• Fisheries and Aquatic Sciences
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• 제7권1호
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• pp.39-45
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• 2004

Six demographic parameters including life span (LS), maturation time (MT), net reproduction rate (Ro), mean generation length (G), innate capacity for increase $(r_m)$ and finite rate of increase $(\gamma)$ were estimated in the rotifer (Brachionus rotundiformis) cultured at three salinities of 5, 20 and 34 PSU and under a constant temperature of $28^{\circ}C$. The maximum life spans at salinities of 5, 20 and 34 PSU were 17, 12 and 13 days, respectively. The shortest maturation time (24 hr) was recorded at 5 PSU, and the rotifer at 20 PSU showed a most delayed maturation (192 hr). The maximum reproduction rate was 42 offspring per female in rotifer cultured at 5 PSU, while the longest generation length (8 days) was observed at 20 PSU. Maximum and minimum values of $r_m$ (1.56 and 0.46 individual per day) and $(\gamma)$ (6.67 and 1.70 individuals per day) were calculated at 5 and 34 PSU, respectively. Salinity also showed strong effect on correlation of the demographic traits examined. ANOVA revealed significant differences (P<0.05) between demographic parameters of the rotifer at the three salinity condition. Considering the higher values of life span, innate capacity and finite rate of increase, and shortest maturation time at 5 PSU, the rotifer we examined had a higher reproductive potential and longer life span at 5 PSU rather than at 20 or 34 PSU.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.169-175
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• 1993

Possibility of fatigue failure in punching shear of reinforced concrete decks of highway bridges is analytically investigated by applying Matsui et al.'s experimental finding to models of 2-meter span decks designed in compliance with previous and current codes. Decks made of concrete of compressive strength of 240㎏/㎠ showed longer fatigue life than decks made of 210㎏/㎠ concrete at the same Md/U rations ; higher Md/U ratio resulted in linger fatigue life but its effect is insignificant in decks having effective depths of 14 and 15cm. Decks designed to higher load factors as specified by current codes showed longer fatigue life than decks designed to lower load factors specified by previous codes ; yet fatigue failure appeared to occur in both decks within their normal life span, thus indicating need for redefining the minimum deck thickness.

• 약학회지
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• 제38권6호
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• pp.795-799
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• 1994

Some components and antitumor effect of antler and fermented antler with Bacillus P-92 were determined. By fermenting the antler with Bacillus P-92, the amount of free amino acids, polypeptides and other compounds were increased. The free amino acid of the fermented antler was 6-fold higher than those of the untreated antler. Sarcoma 180 cells were intraperitoneally implanted into ICR mice to determine the effect of fermented antler and untreated antler on life span prolongation. The life span of ICR mouse treated with antler and fermented antler were prolonged to 24.4% and 39.2%(p<0.05), and survival rates were 22% and 33%, respectively. In addition, the induction of neutrophil was 2.3-fold and 3.4-fold, respectively.

• Steel and Composite Structures
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• 제23권4호
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• pp.435-444
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• 2017

In the past, the progressive collapse resulting from local failures during accidents has caused many tragedies and loss of life. Although long-span spatial grid structures are characterised by a high degree of static indeterminacy, the sudden failure of key members may lead to a catastrophic progressive collapse. For this reason, it is especially necessary to research the progressive collapse resistance capacity of long-span spatial grid structures. This paper presents an evaluation method of important members and a novel dynamic analysis method for simulating the progressive collapse of long-span spatial grid structures. Engineering cases were analysed to validate these proposed method. These proposed methods were eventually implemented in the progressive collapse analysis of the main stadium for the Universiade Sports Center. The roof of the structure was concluded to have good resistance against progressive collapse. The novel methods provide results close to practice and are especially suitable for the progressive collapse analysis of long-span spatial grid structures.

• Asian-Australasian Journal of Animal Sciences
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• 제26권11호
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• pp.1511-1517
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• 2013

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of life span. Regression of Life Span on Lifetime profit indicated that there was an increase of 3,800 Won (approximately $3.45) of lifetime profit per day increase in life span. This is evidence that care of each cow is necessary to improve net return and important for farms maintaining profitable cows. The estimates of heritability of age at first calving, first two calving intervals, days in milk for lifetime, lifespan, milk income and lifetime profit were 0.111, 0.088, 0.142, 0.140, 0.143, 0.123, and 0.102, respectively. The low heritabilities indicated that the productive life and economical traits include reproductive and productive characteristics. Age at first calving and interval between first and second calving had negative genetic correlation with lifetime profit (-0.080 and -0.265, respectively). Reducing age at first calving and first calving interval had a positive effect on lifetime profit. Lifetime profit increased to approximately 2,600,000 (2,363.6) from 800,000 Won ($727.3) when age at first calving decreased to (22.3 month) from (32.8 month). Results suggested that reproductive traits such as age at first calving and calving interval might affect various economical traits and consequently influenced productive life and profitability of cows. In conclusion, regard of the age at first calving must be taken with the optimum age at first calving for maximum lifetime profit being 22.5 to 23.5 months. Moreover, considering the negative genetic correlation of first calving interval with lifetime profit, it should be reduced against the present trend of increase.

• Structural Engineering and Mechanics
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• 제78권1호
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• pp.87-102
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• 2021

Long span cross-rope suspension structure is an innovative structural system evolved from typical Cross-Rope Suspension (CRS) guyed tower, a type of supporting system with short span suspension cable supporting overhead power transmission lines. In mountainous areas, the span length of suspension cable was designed to be extended to hundreds or over one thousand meters, which is applicable for crossing deep valleys. Vortex Induced Vibration (VIV) of overhead power transmission lines was considered to be one of the major factors of its fatigue and service life. In this paper, VIV and its controlling by Stockbridge damper for long span CRS was discussed. Firstly, energy balance method and finite element method for assessing VIV of CRS were presented. An approach of establishing FE model of long span CRS structure with dampers was introduced. The effect of Stockbridge damper for overall vibration of CRS was compared in both theoretical and numerical approaches. Results indicated that vibration characteristics of conductor in long span CRS compared with traditional tower-line system. Secondly, analysis on long span CRS including Stockbridge damper showed additional dampers installed were essential for controlling maximum dynamic bending stresses of conductors at both ends. Moreover, factors, including configuration and mass of Stockbridge damper, span length of suspension cable and conductor and number of spans of conductor, were assessed for further discussion on VIV controlling of long span CRS.

• 대한한방내과학회지
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• 제28권2호
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• pp.321-332
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• 2007

Objectives : Anticancer and immune-modulating effects of several Korean medical prescriptions including Yukgunja-tang, Bohwa-tang, Sogam-Won, and Kamiboa-tang were investigated. Methods : In vitro anti-cancer effects were measured by cytotoxicity MTT assay using SNU-1 gastric cancer cell lines, In vivo anti-cancer effects were measured by increased life span of S-180 sarcoma-injected ICR mouse. Immune-modulating effects were analyzed by measuring hemagglutinin titer, appearance of rosette forming cells, lymphocyte proliferation, and phagocytic index in methotrexate-pretreated mice. Results : In vitro assay showed that only Sogam-won showed cytotoxic effect with $IC_{50}$ of 87.9 ${\mu}g/ml$. All other prescriptions showed no cytotoxic effects against SNU-1 gastric cancer cell line. However, in vivo assay showed that Sogam-won showed lowest anti-cancer effects in contrast to its highest cytotoxic effects, Kamiboa-tang, which showed no cytotoxic effect, showed the highest in vivo anticancer effects, with increased life span of 140%. Kamiboa-tang showed significant immune-enhancing activities by significantly increasing rosette forming cells, lymphocyte proliferation, and phagocytic index in methotrexate-pretreated mice (P<0.05). Conclusion : The anticancer effect of Kamiboa-tang is not mediated by direct inhibition of cancer cells but is mediated by improving immune reactions against cancer cells.

• 한국가족복지학
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• 제23호
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• pp.43-70
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• 2008

본 연구는 지적 장애인을 돌보는 어머니의 사회적 지지가 돌봄 자기효능감에 주는 영향을 분석하였으며, 이 영향이 장애인 자녀가 속한 생애주기에 따라 달라지는가를 탐색하였다. 530명의 사례에 대한 분석 결과, 전체집단에서 어머니가 지각한 사회적 지지가 많을수록 돌봄 자기효능감이 높은 것으로 나타났다. 그런데 자녀 생애주기의 조절효과를 살펴본 결과, 아동의 어머니 집단에 비교해 청소년의 어머니 집단과 성인의 어머니 집단에서 효과의 크기가 통계적으로 유의하게 달랐다. 각 집단에 대한 분석 결과, 아동의 어머니 집단에서는 사회적 지지가 돌봄 자기효능감에 영향을 주지 않은 반면, 청소년의 어머니 집단과 성인의 어머니 집단에서는 사회적 지지가 돌봄 자기효능감에 영향을 주는 것으로 나타났다. 본 연구를 통해 장애인 가족 연구에서 생애발달적 관점이 지지되었으며, 실천적으로는 청소년기와 성인기의 자녀를 둔 장애인 가족에 대한 사회적 지지의 중요성이 더욱 강조되어야 할 것으로 생각되었다.

• 대한가정학회지
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• 제19권2호
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• pp.1-9
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• 1981

The phenomena of memory have been shown to come out early in life and to develop drastically for early childhood. Therefore, the purpose of this study were examine the development of memory of Korean children and also to see the memory span of Korean children. the subjects in this study were 80 children (male and female each 40 children) from age 3 to age 6. These subjects were devide into two age groups (3~4 age, 5~6 age). the stimulus materials were the numbers and the words. The numbers in this study were chosen from the number problems of WISC. The 42 words which consisted of two phonemes were selected. The number of items was 3 to 9 on the first through the last trial. altogether 14 trials, 7 trials for numbers and 7 trials for words, were given to each subject. Free recall method was sued. The following conclusions could be made. 1. The memory span of Korean early childhood increased as the age of the children increased. 2. The primacy effect was appeared when the age increased. Therefore, rehearsal was appeared as the age of the Korean early childhood increased.

• Nutrition Research and Practice
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• 제1권2호
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• pp.105-112
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• 2007

Ascorbic acid has been reported to extend replicative life span of human embryonic fibroblast (HEF). Since the detailed molecular mechanism of this phenomenon has not been investigated, we attempted to elucidate. Continuous treatment of HEF cells with ascorbic acid at ($200{\mu}M$) from 40 population doubling (PD) increased maximum PD numbers by 18% and lowered $SA-{\beta}-gal$ positive staining, an aging marker, by 2.3 folds, indicating that ascorbic acid extends replicative life span of HEF cells. Ascorbic acid treatment lowered DCFH by about 7 folds and Rho123 by about 70%, suggesting that ascorbic acid dramatically decreased ROS formation. Ascorbic acid also increased aconitase activity, a marker of mitochondrial aging, by 41%, indicating that ascorbic acid treatment restores age-related decline of mitochondrial function. Cell cycle analysis by flow cytometry revealed that ascorbic acid treatment decreased G1 population up to 12%. Further western blot analysis showed that ascorbic acid treatment decreased levels of p53, phospho-p53 at ser 15, and p21, indicating that ascorbic acid relieved senescence-related G1 arrest. Analysis of AP (apurinic/apyrimidinic) sites showed that ascorbic acid treatment decreased AP site formation by 35%. We also tested the effect of hydrogen peroxide treatment, as an additional oxidative stress. Continuous treatment of $20{\mu}M$ of hydrogen peroxide from PD 40 of HEF cells resulted in premature senescence due to increased ROS level, and increased AP sites. Taken together, the results suggest that ascorbic acid extends replicative life span of HEF cells by reducing mitochondrial and DNA damages through lowering cellular ROS.