• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.185-190
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• 1992

ACI318-89 Recommended that when the specified compressive strength of concrete in a column is greater than1.4 times that specified for a floor system, top surface of the column concrete shall extend 2ft(600mm)into the slab from the face of column to avoid unexpected brittle failure. The major variables are extension distance, flexural strength ratio(Mr), and shear reinforcement ratio(Vs). Test results are as follows ; (1) The failure modes of specimens under cyclic loading were concentrated at critical region from beam-column joint face. (2) Ductility index($\mu$f) were increased with increasing of shear confinement ratio and flexural strength ratio. (3)The specimens with 2ft extension distance showed more ductility than the specimens with 1ft extension distance.

• 한국진공학회지
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• 제15권4호
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• pp.374-379
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• 2006

본 연구에서는 전계 방출소자로 사용하기 위한 탄소나노튜브의 합성 방법으로, pin to plate type의 대기압 플라즈마 소스를 사용한 AP-PECVD(Atmosphere pressure plasma enhanced chemical vapor deposition)를 이용하였으며, 이를 통하여 대기압에서 성장된 탄소나노튜브의 구조적 및 전기적 특성을 연구하였다. 유리 / 크롬 / 니켈을 기판으로 사용하여 $400{\sim}500^{\circ}C$ 변화 영역에서 탄소나노튜브를 성장시킨 결과 다중벽 탄소나노튜브가 얻어짐을 알 수 있었다. $500^{\circ}C$에서 성장시킨 탄소나노튜브의 경우 FT-Raman을 이용한 분석 결과 $I_D / I_G$ ratio 가 0.772 임을 관찰하였으며 TEM으로 분석결과, 내부의 그래파이트층은 15 - 20 층, 내부 직경은 10-15nm, 외부 직경은 30 - 40nm 이고, 각 층간의 간격은 0.3nm 임을 알 수 있었다. 또한 전계 방출 문턱전압은 $2.92V/{\mu}m$ 이고, FED 에서 요구되는 $1mA/cm^2$의 방출전류밀도는 $5.325V /{\mu}m$의 문턱전압 값을 가지는 것을 관찰하였다.

• 한국유기농업학회지
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• 제18권1호
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• pp.63-74
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• 2010

본 연구는 유기액비 관비가 '녹광(세미니스)' 고추의 생육과 수량에 미치는 영향을 구명코자 실시하였다. 유기액비 조성에 따라 대조구(화학비료시비), 유기액비 I(계분 : 어분 : 대두박, 2:1:1), 유기액비 II(계분 : 골분 : 대두박, 2:1:1), 유기액비 III(계분 : 골분, 1:1), 유기액비 IV(계분 : 쌀겨 : 대두박, 2:1:1) 등 5처리를 두었다. 유기액비 조성재료와 비율에 따른 액비의 pH와 EC는 각각 6.5~6.8와, $2.91{\sim}3.69dS{\cdot}m^{-1}$의 분포를 나타냈다. 유기액비 조성 비율에 따른 C/N율은 유기액비 IV가 5.75로 가장 높았으며, 그 외 처리는 처리간에 차이가 없었다. 주당 총과중은 유기액비 IV 처리구에서 1,558g으로 가장 무거웠으며 총과수는 대조구에 비해 23.7% 증가하였다. 홍고추의 캡사이신 함량은 유기액비 I과 II에서 대조구에 비하여 증가하였으며, 유기액비 III과 IV 관비구에서는 감소하였다. 당도는 유기액비 IV 관비구에서 $10.0^{\circ}Brix$로 가장 높았다.

• 음성과학
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• 제15권2호
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• pp.33-51
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• 2008

Difference of learner speech and loanword phonology is investigated in terms of Korean learners' speech and their loanword adaptation of English words with a post-vocalic word-final stop. When we compared the speech of 12 Korean learners in mid-intermediate level with that of eight English speakers, the learner speech did not reflect loanword phonology of the vowel insertion after a voiced word-final stop (e.g., rib$[\dotplus]$, bad$[\dotplus]$, gag$[\dotplus]$ vs. tip[=], cat[=], book[=]), but, instead, the target phonology of vowel lengthening before a voiced word-final stop (e.g., rib[r.I:b], CAD$[k{\ae}:d]$, bag$[b{\ae}:g]$ vs. rip[rI.p], cat$[k{\ae}t]$, back$[b{\ae}k])$. A longitudinal study of learner speech before and after instruction showed some development toward the acquisition of target phonology. The results indicate that learner speech departs from loanword phonology, and approaches to target speech in a faster rate than direct ratio. Thus, native phonology predicts loanword phonology, but lends little support to learner speech. Our results also indicate that loanword phonology is constant, while learner speech changes toward the acquisition of target phonology.

• Asian-Australasian Journal of Animal Sciences
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• 제26권4호
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• pp.573-578
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• 2013

A total of 720 1-d-old male broilers (Arbor Acres) with the initial BW = $45{\pm}2$ g were used in a 32-d experiment. Birds were randomly allotted into 1 of 4 treatments according to a completely random block design. Dietary treatments included: i) CON (basal diet), ii) ANT (CON+0.5 g antibiotics/kg feed (bacitracin methylene disalicylate)), iii) BP1 (CON+0.25 bacteriophage/kg feed), and iv) BP2 (CON+0.5 g bacteriophage/kg feed). The BWG and FI were not affected by dietary treatments throughout the whole experiment, whereas BP2 treatment reduced (p<0.05) the feed conversion ratio compared with the CON treatment during 0 to 14 d. The birds fed bacteriophages at the level of 0.25 g/kg increased (p<0.05) the relative liver weight. The inclusion of antibiotic and bacteriophage significantly reduced (p<0.05) the Escherichia coli and Salmonella concentration in the excreta compared with the NC group. Broilers fed the BP2 treatment had higher (p<0.05) lactobacillus counts compared with those fed NC and PC treatments. In conclusion, dietary supplementation of 0.5 g/kg bacteriophages increased feed efficiency and liver weight without effects on the breast muscle properties; also pathogens were inhibited by addition of bacteriophages.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.156-156
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• 2016

The effect of nitrogen doping on the mechanical and tribological performance of single-layer tetrahedral amorphous carbon (ta-C:N) coatings of up to $1{\mu}m$ in thickness was investigated using a custom-made filtered cathode vacuum arc (FCVA). The results obtained revealed that the hardness of the coatings decreased from $65{\pm}4.8GPa$ to $25{\pm}2.4GPa$ with increasing nitrogen gas ratio, which indicates that nitrogen doping occurs through substitution in the $sp^2$ phase. Subsequent AES analysis showed that the N/C ratio in the ta-C:N thick-film coatings ranged from 0.03 to 0.29 and increased with the nitrogen flow rate. Variation in the G-peak positions and I(D)/I(G) ratio exhibit a similar trend. It is concluded from these results that micron-thick ta-C:N films have the potential to be used in a wide range of functional coating applications in electronics. To achieve highly conductive and wear-resistant coatings in system components, the friction and wear performances of the coating were investigated. The tribological behavior of the coating was investigated by sliding an SUJ2 ball over the coating in a ball-on-disk tribo-meter. The experimental results revealed that doping using a high nitrogen gas flow rate improved the wear resistance of the coating, while a low flow rate of 0-10 sccm increased the coefficient of friction (CoF) and wear rate through the generation of hematite (${\alpha}-Fe_2O_3$) phases by tribo-chemical reaction. However, the CoF and wear rate dramatically decreased when the nitrogen flow rate was increased to 30-40 sccm, due to the nitrogen inducing phase transformation that produced a graphite-like structure in the coating. The widths of the wear track and wear scar were also observed to decrease with increasing nitrogen flow rate. Moreover, the G-peaks of the wear scar around the SUJ2 ball on the worn surface increased with increasing nitrogen doping.

• 한국세라믹학회지
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• 제40권5호
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• pp.468-474
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• 2003

안정화 PAN(Polyacronitrile)계 섬유를 이용하여 물리적인 방법과 화학적인 방법으로 활성탄소섬유(Activated Carbon Fibers)를 제조하고, 그 특성을 비교평가 하였다. 본 연구에서는 안정화 PAN계 섬유를 수증기 및 $CO_2$를 이용한 물리적 활성화와 KOH를 이용한 화학적 활성화에 의해 여러 등급의 활성탄소섬유를 제조하였고, 비표면적, 요오드흡착량, 미세구조, 세공구조 등을 측정하였다. 물리적 활성화 방법에는 수증기와 $CO_2$가 사용되었는데, 수증기활성화의 경우 99$0^{\circ}C$의 활성화 온도에서 1635 m$^2$/g의 비표면적을 나타내었고, $CO_2$ 활성화의 경우에는 99$0^{\circ}C$의 활성화 온도에서 671 m$^2$/g의 비표면적을 나타내었다. KOH를 이용한 화학적 활성화 방법에서는 KOH와 안정화 PAN계 탄소섬유의 비가 1.5 : 1인 경우 90$0^{\circ}C$의 활성화 온도에서 3179 m$^2$/g의 비표면적을 나타내었다. 물리적 활성화와 화학적 활성화로 제조된 활성탄소섬유의 질소흡착등온선의 결과로 보면 type I의 형태와 type I에서 type II로의 전이형태의 등온흡착곡선을 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권3호
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• pp.388-395
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• 2009

The current study was conducted to investigate the effect of early feed restriction (FR, 8 to 14 d of age) on growth performance and immune function in broiler chickens. Birds were fed corresponding diets from 3 to 35 d of age, which consisted of three phases: starter (3 to 7 d of age), FR (8 to 14 d of age) and re-alimentation (15 to 35 d of age) phases. During the FR period, each group of birds was fed the basal diet ad libitum (CON), 85% (EN85) and 70% (EN70) of lower calorie diet ad libitum (qualitative FR), and 85% (FI85) and 70% (FI70) of voluntary intake on a daily basis (quantitative FR). As a result, there was no statistical difference in weight gain, feed intake and feed conversion ratio between the CON and quantitative or qualitative FR groups during the entire (3 to 35 d) periods. In particular, the EN85 group resulted in a significant (p<0.05) increase in weight gain compared with the EN70, FI85 and FI70 groups. Plasma total protein and albumin at 14 d of age (during FR) were significantly (p<0.05) lower in the quantitative and qualitative FR groups, but these parameters at 35 d of age (after re-alimentation) were higher (p<0.05) in the EN85 and EN70 groups than in the CON group. Plasma IgG level was unaffected by dietary FR procedure. In cytokines, there was no significant difference in the expression of lymphocytic IL-4 and IFN-${\gamma}$ at 14 d of age between the FR and the CON groups, whereas lymphocytic IL-6 and iNOS expression were significantly (p<0.05) lower in FI85 and FI70 groups. Moreover, lymphocytic iNOS was also significantly (p<0.05) lower in birds fed qualitative and quantitative diets compared with those fed ad libitum. In the thymus, IL-4 expression was higher (p<0.05) in FI85 and FI70 groups, whereas IL-6 expression was lower (p<0.05) in the FI85 and FI70 groups than in the CON group. Thymic iNOS was significantly (p<0.05) lower in birds fed qualitatively and quantitatively restricted diets compared with those fed ad libitum. At 35 d of age, there was no difference in the expression of IL-4, IL-6 and IFN-${\gamma}$ of lymphocytes and thymus between the FR and CON groups. In conclusion, 85% of quantitative and qualitative FR would have a beneficial effect on the expression of some cytokines including IL-4 and iNOS without change in growth performance of birds.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1123-1125
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• 2002

In this paper, interleaved boost converter is applied as a pre-regulator in switch mode power supply. Interleaved Boost Power Factor Preregulator (IBPFP) can reduce input current ripple as a simple voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. IBPFP can be classified as three cases from duty ratio condition in continuous current mode and be carried out state space averaging small signal modeling. According to modeling, the PID controller is applied and voltage control loop is constructed for suitable design condition. From frequency domain analysis, it is verified that control system is satisfied with design condition of switch mode power supply.

• Communications for Statistical Applications and Methods
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• 제10권1호
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• pp.135-144
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• 2003

This work is concerned with comparison of the recently developed disparity measures for the partial association model in three dimensional categorical data. Data are generated by using simulation on each term in the log-linear model equation based on the partial association model, which is a proposed method in this paper. This alternative Monte Carlo methods are explored to study the behavior of disparity measures such as the power divergence statistic I(λ), the Pearson chi-square statistic X$^2$, the likelihood ratio statistic G$^2$, the blended weight chi-square statistic BWCS(λ), the blended weight Hellinger distance statistic BWHD(λ), and the negative exponential disparity statistic NED(λ) for moderate sample sizes. We find that the power divergence statistic I(2/3) and the blended weight Hellinger distance family BWHD(1/9) are the best tests with respect to size and power.