• 한국표면공학회지
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• 제36권2호
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• pp.135-140
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• 2003

The difference in lattice parameter and thermal expansion coefficient between GaN and Si which results in many defects into the grown GaN is larger than that between GaN and sapphire. In order to obtain high quality GaN films on Si substrate, it is essential to understand growth characteristics of GaN. In this study, GaN layers were grown on Si(111) substrates by MOCVD at three different GaN growth temperatures ($900^{\circ}C$, $1,000^{\circ}C$ and $1,100^{\circ}C$), using AlN and LT-GaN buffer layers. Using TEM, we carried out the comparative investigation of growth characteristics of GaN by characterizing lattice coherency, crystallinity, orientation relationship and defects formed (transition region, stacking fault, dislocation, etc). The localized region with high defect density was formed due to the lattice mismatch between AlN buffer layer and GaN. As the growth temperature of GaN increases, the defect density and surface roughness of GaN are decreased. In the case of GaN grown at $1,100^{\circ}$, growth thickness is decreased, and columns with out-plane misorientation are formed.

• 호남수학학술지
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• 제26권4호
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• pp.463-469
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• 2004

In this paper we establish some recurrence relations satisfied by quotient moments of upper record values from the exponential distribution. Let $\{X_n,\;n{\geq}1\}$ be a sequence of independent and identically distributed random variables with a common continuous distribution function F(x) and probability density function(pdf) f(x). Let $Y_n=max\{X_1,\;X_2,\;{\cdots},\;X_n\}$ for $n{\geq}1$. We say $X_j$ is an upper record value of $\{X_n,\;n{\geq}1\}$, if $Y_j>Y_{j-1}$, j > 1. The indices at which the upper record values occur are given by the record times {u(n)}, $n{\geq}1$, where u(n)=min\{j{\mid}j>u(n-1),\;X_j>X_{u(n-1)},\;n{\geq}2\} and u(1) = 1. Suppose $X{\in}Exp(1)$. Then $\Large{E\;\left.{\frac{X^r_{u(m)}}{X^{s+1}_{u(n)}}}\right)=\frac{1}{s}E\;\left.{\frac{X^r_{u(m)}}{X^s_{u(n-1)}}}\right)-\frac{1}{s}E\;\left.{\frac{X^r_{u(m)}}{X^s_{u(n)}}}\right)}$ and $\Large{E\;\left.{\frac{X^{r+1}_{u(m)}}{X^s_{u(n)}}}\right)=\frac{1}{(r+2)}E\;\left.{\frac{X^{r+2}_{u(m)}}{X^s_{u(n-1)}}}\right)-\frac{1}{(r+2)}E\;\left.{\frac{X^{r+2}_{u(m-1)}}{X^s_{u(n-1)}}}\right)}$.

• 대한의용생체공학회:의공학회지
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• 제9권1호
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• pp.47-60
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• 1988

N-n-Propylacrylamide는 n-propyl bromide와 acrylamide로 부터 합성하였고, 합성된 N-n-propylacrylamide를 THF용매속에서 개시제로 AIBN을 사용하여 $60^{\circ}C$에서 acrylamide와 공중합시켰다. 그리고 합성된 단량체와 공중합체는 NMR과 IR에 의하여 확인하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제18권2호
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• pp.5-7
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• 2016

We present an experimental investigation of the superconducting transition temperatures, $T_c$, of superconductor/ferromagnet bilayers with varying the thickness of ferromagnetic layer. FeN was used for the ferromagnetic (F) layer, and NbN and Nb were used for the superconducting (S) layer. The results were obtained using three different-thickness series of the S layer of the S/F bilayers: NbN/FeN with NbN thickness, $d_{NbN}{\approx}9.3nm$ and $d_{NbN}{\approx}10nm$, and Nb/FeN with Nb thickness $d_{Nb}{\approx}15nm$. $T_c$ drops sharply with increasing thickness of the ferromagnetic layer, $d_{FeN}$, before maximal suppression of superconductivity at $d_{FeN}{\approx}6.3nm$ for $d_{NbN}{\approx}10nm$ and at $d_{FeN}{\approx}2.5nm$ for $d_{Nb}{\approx}15nm$, respectively. After shallow minimum of $T_c$, a weak $T_c$ oscillation was observed in NbN/FeN bilayers, but it was hardly observable in Nb/FeN bilayers.

• 한국식품영양학회지
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• 제8권2호
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• pp.59-69
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• 1995

This study designed to compare the hypolipidemic e(feats of n6 linoleic acid (LA), n3 w-linolenic acid(LL) and n3 eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) In rats fed high fat (40% Cal) diet. Male Sprague-Dawley rats fed experimental diets for 6 weeks, which were different only in fatty acid composition. The dietary fats were beef tallow (BT) as a source of saturated fatty acid (SFA), corn oil(CO) for n6 LA, perilla oil (PO) for n3 a-LL and fish oil (FO) for n3 EPA+DHA. Plasma total cholesterol (T-chol) level was increased by n6 LA but decreased by n3 LL and n3 EPA+DHA and most effectively reduced by n3 EPA+DHA. Plasma triglyceride(TG ) level was reduced by n6 LA, but lipogenesis in liver was not affected by n6 LA. However, plasma TG level was lowered by n3 LL and EPA+DHA. Both lipogenic enzyme activity and liver TG level were also decreased by n3 PUFA. PO and FO groups were significantly higher in the relative Proportions of C20:5 and C22:6 of plasma and liver and lower in those of C20:4/C20:5 ratio. Overall, the lipid-lowering effect was in the order of n3 EPA+DHA >n3 LL > n6 LA and fish oil and perilla oil rich in n3 PUFA may have important nutritional applications in the prevention and treatment of hyperlipidemia.

• 한국가축번식학회지
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• 제6권1호
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• pp.31-35
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• 1982

A study of 188 lactations of Holstein cows in Gwangju area was undertaken to establish the shape of lactation curve during the period from October in 1980 to January in 1982. The Gammafunction described by Wood(1967) was fitted to the lactations observed. The results obtained in the present study were summarized as follows; 1. The lactation curve of the 188 lactations was expressed by the equation based on Wood's model (1967) as follows; Yn=24.5m0.0762e-0.0944n(R2=0.99) 2. The lactation curves by parity were represented by the equations as follows; Yn=18.81n0.1486e-0.0741n(R2=0.98)……………parity 1 Yn=26.51n0.1161e-0.1200n(R2=0.96)……………parity 2 Yn=26.95n0.2804e-0.1703n(R2=0.99)……………parity 3 Yn=27.92n0.1429e-0.1427n(R2=0.98)……………parity 4 Yn=22.61n0.1985e-0.1211n(R2=0.94)……………parity 5 3. The lactation curves by calving seasons were represented by the equationes as follows; Yn=27.05n0.0739e-0.1005n(R2=0.98)……………spring Yn=23.08n0.2040e-0.1202n(R2=0.98)……………summer Yn=26.81n0.0460e-0.1134n(R2=0.98)……………autumn Yn=23.40n0.1299e-0.1101n(R2=0.95)……………winter

• 대한수학회지
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• 제53권6호
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• pp.1225-1236
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• 2016

Let R be a commutative ring with $1{\neq}0$ and n a positive integer. In this article, we introduce the n-Krull dimension of R, denoted $dim_n\;R$, which is the supremum of the lengths of chains of n-absorbing ideals of R. We study the n-Krull dimension in several classes of commutative rings. For example, the n-Krull dimension of an Artinian ring is finite for every positive integer n. In particular, if R is an Artinian ring with k maximal ideals and l(R) is the length of a composition series for R, then $dim_n\;R=l(R)-k$ for some positive integer n. It is proved that a Noetherian domain R is a Dedekind domain if and only if $dim_n\;R=n$ for every positive integer n if and only if $dim_2\;R=2$. It is shown that Krull's (Generalized) Principal Ideal Theorem does not hold in general when prime ideals are replaced by n-absorbing ideals for some n > 1.

• 생명과학회지
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• 제19권10호
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• pp.1417-1423
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• 2009

선행된 연구에서 나타난 n-3 지방산 결핍 식이에 DHA 첨가는 뇌 기능 개선효과가 나타났으나 n-3 지방산이 적절히 함유된 식이에 DHA 첨가는 유의적 뇌 기능 향상효과가 나타나지 않았다. 이러한 결과에 대한 설명으로 본 연구에서는 필수 지방산 함량이 다른 식이, 즉 n-3 지방산 결핍 및 적절군에 각각 DHA를 첨가하여 뇌 및 간의 지방산 조성에 미치는 영향에 대하여 검토하였다. N-3 지방산이 결핍된 식이군(Def)의 체중 및 뇌의 무게는 DHA를 첨가한 식이군(Def+DHA)이나 n-3 지방산이 적절히 함유된 식이군(Adq) 및 DHA 첨가군(Adq+DHA)에 비해 유의적으로 높았다(p<0.05). 뇌의 지방산 조성 결과에서 n-6계 지방산들 중 특히 22:5n-6의 함량이 n-3 지방산 결핍군(Def)에서 현저히 높았으며 20:4n-6 및 22:4n-6의 함량도 이 식이군(Def)에서 높았으나 18:2n-6 및 20:3n-6의 함량은 낮았다(p<0.05). 총 n-3계 지방산 및 22:6n-3의 함량은 예상했듯이 n-3 지방산 결핍군(Def)에서 가장 낮았으며 다른 식이군들과 비교했을 때 약 64% 감소됨을 살펴볼 수가 있었다. 또한 n-6/n-3의 비도 n-3 지방산 결핍군(Def)에서 3.35로 식이군들 중 유의적으로 높았다(p<0.05). 흥미로운 것은 n-3 지방산 결핍에 DHA를 첨가한 식이군(Def+DHA)의 경우, 뇌의 22:6n-3 함량이 13.1%로 n-3 지방산 적절군(Adq) 및 DHA 첨가군(Adq+DHA)과 유의적 차이가 없었다. 간의 지방산 조성 결과에서 뇌의 지방산 조성과 유사하게 n-6 지방산들 중 특히 22:5n-6의 함량이 n-3 지방산 결핍군(Def)에서 현저히 높았으며(p<0.05), n-3 적절군(Adq)의 경우, DHA 첨가군(Adq+DHA)과 비교했을 때 대부분의 n-6계 지방산의 함량이 유의적으로 높았다(p<0.05). N-3 결핍군에 DHA의 첨가군(Def+DHA)은 총 n-3계 지방산 및 22:6n-3의 함량이 n-3 결핍군(Def)에 비해 현저히 높았다(p<0.05). 특히 이 식이군(Def)의 22:6n-6의 함량은 n-3 적절군(Adq) 및 DHA 첨가군(Adq+DHA)보다 더 높은 수치를 나타내었다. 또한 n-3 지방산이 결핍된 동물(Def)의 간에서 18:3n-3의 함량을 거의 찾을 수가 없었으나 DHA 첨가군(Def+DHA)의 경우 가장 높은 함량을 나타내었다. 이는 n-3 지방산 결핍군(Def)의 경우 거의 모든 18:3n-3가 생체 내에서 고도로 불포화된 지방산으로 전환되기 위해 사용된 것으로 사료된다. 따라서 본 연구의 결과로부터 n-3 지방산이 결핍된 군의 경우 DHA 첨가로 인하여 뇌 DHA 함량 증가와 더불어 뇌 기능이 개선되었음을 살펴 볼수가 있었다. 반면 이미 뇌의 DHA가 포화상태인 n-3 지방산이 적절히 함유된 식이의 경우 DHA의 부가적인 첨가는 뇌기능 향상면에서는 유의적 효과가 나타내지 않았음을 뇌의 지방산 조성으로 확인 할 수가 있었다.

• 한국초지조사료학회지
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• 제38권2호
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• pp.140-144
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• 2018

To investigate the impact of nitrogen (N) mineral on reproductive potential of Brassica napus L, plants were treated with different levels of N treatment ($N_0$; $N_{100}$; $N_{500}$). The half of N content for each treatment were applied at the beginning of the early vegetative stage and the rest was applied at the late vegetative stage. Nitrogen content in plant tissues such as root, stem and branch, leaf, pod and seed was analyzed and harvest index (HI) was calculated as percentage of seed yield to total plant weight. Biomass and nitrogen content were significantly affected by different levels of N supply. Biomass was significantly decreased by 59.2% in nitrogen deficiency ($N_0$) but significantly increased by 50.3% in N excess ($N_{500}$), compared to control ($N_{100}$). Nitrogen content in all organs was remarkably increased with nitrogen levels. N distribution to stem and branches, and dead leaves was higher in N-deficient ($N_0$) and N excessive plants ($N_{500}$) than in control ($N_{100}$). However, nitrogen allocated to seed was higher in control ($N_{100}$) than in other treatments ($N_0$ or $N_{500}$), accompanied by higher HI. These results indicate that the optimum level of N supply ($N_{100}$) improve HI and N distribution to seed and excessive N input is unnecessary.

• Journal of Ecology and Environment
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• 제31권3호
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• pp.167-176
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• 2008

Atmospheric N deposition has far-reaching impacts on forest ecosystems, including on-site impacts such as soil acidification, fertilization, and nutrient imbalances, and off-site environmental impacts such as nitrate leaching and nitrous oxide emission. Although chronic N deposition has been believed to lead to forest N saturation, recent evidence suggests that N retention capacity, particularly in the forest floor, can be surprisingly high even under high N deposition. This review aims to provide an overview of N retention processes in the forest floor and the implications of changing C-N interactions for C sequestration. The fate of available N in forest soils has been explained by the competitive balance between tree roots, soil heterotrophs, and nitrifiers. However, high rates of N retention have been observed in numerous N addition experiments without noticeable increases in tree growth and soil respiration. Alternative hypotheses have been proposed to explain the gap between the input and loss of N in N-enriched, C-limited systems, including abiotic immobilization and mycorrhizal assimilation, both of which do not require additional C sources to incorporate N in soil N pools. Different fates of N in the forest floor have different implications for C sequestration. N-induced tree growth can enhance C accumulation in tree biomass as observed across temperate regions. C loss from forests can amount to or outweigh C gain in N-saturated, declining forests, while another type of 'C-N decoupling' can have positive or neutral effects on soil C sequestration through hampered organic matter decomposition or abiotic N immobilization, respectively.