms other than mutations, such as hormonal effects, cytotoxicity, cell proliferation, or epigenetic changes, are thought to have a safe exposure threshold or dose; thus, their use in society is permitted unless the exposure or intake level would exceed the threshold. Genotoxicity assays are an important method to distinguish the two classes of carcinogens. However, some carcinogens have negative results in in vitro bacterial mutation assays, but yield positive results in the in vivo transgenic rodent gene mutation assay. Non-DNA damage, such as spindle poison or topoisomerase inhibition, often leads to positive results in cytogenetic genotoxicity assays such as the chromosome aberration assay or the micronucleus assay. Therefore, mechanistic considerations of tumor induction, based on the results of the genotoxicity assays, are necessary to distinguish genotoxic and non-genotoxic carcinogens. In this review, the concept of threshold of toxicological concern is introduced and the potential risk from multiple exposures to low doses of genotoxic carcinogens is also discussed.

• 대한기계학회논문집A
• /
• 제35권10호
• /
• pp.1265-1271
• /
• 2011

본 논문에서는 유한요소 모델을 사용한 유체-구조 해석을 통하여 원자력 발전소 임시 받침대의 내진에 대한 안전성을 평가하였다. 임시받침대는 수중에 존재하기 때문에 유체-구조 연성을 통하여 유체의 영향을 고려하였다. 유체의 영향은 구조물의 단위길이당 추가질량으로 정의하여 적용하였다. 각각의 운전기준지진(OBE)과 안전정지지진(SSE)의 설계조건을 층응답스펙트럼(Floor Response Spectrum: FRS)으로 적용하여 진동해석과 내진해석을 수행하였다. 해석된 임시받침대의 최대변위는 운전기준지진에서 0.29mm 이고, 운전정지지진에서 최대변위는 0.36 mm 이다. 최대응력은 운전 기준지진에서 17.9 MPa, 안전정지지진에서 19.6 MPa 이며, 이 값은 재료의 항복강도의 23 %, 14 % 수준이다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제29권10호
• /
• pp.1470-1476
• /
• 2016

Octacosanol, which has prominent physiological activities and functions, has been recognized as a potential growth promoter in animals. A total of 392 1-d-old male Arbor Acres broiler chicks with similar body weight were randomly distributed into four dietary groups of seven replicates with 14 birds each supplemented with 0, 12, 24, or 36 mg octacosanol (extracted from rice bran, purity >92%)/kg feed. The feeding trial lasted for six weeks and was divided into the starter (day 1 to 21) and the grower (day 22 to 42) phases. The results showed that the feed conversion ratio (FCR) was significantly improved in broilers fed a diet containing 24 mg/kg octacosanol compared with those fed the control diet in the overall phase (day 1 to 42, p = 0.042). The average daily gain and FCR both showed linear effects in response to dietary supplementation of octacosanol during the overall phase (p = 0.031 and 0.018, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet showed a higher eviscerated yield, which increased by 5.88% and 4.26% respectively, than those fed the control diet (p = 0.030). The breast muscle yield of broilers fed with 24 mg/kg octacosanol diet increased significantly by 12.15% compared with those fed the control diet (p = 0.047). Eviscerated and breast muscle yield increased linearly with the increase in dietary octacosanol supplementation (p = 0.013 and 0.021, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet had a greater (p = 0.021) $pH_{45min}$ value in the breast muscle, which was maintained linearly in response to dietary octacosanol supplementation (p = 0.003). There was a significant decrease (p = 0.007) in drip loss value between the octacosanol-added and the control groups. The drip loss showed linear (p = 0.004) and quadratic (p = 0.041) responses with dietary supplementation of octacosanol. These studies indicate that octacosanol is a potentially effective and safe feed additive which may improve feed efficiency and meat quality, and increase eviscerated and breast muscle yield, in broiler chicks. Dietary supplementation of octacosanol at 24 mg/kg diet is regarded as the recommended dosage in the broilers' diet.

• Korean Chemical Engineering Research
• /
• 제51권3호
• /
• pp.319-324
• /
• 2013

합성가스를 생산하기 위한 메탄의 부분산화반응 특성을 $Ni/CeO_2-ZrO_2$, $Ni-Ru/CeO_2-ZrO_2$와 $Ni-Pd/CeO_2-ZrO_2$ 촉매체를 이용하여 조사하였다. 메탄의 부분 산화 개질 반응에서 촉매의 높은 활성과 안정성을 위하여 허니컴 구조의 금속모노리스 촉매 체를 적용하였다. 촉매분석은 XRD와 FE-SEM을 사용하였으며, 제조된 촉매들의 합성가스 제조 특성은 반응물 비(O/C), GHSV와 온도를 변화시키면서 연구하였다. 개질 실험에서 사용된 촉매 중에서 $Ni-Pd/CeO_2-ZrO_2$ 촉매 체가 가장 높은 활성을 보여 주었으며, $900^{\circ}C$, GHSV=10,000 $h^{-1}$과 O/C=0.55에서 99%의 메탄 전환율을 얻었다. O/C 비가 증가함에 따라 수소 yield는 증가되고, 반면에 CO yield는 거의 일정하게 유지됨을 확인할 수 있었다. 또한 GHSV가 증가할수록 메탄의 전환율은 감소하였으며, 높은 메탄의 전환율을 얻을 수 있는 GHSV의 범위는 10,000 $h^{-1}$ 이하임을 알 수 있었다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권4호
• /
• pp.625-634
• /
• 2003

Oil palm fronds (OPF) are one of the main by-products of the oil palm industry in Malaysia. It contains about 38.5 % crude fibre with ME values of about 5.65 MJ/kg dry matter. OPF has great potential to be utilized as a roughage source or as a component in a complete feed for ruminant animals. This paper briefly reviews the availability of OPF in Malaysia and its importance in the local beef and dairy industry. About 26 million metric tonnes of OPF are produced on dry matter basis annually during pruning and replanting operations in the plantations. The nutritive value of OPF and studies to improve its feeding value is highlighted. The optimum level of inclusion for ruminant feeding is 30 % and improvement to intake and digestibility can be further enhanced with addition of other oil-palm by-products. Performances of beef and dairy cattle fed fresh OPF or as silage, pellets and cubes are shown. Good quality OPF silage can be produced without using any additive and the significant improvement on the rate of growth and milk yield were shown. With good formulations, OPF based diets can allow live weight gains of between 600-850 g/day and for local crossbred dairy animals, milk yield of about 11.1 to 20.3 liter/day can be obtained. Pellet based on ground OPF seemed to be less well utilized for ruminant feeding due to its smaller particle size. OPF based cubes which have longer particle size is more suitable for beef and dairy cattle. Long-term feeding of OPF based feeds have been shown to produce good quality carcasses, and the meat is safe for consumption.