• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.153-158
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• 1995

보 및 평판의 진동에 대해서 에너지의 손실은 재료감쇠를 이용한 표면감쇠처리나 지지부에서의 감쇠처리에 의하여 증가될 수 있다. 감쇠재료를 이용한 표면감쇠처리의 예로서 보/평판 표면에 접착되는 감쇠 테이프나 코팅등은 아주 효과적임이 입증되었다. 마찬가지로 지지부 감쇠처리는 점탄성재료의 삽입에 의해서 설명될수 있다[1]. 보/평판의 감쇠에 대한 최근의 많은 연구들은 진동하고 있는 보/평판의 표면에 적용하는 감쇠 테이프 혹은 적층형태의 감쇠 처리방법에 대해서 주로 수행되었다. 일반적으로 표면감쇠처리방법은 진동감소에 아주 효과적이지만 실제 적용상에서 항상 가능한 것은 아니며, 이와 같은 경웨는 지지부 감쇠 처리방법에 의존하게 된다[2]. 감쇠특성을 갖는 점탄성재료를 실제로 적용할 때 보/평판의 유한한 길이가 점탄성재료로 지지되며 점탄성재료의 물성치와 치수에 따라서 계의 모우드 매개변수(고유진동수, 계의 손실계수 그리고 모우드형상)가 크게 달라진다. 그리고 이와 같은 계에 대해서는 지지부의 거동보다는 전체 시스템의 고유진동수와 손실계수 그리고 보 영역에서의 모우드 형상에 더 관심이 있으므로 지지부 영역을 집중매개변수(lumped parameter)로 나타내어 계를 해석할 수 있다. 일반적으로 보와 평판의 경계에서는 병진 및 회전방향의 강성 뿐만 아니라 두 강성사이에 연성효과도 동시에 발생하게 되므로 이 항을 고려하여 계를 모델링해야 한다. 본 연구에서는 우선 점탄성 재료에 의한 지지부영역의 등가 강성계수들을 구하고 경계에 강성행렬을 갖는 보의 등가시스템을 얻는다. 그리고 등가시스템의 주파수방정식으로부터 모우드 매개변수에 대한 지지부의 영향을 살펴본다. 또한 시스템이 비교적 복잡한 사각 평판의 진동에 대해서도 동강성행렬법(dynamic stiffness matrix method)을 이용하여 해석하고자 한다. 수준임이 입증되었다. 본 연구의 결과를 토대로우리나라 젊고 건강한 남성에게 적합한 무게상수는 작업자군에 대하여 25.05kg, 학생군에 대하여 20.24kg 으로 나타나 이는 미국 NIOSH 안전기준과 대체로 일치함을 발견하였다.ive structures utilized in Client/server architecture for distribution and cooperative processing of application between server and client this study presents two different data management methods under the Client/server environment; one is "Remote Data Management Method" which uses file server or database server and. the other is "Distributed Data Management Method" using distributed database management system. The result of this study leads to the conclusion that in the client/server environment although distributed application is assumed, the data could become centralized (in the case of file server or database server) or decentralized (in the case of distributed database system) and the data management method through a distributed database system where complete responsi

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.159-167
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• 2013

The aim of this study was to evaluate changes in demineralization resistance and bonding strength of light cured glass ionomer after the addition of nano hydroxyapatite in various ratios. Fuji II LC GIC (GC Co., Japan) was used as the control group and also as a base material for experimental group. HA was mixed into the RMGIC at various ratio to create a HA-LC GIC mixture, preparing six experimental groups, i.e. 5%, 10%, 15%, 20%, 25%, 30% HA-LC GIC. According to the results, the bonding strength increased due to the addition of HA, showing the maximum value at the 15% nano HA group (p < 0.05). Under CLSM observation after 4 days of demineralization, the HA groups were more resistant to demineralization compared to the control group. No significant difference was observed between HA groups. In analysis through SEM, the HA groups showed attachment of granular materials and decreased demineralized tooth surfaces under influence of HA particles.

• Journal of Aquaculture
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• v.15 no.3
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• pp.157-163
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• 2002

Thirteen groups, each consisting of 25 juveniles (0.64 g) of the Korean rockfish, Sebastes schlegeli were reared in aquaria after period of one week conditioning. Each group was fed with one of the 13 diets at the rate of 7~10% body weight (on a dry-matter basis) 2 times a day for 6 weeks. Each diet was supplemented with one of the following amino acids at 3g/kg diet: Alanine (Ala), Arginine (Arg), Glycine(Gly), Glutamate (Glu), Histidine (His), Isoleusine(Ile), Lysine (Lys), Methionine (Met), Phenylalanine (Phe), Proline (Pro), Threonine (Thr), Tryptophan (Trp) or Valine (Val). Groups fed with Pro, Thr, Met or Gly-supplemented diet showed significantly (p<0.05) higher weight gain and faster specific growth rate than the groups fed on other diets, while those fed Pro, Thr, Met or Gly were not significantly different each other(P>0.05). Feed efficiency (FE) of fish fed Pro was significantly higher than those fed the other diets except that fed Thr (P<0.05). However, there was no significant difference between FE of fish fed Pro and Thr, and among FE of fish fed Thr, Met and Gly (P>0.05). The requirement of rockfish is higher for Met and Thr. Extra Pro and/or Gly may also stimulate biosynthesis of the nucleic acids (IMP, GMP) which are known as the feed stimulant in fish.

• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.147-152
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• 2010

Poor fruit set during winter period is one of the biggest problem in plastic tunnel watermelon cultivation. Hand pollination is inevitable to maximize fruit set of the winter watermelon. Productivity and viability of pollen grain and organic solvents for pollen storage were investigated. All cultivars produced more than 10 mg/flower except for 'Kumchun' cultivar. Pollen amount per flower were 13.8 mg in 'Bok' and 12.1 mg in 'Speedkul'. Germination rate of pollen grains incubated at $30^{\circ}C$ right after soaking in pentane solvent were 76% in 'Kumchun' as the lowest and 92% in 'Apollokul' as the highest. The pollen of 'Bok' showed the highest germination rate by 75% after a 15-day storage in pentane. All cultivars showed their pollen germination rate below 25% after a 24-day storage. Among the cuitivars, speed of pollen tube growth in vitro were relatively lower in 'Kumchun' and 'Sambokkul' by below $50\;{\mu}m/hr$. Pollen tube of these cultivars tended to burst during its elongation on the medium. Pollen stored 24 hrs in organic solvents showed 45, 39, 34, 23, and 19% of germination in pentane, ethyl ether, n-hexane, ethyl acetate, and acetone, respectively. Compared with light condition, pollen viability was higher in darkness during pollen storage in organic solvents. Pollen grain was susceptible to the organic solvent. The viability of pollen grains seems to be influenced greatly by duration of soaking pollen in organic solvent and the polarity of solvents. Organic solvent damages surface of pollen grain and extent of damage was varied by the solvents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.5
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• pp.544-550
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• 1992

This study was investigated on the antitumor effects of protein-polysaccharide fraction(PPF) extracted from seaweeds such as sea-lettuce and gonpi toward sarcoma-180 cells. In the PPF extracted from these seaweeds, the polysaccharide contents of sea-lettrce and gonpi were 52.20% and 48.16%, respectively. The highest levels of constituents monosaccharides found in seaweeds was fructose. The major amino acids were aspartic acid, glutamic acid, glycine and cystein. The solid tumor growth inhibition showed the highest level of 64.55% when 50mg/kg sea-lettuce was administerated. The life prolongation effect was 18.31% at 50mg/kg of gonpi. In the effects of immunologic activity, when 50mg/kg sea-lettuce was administrated, the number of circulating leucocyte showed the highest level (65.11%). The number of total peritoneal exudate cells of the sea-lettuce administerated group was increased significantly in comparison with the control group. The hematological analysis of the experimental group was similar with that of the control group.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.358-369
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• 2000

Shielded metal arc welding machines with AC transformer have been widely used for thin-plate welding applications. Because of being bulky, heavy and of tap-changing property, so the SMAW's are changing to new power electronic circuits such as inverter circuit in order to reduce the system size and also to improve the welding performances at input output sides. The PWM inverter arc welding machine with diode rectifier has better output welding performances but it is has the plentiful harmonics and the lower input power factor. To solve these problems, input current-controlled scheme is considered for PWM inverter arc welding system, and then total input power factor is maintained to be more than 99%. Also a new combined control is proposed which can control both instantaeous welding output voltage and current under constant power condition, and as a result the variations of instantaneous current and voltage can be reduced to very narrow range in the V-I curve relationship, and hence the variance of welding current and voltage become so reduced. In addition the spatter generated during welding process is greatly reduced up to 70%. And the overall effiency can be improved up to 10%, which becomes higher when the load is lower.

• KSBB Journal
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• v.18 no.5
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• pp.412-417
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• 2003

We first investigated basic characteristics of reticulated polyurethane (PU) foams as microbial carriers. In general, the specific surface area of PU foams increases with respect to decreasing pore sizes. However, the number of microbes adhered on the unit surface of reticulated PU foams decreases with respect to decreasing pore sizes. Thus, as a result of totally considering all effects such as apparent density, hydrolysis rate, and adhesion, we can know that PU foams with 45 PPI is the most appropriate microbial carrier. In this study, we can also investigate the effect of various physico-chemical surface treatments on the adhesion of microbes on the surface of PU foams. We used a chitosan treatment, a PEI (Polyethylene Imine) treatment, a xanthane treatment and a plasma treatment. As a result of comparing all surface treatments, the plasma surface treatment was the best.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.151-157
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• 1987

Cyclobuxine D, a steroidal alkaloid, was extracted from Buxus microphylla var. koreana Nakai. The effects of cyclobuxine D on carrageenin-induced pleurisy and croton oil-induced granuloma pouch in rats was investigated and compared with those of aspirin, hydrocortisone ana dexamethasone. Intrapleural injection of 2% carrageenin caused the accumulation of exudate. The rate of plasma exudation, measured by the exuded dye amounts for 20 min in the pleural cavity after intravenous injection of pontamine sky blue, showed a peak at 5 hr. Cyclobuxine D (5, 20 and 50 mg/kg, i.p.) suppressed dose-dependently the accumulation of the pleural exudate and the exudation of dye. Among several methods used for screening and evaluation anti-inflammatory agents, granuloma pouch technic introduced by Hans Selye (Hans seyle, 1953) is considered as a simple and reliable method. An air pocket was produced in the subcutaneous tissue of the interscapular region by injection of 1 ml of 1% croton oil as irritant. Inflammatory exudate accumulated in the pouch during the succeding 14 days. Cyclobuxine D (5 and 20 mg/kg) decreased fluid volume in pouch and weight of pouch wall in granulomatous inflammation.

• Korean Journal of Poultry Science
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• v.34 no.1
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• pp.31-36
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• 2007

This experiment was conducted to determine the effect of betaine on immune response in laying hens. A total of 72 ISA-brown laying hens were divided into four groups of 18 hens each and fed corn-soybean meal based diets with addition of 0, 300, 600 and 1,200 ppm betaine for four weeks. The effect of betaine on splenocyte proliferations with mitogens, concanavalin A(Con A) and pokeweed mitogen(PWM), were assayed after incubation using [3H] thymidine uptake. Proliferations of splenocyte were significantly increased by activation of mitogen Con A or PWM. Mitogen effects of Con A were increased by Con A plus betaine injection(0.1 mM), whereas PWM effects did not affect in PWM plus betaine injection(0.1 mM) in vitro. Splenocyte of laying hens fed betaine tended to proliferate in the presence of PWM, but appeared to be slightly suppressed in the presence of Con A in vivo. Proliferation of splenocytes which were stimulated by Con A or Con A+betaine injection(0.1 mM) were increased in dietary 600 ppm betaine, but inhibited in dietary 1,200 ppm betaine supplementation. Spleen weights and sheep red blood cell(SRBC) titers of hens fed betaine tended to increase compared to those of control, but were not significantly different. These results suggested that betaine could increase splenocyte proliferation in vitro.

• Korean Journal of Organic Agriculture
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• v.22 no.2
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• pp.281-291
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• 2014

This study was conducted to examined the effect of dietary supplementation of yellow loess on the growth performance and blood component profiles in pigs. A total of one hundred fifty three pigs (60 one weeks old piglets and 93 adult pigs). Piglets were randomly divided into 3 groups which were control, control + 0.5% yellow loess, control + 1% yellow loess. We measured body weight and weight gain among treatment group. Indeed, we obtained hematological data with WBC, RBC, Hb, Hct, MCV, MCH, MCHC, RDW, and PLT in all loess supplemented group compared to the control. Adults were divided into 2 group (control and control + 1% yellow loess) and serum albumin levels in 1% yellow loess supplemented group was significantly higher than the control group (p<0.01). Amount of crude fat in feces was significantly reduced in yellow loess supplemented group (p<0.001), but no differences were observed at crude protein and crude ash in both groups. In carcass weight and back fat thickness, no significant differences were observed between control and yellow loess supplemented groups. The carcass grade was improved by the dietary supplementation of yellow loess compared to the pig fed control. As a results, dietary yellow loess improves nutrient absorption and carcass grade.