• Composites Research
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• 제33권3호
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• pp.115-124
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• 2020

적층복합재료, 특히 탄소섬유 복합재료는 금속에 비해 가벼우며 상대적으로 비강도 및 비강성이 뛰어나기 때문에 항공 우주 산업 및 자동차 산업 등과같이 광범위한 분야에서 사용되고 있다. 그러나, 적층 복합재료는 섬유의 배열이 모두 면내방향으로 배열되어있기 때문에 박리가 발생한다는 큰 단점이 있으며, 이는 적층복합재료의 응용분야를 제한한다. 본 연구에서는 먼저 π-빔과 평판이 결합된 형태의 적층복합재료 T-빔을 개발하고, 구조해석 및 기계적 물성평가를 통하여 설계변수를 최적화하였다. 이후 적층복합재료 T-빔의 설계변수를 3D 직조 프리폼에 동일하게 적용하여 T-빔을 개발하였으며, 적층구조에 비하여 향상된 기계적 강도를 달성할 수 있었다. 이러한 연구결과는 강도향상을 필요로 하는 기존의 적층복합재료 구조물에 적용 가능할 것으로 기대된다.

• Journal of applied mathematics & informatics
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• 제34권3_4호
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• pp.269-284
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• 2016

In this paper, we firstly use Krasnosel'skii fixed point theorem to investigate positive solutions for the following three-point boundary value problems for p-Laplacian with a parameter $({\phi}_P(D^{\alpha}_{0}+u(t)))^{\prime}+{\lambda}f(t, u(t))=0$, 0$D^{\alpha}_{0}+u(0)=u(0)=u{\prime}{\prime}(0)=0$, $u^{\prime}(1)={\gamma}u^{\prime}(\eta)$ where ϕ_p(s) = |s|^p−2s, p > 1, $D^{\alpha}_{0^+}$ is the Caputo's derivative, α ∈ (2, 3], η, γ ∈ (0, 1), λ > 0 is a parameter. Then we use Leggett-Williams fixed point theorem to study the existence of three positive solutions for the fractional boundary value problem $({\phi}_P(D^{\alpha}_{0}+u(t)))^{\prime}+f(t, u(t))=0$, 0$D^{\alpha}_{0}+u(0)=u(0)=u{\prime}{\prime}(0)=0$, $u^{\prime}(1)={\gamma}u^{\prime}(\eta)$ where ϕ_p(s) = |s|^p−2s, p > 1, $D^{\alpha}_{0^+}$ is the Caputo's derivative, α ∈ (2, 3], η, γ ∈ (0, 1).

• Kyungpook Mathematical Journal
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• 제61권3호
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• pp.487-494
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• 2021

In this paper, we study rings with Noetherian spectrum, rings with locally Noetherian spectrum and rings with t-locally Noetherian spectrum in terms of the polynomial ring, the Serre's conjecture ring, the Nagata ring and the t-Nagata ring. In fact, we show that a commutative ring R with identity has Noetherian spectrum if and only if the Serre's conjecture ring R[X]_U has Noetherian spectrum, if and only if the Nagata ring R[X]_N has Noetherian spectrum. We also prove that an integral domain D has locally Noetherian spectrum if and only if the Nagata ring D[X]_N has locally Noetherian spectrum. Finally, we show that an integral domain D has t-locally Noetherian spectrum if and only if the polynomial ring D[X] has t-locally Noetherian spectrum, if and only if the t-Nagata ring $D[X]_{N_v}$ has (t-)locally Noetherian spectrum.

• 한국해안해양공학회지
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• 제6권1호
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• pp.12-22
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• 1994

외력에 의해 생성된 일정 수심 위를 전파하는 파랑변위의 시간변화를 점근 근사법을 사용하여 분석하였다. Stationary Phase 방법, Steepest Descents 방법 그리고 선두파랑 근사법을 사용하였다. 1차원 파랑과 2차원 파랑의 해면변위에 대한 근사법을 검증하기 위해 근사식과 수치적분으로 계산한 변위를 도시하였다. 파고 감소율에 대한 기존의 결과인 1차원 선두파랑의 감소율은 t$^{-1}$3/, 후속파랑은 t$^{-1}$2 그리고 2차원 후속파낭은 t$^{-1}$로 이들 근사식의 타당함을 입증하였다. 그러나 2차원 선두파랑의 감소율은 기존 Kajiura의 결과인 t$^{-4}$ 3/과 다른 t$^{-5}$6/이 적합함을 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권6호
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• pp.784-793
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• 2004

Major objective was to evaluate three doses of bST (POSILAC(R)) injected into Holstein cows during the transition period and through 56 d of lactation for potential to improve DMI, BCS, BW, metabolites, hormones, IGF-I and milk production. Biweekly injections of bST (0, 5.1, 10.2, or 15.3 mg bST/d) began 28 d before expected parturition and continued through 56 d postpartum. Twenty-three of the 25 multiparous Holstein cows assigned randomly to four groups completed experiment (7, 5, 6 and 5 cows/group, respectively). The DMI, BW and BCS were recorded weekly throughout the prepartum and postpartum periods and blood samples were collected thrice weekly for analyses of ST, insulin, $T_{4}$, $T_{3}$, IGF-I, glucose and NEFA. Milk yields were recorded daily through 60 d postpartum and milk components measured once weekly. Mathematical model for data analyses for prepartum and postpartum periods included treatment, calving month, and the two-factor interaction. Cows injected with 10.2 and 15.3 mg bST prepartum had greater mean prepartum concentrations of ST and IGF-I. Prepartum injections of bST did not affect prepartum BW or BCS. On average, cows injected postpartum better maintained their BCS during first 60 d of lactation (3.15$\pm$0.06, 3.12$\pm$0.007, 3.20$\pm$0.006 and 3.58$\pm$0.009). Treatments did not affect mean prepartum DMI but cows injected with 15.3 mg bST/d had greatest DMI and greatest mean daily MY during the first 3 wk and tended to be greater during first 60 d of lactation. Cows injected with two highest bST doses (10.1 and 15.2 mg/d) had greater mean postpartum concentrations of ST and $T_{3}$, but IGF-I, $T_{4}$, glucose and NEFA did not differ across groups. No adverse effects of bST treatment were observed.

• 한국축산식품학회지
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• 제32권4호
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• pp.512-519
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• 2012

본 시험은 육계에게 맥섬석 또는 한방제재를 첨가하여 육계의 생산성과 육질에 미치는 효과를 알아보기 위하여 브로일러 600수를 공시하여 4처리구당 50수씩${\times}$3반복으로 나누어, 대조구(0%), T1구(맥섬석 0.3%), T2구(한방소재0.3%), T3구(맥섬석0.3%+한방소재0.3%)를 5주 동안 첨가 급여한 결과는 다음과 같다. 총 증체량과 일당증체량은 다른 처리구에 비하여 T2구가 가장 높았고(p<0.05), 폐사율은 대조구(8%)가 처리구보다 크게 높아 통계적인 유의차가 나타났다(p<0.05). 혈중 콜레스테롤은 대조구(111.8 mg/dL)가 처리구(102.5-107.7 mg/dL)보다 더 높았으나, 혈중 IgG는 처리구(5.23-6.71 mg/dL)가 대조구(4.5 mg/dL)보다 더 높게 나타났다(p<0.05). 계육의 가열감량과 전단력은 처리구(각각 15.25-16.55%, 1.47-1.55 $kg/cm^2$)가 대조구(17.08%, 1.91 $kg/cm^2$)보다 더 낮았으나, 보수성은 오히려 처리구(55.97-56.01%)가 대조구(54.40%)보다 더 높았다(p<0.05). 가슴육의 콜레스테롤 함량은 대조구에 비하여 처리구(80.81-83.59 mg/100 g)가 더 낮아 통계적인 유의차가 나타났다(p<0.05), 결론적으로 육계에게 맥섬석과 한방제재 참가급여는 계육의 콜레스테롤 함량을 저하시키는 개선의 효과가 있었다.

• Journal of Periodontal and Implant Science
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• 제30권1호
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• pp.39-52
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• 2000

Polypeptide growth factor belong to a class of potent biologic mediator which regulate cell differentiation, proliferation, migration and metabolism. 1,25-dihydroxyvitamin $D_3$ decrease cell proliferation, and stimulate alkaline phosphatase activity which express in osteoblast during cell differentiation period. IGF-I is known to stimulate cell proliferation and differentiation too. 1,25-dihydroxyvitamin $D_3$ is known to increase IGF-I binding sites and IGF binding protein which inhibite the effect of IGF. The purpose of this study is to evaluate potential role of IGF-I as mediator that control the action of 1,25-dihydroxyvitamin $D_3$. MC3T3-E1 cell were seeded $5{\times}10^5/ml$ at 100mm culture plate in ${\alpha}-MEM$ containing 10% fetal bovine serum. After 48 hour incubation period, medium were changed ${\alpha}-MEM$ containing 5% fetal bovine serum. After 24 hours, $10^{-9}M$ 1,25-dihydroxyvitamin $D_3$ added. Total mRNA was extracted at 0, 6, 24, 48, 72 hour. PRPCR method was programed for the detection of IGF-I mRNA. In the both groups of 1,25-dihydroxy vitamin $D_3$ treated and control, alternative splicing form of IGF-I, IGF-IA and IGF-IB were expressed. In the 1,25-dihydroxyvitamin $D_3$ treated group, IGF-I mRNA expression was matained until 24 hour, there after expression was decresed. MC3T3-E1 cell were seeded $2.5{\times}10^4/ml$ at 24well plate in ${\alpha}-MEM$ containing 10% fetal bovine serum. After 48 hour incubation period, medium were changed ${\alpha}-MEM$ containing 3% fetal bovine serum. After 24 hours, $10^{-9}M$ 1,25-dihydroxyvitamin $D_3$ and 10 ng/ml IGF-I were added separately or together. Cell were cultured for 1 and 3 days, $2{\mu}Ci/ml\;[^3H]$ -thymidine was added for the last 24h of culture of each days. ${[^3H]}$-thymidine incorporation in to DNA was measured and expressed counter per minute(CPM). DNA synthetic activity was significantly decreased by 1,25-dihydroxyvitamin $D_3$ both at 1 day and 3 day, and in the combination group of 1,25-dihydroxyvitamin $D_3$ and IGF-I, DNA synthetic activity was also decreased both at 1 day and 3 days. IGF-I did not affect the DNA synthetic activity compared to control group both at 1 day and 3 day. From the above results, 1,25-dihydroxyvitamin $D_3$ was potent inhibitor of cell proliferaton in MC3T3-E1 cells. It assumed that the effect of 1,25-dihydroxyvitamin $D_3$ on osteoblast proliferation may be mediated in part by decreased level of IGF-I.

• 수산해양기술연구
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• 제41권2호
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• pp.122-128
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• 2005

The experiments were conducted to fine out the handling characteristics of the FMT(Frame Mideater Trawl) in the southern waters of Korea using a trawler "DONGBAEK" belongs to Yosu National University. The realtionship between the net depth D(m) and the warp length L(m) at the towing speeds of 2.5k't and 3.5k't werw as follows ; D(m) = 0.30L - 1.3(2.5k't), D(m) = 0.16L - 1.5(3.5k't). Therefore, the net depth was 3.0m deeper when the warp length was 10m longer at the towing speed of 2.5k't and was 1.6m deeper for 10m longer at the speed of 3.5k't, respectively. The sinking speed of FMT was 6.5m/min when the warp releasing speed was 24m/min at the towing speed of 2.5k't and was 3.8m/min for 25m/min at the towing speed of 3.5k't, respectively. The rising speed of FMT was 6.9m/min when the warp rewinding speed was 28m/min at the towing speed of 2.5k't and was 5.3m/min for 25m/min at the towing speed of 3.5k't, respectively. The mean elapsed time getting to the stable towing condition was 104sec at the towing speed of 2.5k't and was 105sec at the towing speed of 3.5k't, respectively, and there was no time difference for the towing speed variation. During the towing, the net depth was comparatively stable on the condition of no change for the warp length and the towing speed.

• 소성∙가공
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• 제10권1호
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• pp.23-29
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• 2001

In this study, the optimized initial hole shape for T-branch forming was proposed to obtain effective welding region. Design variables were determined by approximation analysis using volume constant condition. We performed 3D elastic-plastic FEM(Finite Element Method) analysis to simulate T-branch forming process. The variation of height and thickness of T-branch with various hole shapes was investigated. The optimized initial hole shape equation was obtained by using results for the numerical analysis.

• 생명과학회지
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• 제24권7호
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• pp.777-783
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• 2014

항암제로 알려진 cisplatin과 t-BHP를 토끼에 투여하여 유도된 급성 신부전 시 산조인 추출액을 처리하였을 때 신장 세포의 보호에 미치는 항산화 효과를 조사하였다. 신장을 분리한 후 신피질 절편 실험에서 세포의 손상을 유발하는 지질과산화 및 LDH 실험에서 t-BHP 단독 처리 시 대조군에 비하여 각각 3배, 5배 이상 증가하였으나 산조인 추출액 0.5%를 동시 처리하였을 때는 대조군 수준으로 감소하였다. Creatinine 측정과 지질과산화 실험에서 cisplatin $5mg{\cdot}kg^{-1}$을 복강 투여한 군의 creatinine 농도가 $2.13{\pm}0.1mg{\cdot}dl^{-1}$로 나타났으나 산조인 추출액 $50mg{\cdot}kg^{-1}{\cdot}day^{-1}$을 7일간 전처리 후 cisplatin 투여 48시간 경과한 군은 $0.84{\pm}0.1mg{\cdot}dl^{-1}$로 creatinine의 농도가 약 60% 감소되는 신장보호 효과를 나타내었고, 지질과산화 검사는 cisplatin 단독 투여 시 대조군에 비하여 1.6배 높게 나타났으나 산조인 추출액 전처리 시 1.1배로 대조군과 유사하였다. 병리조직 검사는 cisplatin 단독 처리군에서 근위곱슬세관이 대조군에 대하여 더 붉게 염색되었으며 근위곱슬세관은 내강의 융모세포가 탈락하여 공포를 형성하였다. 그러나 산조인 추출액을 7일간 전처리한 군에서는 근위곱슬세관이 대조군과 유사한 염색소견을 보였고 근위곱습세관도 내강의 융모세포 탈락이 거의 나타나지 않았다. 따라서 cisplatin과 t-BHP에 의해 유발된 신장세포 손상에 대하여 산조인 추출액이 항산화 효과를 보였다.