• 한국분말재료학회지
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• 제8권2호
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• pp.104-109
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• 2001

The semiconducting ${\beta}-FeSi_2$ compound has been recognized as a thermoelectric material with excel-lent oxidation resistance and stable characteristics at elevated temperature. In the present work, we applied mechanical alloying(MA) technique to produce ${\beta}-FeSi_2$ compound using a mixture of elemental iron and silicon powders. The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-K $\alpha$ radiation, thermal analysis and scanning electron microscopy. The single ${\beta}-FeSi_2$ phase has been obtained by mechanical alloying of $Fe_{33}Si_{67}$ mixture powders for 120 hrs or for 70 hrs coupled with the subsequent heat treatment up to $700^{\circ}C$. The grain size of ${\beta}-FeSi_2$ powders analyzed by Hall plot method was 44nm.

• 한국응용과학기술학회지
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• 제6권1호
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• pp.59-66
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• 1989

Inclusion complex formation of octyldimethyl p-aminobenzoate with ${\beta}-cyclodextrin$in aqueous solution and in the solid state was studied by the solubility method, spectroscopic (UV, FT-IR) and X-ray diffractornetry. The solid complex of octyldimethyl p-aminobenzoate with ${\beta}-cyclodextrin$ was obtained in molar ratio of 1:2 (guest/host). A spatial relationship between host and guest molecule was clearly reflected in the magnitude of the apparent stability constant (K') and in the stoichiometry of the inclusion complex. Furthermore, a typical type Bs phase-solubility diagram was obtained for octyldimethyl p-aminobenzoate and ${\beta}-cyclodextrin$ in water at $25^{\circ}C$. The results indicated that the solubility of the guest molecule was higher by the formation of ${\beta}-cyclodextrin$ inclusion complex.

• 한국결정성장학회지
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• 제12권2호
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• pp.68-72
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• 2002

Iodine ($I_2$)을 이용한 기상성장법(chemical vapour transport CVT)으로 상용 FeSi$_2$분말로부터 $\beta$-$FeSi_2$ 및 $\alpha$-$FeSi_2$단결정을 제조하였다 $FeSi_2$ 분말은 iodine과 함게 석영 ampoule에 넣은 후 진공배기하여 two-zone 전기로 내에서 기상성장 시켰다. CVT법에 의한 기상성장시 고온부분의 source측 온도는 $1050^{\circ}C$이었으며 $\beta$-$FeSi_2$와 $\alpha$-$FeSi_2$ 단결정이 얻어지는 성장측 온도는 각각 $750^{\circ}C$ 및 $950^{\circ}C$이었다. 이때 얻어진$\alpha$-$FeSi_2$ 단격정은 $l0\times10 \textrm{mm}^2$크기의 판상결정이었고 orthorhombic 구조의 $\beta$-$FeSi_2$, 단결정은 길이 10mm의 needle형 결정임을 알 수 있었다. $\alpha$-$FeSi_2$ 단결정의 조성을 EPMA로 조사한 결과 Si이 화학양론비보다 많은 $FeSi_{2.58}$ 이었다. CVT법으로 합성된 $\beta$-$FeSi_2$ 격정의 승온에 따른 상의 안정성을 조사한 결과 $930^{\circ}C$ 이상에서 $\alpha$-$FeSi_2$로 상변태함을 알 수 있었다.

• Journal of Animal Science and Technology
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• 제59권7호
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• pp.19.1-19.10
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• 2017

Background: To reduce use of main feed ingredient like corn, soy bean meal (SBM) and wheat, alternative ingredients has been studied like copra meal (CM). Production amount of CM which has been high makes CM to be an alternative feed stuff. However, low digestibility on AA and low energy content by high fiber content can be an obstacle for using CM. This experiment was conducted to evaluate the effects of CM supplementation with ${\beta}$-mannanase on growth performance, blood profile, nutrient digestibility, pork quality and economic analysis in growing-finishing pigs. Methods: A total of 100 growing pigs ([Yorkshire ${\times}$ Landrace] ${\times}$ Duroc) averaging $31.22{\pm}2.04kg$ body weight were allotted to 5 different treatments by weight and sex in a randomized complete block (RCB) design in 5 replicate with 4 pigs per pen. Treatments were 1) Control (corn-SBM based diet + 0.1% of ${\beta}$-mannanase (800 IU)), 2) CM10 (10% copra meal + 0.1% ${\beta}$-mannanase (800 IU)), 3) CM15 (15% copra meal + 0.1% ${\beta}$-mannanase (800 IU)), 4) CM20 (20% copra meal + 0.1% ${\beta}$-mannanase (800 IU)) and 5) CM25 (25% copra meal + 0.1% ${\beta}$-mannanase (800 IU)). Four phase feeding program was used: growing I (week 1-3), growing II (week 4-6), finishing I (week 7-9) and finishing II (week 10-12). Results: In growth performance, there was no significant difference among treatments during whole experimental period. In growingI phase, G:F ratio tended to increase when CM was increased (P = 0.05), but ADG and ADFI tended to decrease in finishingII phase (linear, P = 0.08). Also, increasing CM reduced ADG (linear, P = 0.02) and feed efficiency (linear, P = 0.08) during the whole finishing period. In blood profiles, BUN was linearly increased as CM increased (linear, P = 0.02) at growingII period. In digestibility trial, there was no significant difference in dry matter, crude fat, crude ash and nitrogen digestibility. However, crude protein digestibility was decreased linearly (linear, P = 0.02). In economic analysis, feed cost per weight gain and total feed cost per pig were reduced in overall period when CM was provided by 25% (linear, P = 0.02). Conclusion: CM with 0.1% of ${\beta}$-mannanase (800 IU) could be supplemented instead of corn and SBM up to 25% without detrimental effects on growth performance and pork quality of growing-finishing pigs.

• 한국가축번식학회지
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• 제13권2호
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• pp.85-92
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• 1989

The study was carried out to find out the changes of the sex hormone concentrations in the blood plasma and antrum of follicular and lutein cystic ovaries of Holstein cows. The progesterone, estradiol-17$\beta$, testosterone, FSH and LH from samples of the blood plasma and antrum of cystic ovaries of cows assayed by radioimmunoassay method. The results of this study were summarized as follows : 1. The concentrations fo progesterone and estradiol-17$\beta$ in the blood plasmaat estrous and luteal phase were 0.95$\pm$0.18ng/ml, 11.45$\pm$3.12pg/ml and 4.25$\pm$0.27ng/ml, 6.27$\pm$0.82pg/ml respectively. The concentrations of progesterone and estradiol-17$\beta$ in the antrum fluid of follicles at estrous and luteal phase were 24.8$\pm$4.12ng/ml, 54.3$\pm$7.25pg/ml and 21.7$\pm$3.79ng/ml, 14.3$\pm$2.72pg/ml respectively, and showed significant changes among the estrous and luteal phase and blood plasma and antrum fluid of follicles. 2. The concentrations of progesterone, estradiol-17$\beta$, testosterone and LH in the blood plasma of follicular cystic ovareis of cows were 0.85$\pm$0.25ng/ml, 9.23$\pm$2.72pg/ml, 17.12$\pm$3.26pg/ml and 3.78$\pm$1.02mIU/ml respectively. And the concentrations of progesterone, estradiol-17$\beta$, testosterone and LH in the antrum fluid of follicular cystic ovareis of cows were 284$\pm$48.21ng/ml, 389$\pm$67.23ng/ml, 12.84$\pm$0.29ng/ml and 1.84$\pm$0.17mIU/ml respectively, and showed significant changes between in the blood plasma and antrum fluid of cystic ovaries. 3. The concentrations of progesterone, estradiol-17$\beta$, testosterone and LH in the blood plasma of lutein cystic ovaries of cows were 3.40$\pm$0.78ng/ml, 4.02$\pm$0.42pg/ml, 10.72$\pm$2.74pg/ml and 0.76$\pm$0.12mIU/ml respectively. And the concentrations of progesterone, estradiol-17$\beta$, testosterone and LH in the antrum fluid of lutein cystic ovareis of cows were 427$\pm$35.79ng/ml, 0.76$\pm$0.07ng/ml, 3.45$\pm$0.57ng/ml and 0.29$\pm$0.07mIU/ml respectively, and showed significant changes between the blood plasma and antrum fluid of cystic ovaries. 4. Accordingly, the diagnosis of follicular and lutein cystic ovareis of cows from progesterone, estradiol-17$\beta$ and LH levels in the blood plasma and antrum of cystic ovaries of cows is thought to be possible a diagnostic means.

• 생명과학회지
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• 제17권3호통권83호
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• pp.407-411
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• 2007

효소생산을 최적화하기 위해서 Paenibacillus sp. DG-22에서의 ${\beta}-xylosidase$ 생합성 조절을 연구하였다. Paenibacillus sp. DG-22의 ${\beta}-xylosidase$는 배양액에 존재하는 탄소원에 의해 조절되는 것으로 관찰되었다. ${\beta}-Xylosidase$의 합성은 xylan과 methyl ${\beta}-D-xylopyranoside$ (${\beta}MeXyl$)에 의해 유도되었으나 쉽게 대사되는 단당류에 의해서는 약간 억제되었다. ${\beta}MeXyl$가 ${\beta}-xylosidase$의 유도를 위한 최적의 기질임을 확인하였고 가장 효과적인 유도는 10 mg/ml의 농도에서 얻어졌다. ${\beta}-Xylosidase$의 생산은 세포의 생장과 연관된 양상을 나타내었으며, 대수기 말에 최대양이 형성되었다. Glucose와 xylose가 존재하면 ${\beta}-xylosidase$의 활성 수준이 감소하는 것으로 보아 이 효소의 생합성은 catabolite repression을 받는것으로 보인다. SDS-PAGE와 활성염색 기술을 이용하여 ${\beta}Mexyl$가 이 효소의 생합성을 유도하며 약 80 kDa 크기의 하나의 ${\beta}-xylosidase$가 존재함을 알 수 있었다.

• 한국식품영양과학회지
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• 제36권1호
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• pp.117-123
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• 2007

본 연구에서는 단체급식에서 많이 이용되는 시금치의 조리방법에 따른 카로티노이드 분리 및 정량을 위해서 HPLC를 이용하여 분석하였다. 시금치의 methanol 추출물로 THF 용매 분획물에 대하여 카로티노이드 및 그 이성체 화합물을 표준품으로 해서 분리된 카로티노이드의 RT와 함량은 lutein(63%), zeaxanthin(2.1%), crytoranthin, 13-cis-$\beta$-carotene(1.8%), a-carotene, trans-$\beta$-carotene(29.6%), 9-cis-$\beta$-carotene(3.1%)의 순으로 분리되었으며, 여기서 분리된 crytoxanthin은 미량 검출되어 본 실험에서는 정량하지 않았다. Lutein은 다른 카로티노이드에 비하여 조리방법 및 가열에 의한 영향을 비교적 덜 받는 것으로 나타났고, zeaxanthin은 조리 후 감소하는 경향을 보였다. 한편, trans-cis-$\beta$-carotene의 이 성 체 인 9-cis-$\beta$-carotene과 1,3-cis-$\beta$-carotene은 조리방법과 상관없이 가열 후 증가하는 경향을 보였는데 이는 가열과정이 trans-$\beta$-carotene의 이성화를 형성시키는 것으로 설명된다. Steam 조리 및 냉동 후 microwave조리에서 trans-$\beta$-carotene은 증가하는 경향을 보였다(p<0.05). 시금치의 총 non-provitamin A의 경우, 각 처리구간에 별 차이가 없었으나, 총 provitamin A에서는 원재료와 냉동 후 조리에서 유의적 차이를 볼 수 있었다(p<0.05). 또한 provitamin A로서의 기능이 가장 큰 trans-$\beta$-carotene은 steam으로 가열한 경우 가장 높았으며 또한 카로티노이드의 총 함량도 다른 시료보다 높은 함량을 보여주었다. 그 다음은 냉동 후 microwave로 가열한 시료로 두 시료와 유의적인 차이를 보였다(p<0.05). 이상의 결과로부터 steam 가열시료, 냉동 후 가열시료, 원재료를 microwave로 가열한 시료 그리고 원재료 시금치의 순으로 카로티노이드의 총 함량이 높게 나타났다.

• 대한화학회지
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• 제31권4호
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• pp.315-321
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• 1987

우라늄 추출을 위한 리간드를 페닐알라닌과 3-oxoglutaric acid로 부터 합성하였다. 여러가지 pH, 리간드와 우라늄의 여러 농도비에서 리간드를 녹인 이염화메탄 용액을 사용하여 우라늄 추출 실험을 한 결과, pH 8에서 최대의 추출효율이 나타났으며, 리간드와 우라늄의 농도비가 커질수록 추출율이 증가하였고, 농도비가 4이상에서 완전추출이 되었다. 또한 다른 양이온들과의 경쟁반응에서 리간드가 우라늄에 대해 높은 선택성을 나타내는 것이 확인 되었으며, 추출된 우라늄이 1M 염산용액에 정량적으로 회수되었고 리간드도 재사용 할 수 있었다. 그리고 우라닐 이온과 리간드의 안정도 상수를 측정 하였으며, 총괄 생성상수 값들은 다음과 같다. ${\beta}_1=1.20{\times}10^5\;,\;{\beta}_2=1.01{\times}10^8$.

• 한국세라믹학회지
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• 제36권10호
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• pp.1094-1101
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• 1999

Liquid phase sintered silicon carbides were obtained by sintering of $\alpha$-SiC and $\beta$-SiC powders as starting materials at 2173K and 2273K respectively. The SiCplatelet seeds of different sizes were obtained by a repeated ball milling and sedimentation. Their mean size (d50) were 2.217 ${\mu}{\textrm}{m}$ 13.67 ${\mu}{\textrm}{m}$, 22.17${\mu}{\textrm}{m}$ respectively 6wt%Al2O3-4 wt% Y2O3 was used as the sintering additives for the liquid phase sintering. The two silicon carbides had a bimodal microstructure consisting of small matrix grains and large platelike grains when the SiCplatelet seeds were added. In the case of the $\beta$-SiC the appreciable phase transformation occurred as sintering temperature increased from 2173K to 2273K and resulted in matrix shape change from equiaxed into platelike grains. In contrast there was no shape change for the $\alpha$-SiC. The size of large grains in the $\alpha$-SiC of large grains in the $\alpha$-SiC was larger than that of the large grains in the $\beta$-SiC These results suggested that the growth of the $\alpha$-SiCplatelet in the $\alpha$-SiC matrix was more favored than that of the $\alpha$-SiCplatelet in the $\beta$-SiC matix. The three point flexural strength decreased as the added seed size increased. Fracture toughness values of samples sintered at 2273K were higher than those of samples sintered at 2173K.

• 한국결정성장학회지
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• 제6권3호
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• pp.386-391
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• 1996

$Si_{3}N_{4}$에 평균입경이 270 nm인 SiC 분말을 0, 10, 20, 30, 40 vol% 첨가하여 고온 가압소결법으로 $Si_{3}N_{4}/SiC$ 초미립복합재료를 제조하였다. 소결후 기지상인 ${\alpha}-Si_{3}N_{4}$는 ${\beta}-Si_{3}N_{4}$로 상전이하였으며, 이차상인 ${\beta}-SiC$는 변화가 없었다. 소결조제의 첨가에 의한 입계결정상은 검출되지 않았다. SiC의 첨가량이 많아짐에 따라 $Si_{3}N_{4}$ 결정립성장은 억제되어 미세한 결정입이 나타났으며, 작은 임자는 기지상 임내에 큰 SiC는 임계에 존재하였다. SiC 첨가에 따라 파괴강도는 약간 증가후 감소하였으며, 파괴인성은 감소하였고, 경도는 직선적으로 증가하였다.