• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.429-437
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• 2010

The aim of this study was to evaluate the fluoride release and microhardness of Beautifil II as giomer(Group I), F2000 Compomer as compomer(Group II), GC Fuji II LC Capsule as resin-modified glass ionomer(Group III) and $Filtek^{TM}$ Z350 as composite resin(Group IV) according to time. Forty discs(5 mm diameter and 2 mm height) were prepared for each material. Each disc was immersed in 3 ml of de-ionized water within polyethylene tube and stored at $37^{\circ}C$. Evaluations were performed by pH/ISE meter for analysis of fluoride release and hardness testing machine for analysis of microhardness over 31 days. The results can be summarized as follows : 1. For all groups except group IV, the greatest fluoride release was observed after the first day of the study period and then dramatically diminished over time. On the 7th day of the study period, fluoride release level was stabilized. 2. Group III showed the highest fluoride release among test groups and then group II, group I were followed. Significant difference in cumulative fluoride release over 31 days was found between each groups. Group IV showed no fluoride release during study period. 3. Group IV showed the highest microhardness among test groups and then group I, group II, group III were followed. Significant difference in microhardness was found between each group, except between group I and group II. 4. After 31 days, microhardness was slightly diminished in every group. However, no significant difference was found.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.6
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• pp.857-864
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• 2009

This experiment was conducted to investigate the effects of interaction between $1{\alpha}$-hydroxycholecalciferol ($1{\alpha}$-OH $D_3$) and phytase on growth performance, parameters of tibia and plasma, and meat quality of 1- to 21-d-old broilers. Two hundred and forty male, 1-d-old Arbor Acres broilers were randomly assigned to 20 cages, with 12 chicks per cage. Five treatments were designed, with four cages each. A 2${\times}$2 factorial experiment was designed to test 0 and 5 ${\mu}g/kg$ of $1{\alpha}$-OH $D_3$ in combination with 0 and 500 U/kg of phytase. A basal diet was formulated to contain 2.9 g/kg of non-phytate phosphorus (NPP), and the control diet was formulated to contain a normal level of NPP (4.5 g/kg). Results showed that $1{\alpha}$-OH $D_3$ alone increased tibia ash, contents of calcium and phosphate, breaking strength, concentrations of plasma calcium and phosphate, and water-holding capacity of breast and thigh meat, while it decreased growth of broilers. Phytase alone improved performance and tibia quality. Although growth of broilers was lower than that of the positive control when the diet was supplemented with $1{\alpha}$-OH $D_3$ and phytase, tibia quality was significantly improved by the addition of $1{\alpha}$-OH $D_3$ and phytase. These data suggest that interaction between $1{\alpha}$-OH $D_3$ and phytase at 2.9 g/kg of dietary NPP could significantly increase bone quality of 1- to 21-d-old broilers, while not improving growth performance.

• Korean Journal of Plant Tissue Culture
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• v.25 no.1
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• pp.13-19
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• 1998

We have reported previously that intact embryogenic cells can be used instead of protoplasts for electroporation-mediated transformation of zoysiagrass and rice. In this study, conditions of the tissue electroporation were examined to optimize the procedures. Embryogenic cell suspensions were established in liquid MS medium containing 2 mg/L of 2,4-D with embryogenic calluses induced from mature embryos of Z. japonica. The suspension-cultured cell clumps were electroporated with 35S-gusA expression vector DNA, and degrees of DNA introduction into the cells were determined by histological expression rates of the gusA marker gene. DNA transfer into the cell clumps occurred in wide range of voltage (100-400 V) and capacitance (10-1980 $\mu\textrm{F}$), but more in the ranges of 200-300 V and 330-800 $\mu\textrm{F}$ DNA concentrations higher than 6 $\mu\textrm{g}$/mL were adequate for GUS expression of the electroporated cells. DNA transfers were confirmed in all three embryogenic cell lines but only in one out of eleven non-embryogenic lines. Positive GUS expressions occurred with DNAs added even 20-40 h after pulse treatments. As a promoter of gusA, Act1 and Ubi1 were effective 7 and 5 times than 35S respectively in number of GUS expression units on electroporated cell clumps. Embryogenic cell clumps survived and regenerated into plantlets after pulse treatments of wide range of conditions.

• Journal of Preventive Medicine and Public Health
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• v.27 no.4 s.48
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• pp.763-776
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• 1994

Recent studies reveal that grip forces during the hand-arm vibration are most significant for the genesis of vibration-induced white linger syndrome. Therefore, exerted grip forces and skin temperatures of fingers were regarded as dependent variables in experiments and the effects of grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force were studied. The objectives of the present study were, first, to varify and compare the changes of grip force affected by grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force and, second, to observe the reaction of finger skin temperature affected by above factors. Forty-six healthy male students ($25.07{\pm}2.85$) participated in five systematically permuted trials, which endured 4 minutes each other. Experiments were executed in a special chamber with an air temperature of 21C. In each experiments, the subjects were exposed to five experiment types: (1) grip force of 25N only, (2) pushing force of 50N, (3) acceleration of vibration $7.1m/sec^2(z-direction)$, (4) pink noise of 95 dB (A) and (5) combination of pushing force 50N and acceleration of vibration $7.1m/sec^2$. A repeated-measures analysis of variance (ANOVA) was performed on the grip force to test whether it was affected by noise, pushing force, vibration and pushing force. The present results show that vibration was significantly related to the increase of grip force, but the other factors, such as pushing force, noise and grip temperature had no signigicant influence on the increase of grip force, and that the reaction of finger skin temperature were significantly affected by the skin temperature at start of experiment and grip temperature, not grip force and other experimental conditions. Therefore, we suggest that the management for decreasing the grip force is meaningful to prevent the occurrence of Hand-arm vibration syndrome (HAVS).

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.47-62
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• 2000

This study investigated the effect of soil animals at forest fire area, and it carried out the mountain located at Jundae Ri, Houeng-chen Myen, Ha-dong Gun, Kyoung-Nam Province, southern part of Korea, where burned out about 50 hectars on April 11, 1997. Vegetation of the examined area absolutely dominated with the pines of 7-14 cm in diameter and 20 to 30 years old and the rest were covered with mixed forest with a shrub such as the oak (Quereus mongolia Fisch, Quereus variabilis BI, Quereus dentana Thunb), snowbell(Styrax japonica, S, et, z), lacquer tree (Rhus trichocarpa Mig), azalea (Rhododendron mucronulatum Turcz), etc. And there were simple area organized as a herbaceous plant, and the burnt area was poor experimental sites, where litter layer and herbaceous plant disappeard due to fire, and the unburnt area was rich in surface plant, dead leaves, twigs, etc. But the ground cover vegetations were poor in the unburnt area. The distribution of each animal groups, the seasonal fluctuation in population density, the biomass of meso$.$macroarthropods and the relationship between soil animal and some environmental factors were investigated and analyzed at each experimental area. The result are summarized as follow: 1. Identificated 257,087 individuals of soil microarthropods were classified into 7 classes and 24 orders of Arachinida, Insecta, Chilopoda, Symphyla, Diplopoda, Isopoda and Oligochaeta., and identified 8,006 individuals of the total meso$.$macroarthropods were classified into 7 classes and 20 orders of Arachinida, Insecta, Chilopoda, Symphyla, Diplopoda, Isopoda and Oligochaeta. 2. Among the total soil microarthropods, Arachinida formed 70.9%, followed by Insecta for 28.4% and among the total meso$.$macroarthropod , Insecta formed 57.6%, followed by Chilopoda for 23.8%.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.564-571
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated fish fauna, community and physical habitat conditions in the Dal Stream of Han River Basin. Field monitoring including fish sampling was conducted from September 2008 to October 2009. A total number of fish caught in the 5 sites was 2,080 representing 9 families 35 species, and 19 species (54.3%) including Acheilognathus koreensis and Iksookimia koreensis were Korean endemic species during the study period. The most frequently found species in number was pale chub (Zacco platypus, 25.7%, n = 632) followed by Coreoleuciscus splendidus (18.0%, n = 375) and Z. koreanus (13.0%, n = 272). The lower reach of Dal Stream was more abundance of species, high diversity, evenness and richness, and lower dominance index than those of the upper reach. According to the dendrogram established at 0.63 level of similarity rate, sampling stations were divided into 2 groups. Most of upper streams in Korea consist of riffles and runs that are repeatedly followed by another one. However, stream channelization and leveling have caused reduction of habitat diversity. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.101-101
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• 2011

현재 국내에서 시행되고 있는 '4대강 살리기 사업'은 하천에서 발생하는 홍수 및 가뭄재해방지를 위한 다양한 공학적 노력을 시도하고 있다. 특히 안정적인 수위 및 유량확보와 홍수방지를 위한 보(weir)가 4대강 유역에 16개 설치되고 있다. 이러한 보 구간에는 고정보와 가동보가 복합적으로 설치되고 있으며 가동보는 그 형상과 운영방식에 따라 다양한 설계방안이 적용되었다. '4대강 살리기 사업' 중 낙동강 23공구의 강정보 공사 구간에는 원호형태의 측면 형상을 갖는 라이징 섹터게이트(Rising sector gate)가 적용되었다. 라이징 섹터게이트는 구조물의 높이가 낮고 수문의 개폐장치가 수문피어 구조물 내에 설치되어 경관이 우수하며, 구조가 간단하여 비체와 수류의 안정성이 뛰어나기 때문에 4개의 공사구간에 적용되었다. 따라서 본 연구에서는 강정보의 가동보 구간 2문 중 1문을 1/100 축척으로 제작하여 가변경사 개수로에 설치하고, 홍수 빈도별 상류 유량 조건과 하류단 수위조건으로 케이스를 정하여 실험을 수행하였다. 본 실험에서 사용한 개수로 장치는 너비 0.6 m, 높이 0.8 m, 그리고 길이 15.0 m(측정가능 구간, 헤드탱크와 테일게이트 부제외)의 개수로 실험장치이다. 측부는 모두 강화유리로 되어 육안관찰 및 계측 시 용이하게 제작되었으며, 순환식 유량 공급장치를 구축하여 수로의 하부에 설치된 유량탱크로부터 계속적으로 순환하도록 설계되었다. 또한 수로 하단으로부터 상단방향으로 약 33 m 지점에 전동 유압식 Jack screw 2기가 설치되어 경사도를 조절할 수 있도록 제작되었다. 유량조절용 판넬의 제어기판에는 디지털 경사계가 설치되어 있기 때문에 보다 정확한 경사도의 조절이 가능하다. 보 모형의 총연장은 53 cm이며 폭은 45 cm이다. 섹터게이트의 게이트부분은 직경 15 cm로 설계하였다. 문주부분을 포함한 모든 모형은 아크릴로 제작하며 레이저의 주사를 방해하지 않으며 투과율을 최대로 할 수 있도록 고강도의 아크릴을 가장 얇게 하여 중공형태를 채택하였다. 실험조건은 우선 보의 운영방안에 따라 게이트의 4가지 개방도를 설정하였고, 특히 평수위조건에서는 보의 상류부에 퇴적된 퇴적물의 세척을 위한 flushing 운영개방도 포함되어 있다. 홍수시에 대한 유량조건은 2년 빈도에 해당하는 유량을 수문의 비율과 상사법칙에 따라 설정하였으며 하류단 수위조건도 동일한 조건에 대한 값을 채택하여 적용하였다. 유동장의 해석을 위해서는 비접촉식 계측방법인 PIV(Particle Image Velocimetry) 시스템을 채택하여 2차원(x-z 방향) laser sheet를 생성하고 주입된 particle에서 반사된 변위(displacement) 정보를 상호상관(cross-correlation)기법으로 유동장을 계산하였다. 또한 수리모형과 동일한 지형격자를 구축하여 3차원 CFD 프로그램인 FLOW-3D로 계산하여 결과를 비교하였다. 특히 flushing 운영방안에 대한 게이트부의 개방도를 세가지(30, 45, $60^{\circ}$)로 구분하여 모의하였고, 적절한 개방도를 제안하고자 하였다. 실험결과는 우선 4가지 운영방안에 대한 가동보 주변에서의 유속장을 파악하였고, 최대유속의 발생위치의 변화를 확인할 수 있었다. 그리고 이에 따른 보의 바닥에서 최대유속이 발생할 경우, 하상보호공 위치와 거리 등에 대해서 분석하였다. 이를 통해 가동보 운영에 따른 다양한 유속구조를 파악할 수 있게 되며 구조적 안정성 확보를 위한 검증자료로 활용될 수 있을 것으로 예상된다. 향후, 가동보 운영방안 중 수세효과(flushing effect)에 대한 효과분석을 위해 게이트부 상류구간에 적절한 입경과 비중의 퇴적물질을 설치하는 연구와 상류부에서의 유입유사농도 및 시간변화에 따른 퇴적에 관한 연구를 수행할 계획이다.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.3
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• pp.382-389
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• 2020

Objective: This study was conducted to test the efficiency of genomic selection for milk production traits in a Korean Holstein cattle population. Methods: A total of 506,481 milk production records from 293,855 animals (2,090 heads with single nucleotide polymorphism information) were used to estimate breeding value by single step best linear unbiased prediction. Results: The heritability estimates for milk, fat, and protein yields in the first parity were 0.28, 0.26, and 0.23, respectively. As the parity increased, the heritability decreased for all milk production traits. The estimated generation intervals of sire for the production of bulls (L_SB) and that for the production of cows (L_SC) were 7.9 and 8.1 years, respectively, and the estimated generation intervals of dams for the production of bulls (L_DB) and cows (L_DC) were 4.9 and 4.2 years, respectively. In the overall data set, the reliability of genomic estimated breeding value (GEBV) increased by 9% on average over that of estimated breeding value (EBV), and increased by 7% in cows with test records, about 4% in bulls with progeny records, and 13% in heifers without test records. The difference in the reliability between GEBV and EBV was especially significant for the data from young bulls, i.e. 17% on average for milk (39% vs 22%), fat (39% vs 22%), and protein (37% vs 22%) yields, respectively. When selected for the milk yield using GEBV, the genetic gain increased about 7.1% over the gain with the EBV in the cows with test records, and by 2.9% in bulls with progeny records, while the genetic gain increased by about 24.2% in heifers without test records and by 35% in young bulls without progeny records. Conclusion: More genetic gains can be expected through the use of GEBV than EBV, and genomic selection was more effective in the selection of young bulls and heifers without test records.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.169-182
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• 2007

To evaluate the possibly potent role of Asian Dust (AD) on the long range transport of Hg, statistical analyses were carried out using the hourly concentration data of gaseous elemental mercury (Hg) along with relevant environmental parameters. For the purpose of this study, Hg data were collected from Yang-Jae monitoring station in Seoul, Korea during Sept. 1997 to June 2002. During the study period, Hg concentrations in non-AD period ranged from $0.03\;to\;32.70\;ng\;m^{-3}$ with a mean $5.27{\pm}3.06\;ng\;m^{-3}$, while those in AD period from $1.79\;to\;32.60\;ng\;m^{-3}$ with a mean $5.20{\pm}3.06\;ng\;m^{-3}$. The air quality during AD were typically deteriorated by enhanced PM10 mass concentration (by $2{\sim}5$ times) compared to non-AD period, however comparison of the Hg concentration data indicates that they are not critically distinguished between events of AD and non-AD, except for the high minimum level of Hg during AD. The results of correlation and factor analysis also indicated somewhat complex patterns; in the case of AD events, Hg and $SO_{2}$ were assorted concurrently into a same factor. Evidence collected from this study thus suggests that long-range transport of Hg, if occurring, is unlikely to raise statistically Hg concentration levels such as seen during AD event. However, in nighttime of winter season, Hg concentrations are higher during AD (along with PM10 levels) than non-AD period. Although such observations suggest the effect of long range transport on the enhancement of Hg concentrations, more deliberate analysis may be required to track down the effect of such mechanism in relation with various factors including the air mass transport route.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.570-579
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• 2008

The purpose of this study was to investigate the distribution of tensile stress of canal obturated maxillary second premolar with access cavity and notch-shaped class V cavity restored with composite resin using a 3D finite element analysis. The tested groups were classified as 8 situations by only access cavity or access cavity with notch-shaped class V cavity (S or N), loading condition (L1 or L2), and with or without glass ionomer cement base (R1 or R2). A static load of 500 N was applied at buccal and palatal cusps. Notch-shaped cavity and access cavity were filled microhybrid composite resin (Z100) with or without GIC base (Fuji II LC). The tensile stresses presented in the buccal cervical area, palatal cervical area and occlusal surface were analyzed using ANSYS. Tensile stress distributions were similar regardless of base. When the load was applied on the buccal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth with class Ⅴ cavity were slightly higher than that of the tooth without class V cavity. When the load was applied the palatal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth without class V cavity were slightly higher than that of the tooth with class V cavity.