• 대한화학회지
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• 제24권2호
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• pp.108-114
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• 1980

정전기적모델과 결합의 단순한 부가성을 이용하여 아주 극성인 화합물의 표준생성열$({\Delta}H_f\;^{\circ})$를 계산하는 간단한 방법을 제안하였다. 이 ${\Delta}H_f\;^{\circ}$에 대한 할로메탄의 bond 기여도는 각각 ${\Delta}H_f\;^{\circ}(C-F)=-36.44\;kcal/mole,\;{\Delta}H_f\;^{\circ}(C-Cl)=-2.57\;kcal/mole,\;{\Delta}H_f\;^{\circ}(C-Br)=5.32\;kcal/mole,\;{\Delta}H_f\;^{\circ}(C-I)=19.18\;kcal/mole,\;and\;{\Delta}H_f\;^{\circ}(C-H)=-3.61\;kcal/mole$로 얻어졌고 이 갑들과 정전기적 에너지들로부터 계산한 ${\Delta}H_f\;^{\circ}$는 실험치와 잘 일치함을 보였다.

• Nuclear Engineering and Technology
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• 제13권3호
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• pp.145-152
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• 1981

산화제 첨가없이 고온동위원소 교환법으로 오르토 요오도히퓨린산(OIH)을 방사성요오드로 표지하면 효과적이라고 하나 그 교환메카니즘은 불확실하였다. 본 연구에서는 OIH와 $^{125}$/ $I^{-}$ 및 OIH와 $^{125}$/ $I_2$사이의 동위원소 교환반응을 두 다른 온도에서 진행시켜 교환속도 상수와 활성화파라미터들을 방사종이 크로마토그래피법으로 측정함으로써 반응속도론적으로 고찰하였다. OIH표지반응 때의 부산물로 알려진 오르토요오도벤조산(OIB)에 대해서도 같은 방범으로 진행시켰던바 교환속도 상수가 큰 순서는 OIB...$^{125}$/ $I^{-}$>OIB...$^{125}$/ $I_2$>OIH..$^{125}$/ $I^{-}$>OIH...$^{125}$/ $I_2$이었고 OIH의 활성화 파라미터가 일반적으로 OIB의 그것들보다 컸다. ($\Delta$H$\neq$$_{OIH}$>$\Delta$H$\neq$$_{OIB}$, $\Delta$S$\neq$$_{OIH}$>$\Delta$S$\neq$$_{OIB}$). 조건에 따라서는 친전자적 교환메카니즘도 가능하겠으나 위의 결과는 고온 교환반응에서 친핵적 교환메카니즘이 압도적임을 말해주었다. 그와같은 원인은 OIH의 CONHC $H_2$COOH의 오르토치환기 효과에 의한 수소결합형 전이상태 생성이 용이하기 때문이라고 보았다. 따라서 고온 교환법은 환원제가 함유되지 않은 $^{131}$ I가 생산되지 않는 작은 연구기관에서의 Hippuran표지 화합물 제조에 효과적임을 알수 있었다. 알수 있었다.

• Journal of applied mathematics & informatics
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• 제40권3_4호
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• pp.619-632
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• 2022

In this study, we examine rough ${\Delta}\mathcal{I}$-statistical convergence for difference sequences as an extension of rough convergence. We investigate the set of rough ${\Delta}\mathcal{I}$-statistical limit points of a difference sequence and analyze the results with proofs.

• 대한한방내과학회지
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• 제19권1호
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• pp.157-167
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• 1998

Background and Purpose : Cerebrovascular reactivity(CVR) can be estimated by measuring the change of cerebral blood flow that occurs during vasostimulation. To estimate the cerebrovascular reactivity, we investigated the change of flow velocity of the middle cerebral artery(MCA) during hyperventilation and hypoventilation with the transcranial doppler. So we studied whether the CVR measured by this method could show a significant difference between the normal and the cerebral infarction subjects and whether the CVR may decrease with age in normal subjects. Methods : Using transcranial doppler, we measured the mean velocity(Vm), the pulsatility index(P.I.) at the resting state, the end of breath-holding and the end of hyperventilation in 36 normal and 10 cerebral infarction subjects, so we calculated the percentile change of mean velocity(%${\Delta}$Vm) and P.I.(%${\Delta}$P.I.) after the vasostimulation. We estimated the change of Vm, P.I., %${\Delta}$Vm and %${\Delta}$P.I. by the age group and compared those parameters between the age-matched normal control and cerebral infarction subjects. Results : The Vm in MCA significantly decreased with age(p<0.05), but there was no significant difference in Vm and P.I. between normal and cerebral infarction subjects. The %${\Delta}$Vm and %${\Delta}$P.I. in response to hyperventilation significantly decreased with age in MCA and there was significant difference in $%{\Delta}Vm$ of MCA after breath-holding between the normal and cerebral infarction subjects. Conclusion : The breath-holding and hyperventilation tests could be non-invasive and useful methods in estimation of the cerebrovascular reactivity and could be applied in the basal and follow-up evaluation of the cerebrovascular reserve of the ischemic stroke patients.

• 대한수학회논문집
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• 제33권1호
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• pp.85-101
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• 2018

Let S be a polynomial ring over a field K, with a monomial order ${\prec}$, and let I be an unmixed graded ideal of S. In this paper we study two functions associated to I: The minimum distance function ${\delta}_I$ and the footprint function $fp_I$. It is shown that ${\delta}_I$ is positive and that $fp_I$ is positive if the initial ideal of I is unmixed. Then we show that if I is radical and its associated primes are generated by linear forms, then ${\delta}_I$ is strictly decreasing until it reaches the asymptotic value 1. If I is the edge ideal of a Cohen-Macaulay bipartite graph, we show that ${\delta}_I(d)=1$ for d greater than or equal to the regularity of S/I. For a graded ideal of dimension ${\geq}1$, whose initial ideal is a complete intersection, we give an exact sharp lower bound for the corresponding minimum distance function.

• 대한수의학회지
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• 제38권1호
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• pp.9-15
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• 1998

To investigate the involvement of protein kinase C(PKC) isoenzyme in the testes which control spermatogenesis and hormone secretion, we examined cellular distribution of four types of PKC $\alpha$, ${\beta}I$, ${\delta}$ and ${\theta}$ in the horse testes using PKC antisera by western blot analysis and immunohistochemistry. By the western blot analysis, PKC $\alpha$ and ${\beta}I$ were detected at 82KD, while PKC ${\delta}$ and ${\theta}$ were detected at 80KD in the testes of both juvenile and adult horses. In juvenile horse, PKC $\alpha$, ${\delta}$ and ${\theta}$ except ${\beta}I$ were not detected in the cells of the testes, whereas PKC ${\beta}I$ was immunoreacted with only in spermatocytes. In adult, PKC $\alpha$, ${\beta}I$, ${\delta}$ and ${\theta}$isoenzymes were localized in interstitial cells of the testes. In the seminiferous tubules, PKC ${\beta}I$ is localized in spermatocyte, spermatid and spermatozoa, while PKC ${\delta}$ is localized only in spermatids. We suggest that this is a first report to localize PKC in the testes of horse and PKC isoenzymes are upregulated in the cells of horse testes depending on ages. These findings also suggest that certain PKC isoenzyme plays an important role in the signal transduction of spermatogenic cells and interstitial cells in horse testes.

• 대한화학회지
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• 제7권3호
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• pp.211-215
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• 1963

Inter-relationship between the Hammett equation and the linear enthalpy-entropy effect has been discussed by deriving a new set of equations; ${\Delta}{\Delata}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^{\neq}$ and ${\Delta}{\Delta}F^{\neq}=a{sigma}+(b-T){\Delta}{\Delta}S^{\neq}$ where a = -1.36p. Theoretical analysis show that the Hammett, Leffler and Brown equations are special limited forms of these general equations. A necessary and sufficient test of substituent effect can thus be provided by the plot of $({\Delta}{\Delta}H^{\neq}-a{\sigma)$ versus ${\Delta}{\Delta}S^{\neq}$.

• 자원환경지질
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• 제27권3호
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• pp.219-229
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• 1994

The Sangra Pb-Zn deposit is located in the Gampo area. Most Cretaceous sedimentary rocks and Paleogene felsic intrusives in the study area have experienced intense propylitization. Such propylitization and Pb-Zn mineralization in ore veins are involved with the fluid having very low oxygen isotopic composition.Sulfurisotopic equilibrium temperature during the main Pb-Zn mineralization (late stage I) is calculated as $T=275^{\circ}{\sim}295^{\circ}C$. Oxygen and sulfur fugacity in late stage I fluid is estimated as $logfO_2=-34.4{\sim}-29.1$ and $logfS_2=-12.0{\sim}-8.2$ bars. It is inferred that the sulfur isotopic composition oflate stage I fluid was very high such as ${\delta}^{34}S_{{\Sigma}S}=+22.4{\sim}+22.5$‰ and the origin of sulfur was ocean water sulfate. Oxygen and hydrogen isotopic composition of water in ore-forming fluid was gradually increased and more abundantly affected by ocean water from early to late mineralization stage as follows; (late stage I) ${\delta}^{18}O_{H2O}=-7.2{\sim}-1.1$‰, ${\delta}D_{H2O}=-87{\sim}-84$‰, (stage II) ${\delta}^{18}O_{H2O}=-2.4{\sim}-0.8$‰, ${\delta}D_{H2O}=-39{\sim}-21$‰ (stage III) ${\delta}^{18}O_{H2O}=+0.7{\sim}+12.6$‰, ${\delta}D_{H_2O}=-49{\sim}-42$‰. The pH in ore-forming fluid was about 4.7 during late stage I and is thought to have been gradually decreased from late stage I to stage II mineralization.

• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.279-292
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• 2011

In this paper, we consider anti-periodic solutions of the following BAM neural networks with multiple delays on time scales: $$\{{x^\Delta_i(t)=-a_i(t)e_i(x_i(t))+{\sum\limits^m_{j=1}}c_{ji}(t)f_j(y_j(t-{\tau}_{ji}))+I_i(t),\atop y^\Delta_j(t)=-b_j(t)h_j(y_j(t))+{\sum\limits^n_{i=1}}d_{ij}(t)g_i(x_i(t-{\delta}_{ij}))+J_j(t),}\$$ where i = 1, 2, ..., n,j = 1, 2, ..., m. Using some analysis skills and Lyapunov method, some sufficient conditions on the existence and exponential stability of the anti-periodic solution to the above system are established.

• 한국세라믹학회지
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• 제40권5호
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• pp.455-459
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• 2003

LPE(Liquid Phase Epitaxial)법을 이용하여 성장시킨 B $i_2$S $r_2$Ca(C $u_{1-x}$ N $i_{x}$ )$_2$ $O_{8+}$$\delta$/ 막(film)을 break junction 법을 이용하여 터널링 분광을 측정하였다. Ni 조성비 $\chi$$_{L}$의 증가에 따라 에너지 간격 2$\Delta$의 크기는 증가하였다. 에너지 간격 2$\Delta$(4.2 K)는 54.4~64 meV, 2$\Delta$/ $k_{B}$ $T_{c}$ $^{zero}$는 7.36~10.14로 BCS 이론에 의한 값 보다 큰 결과를 얻었다. 융액(melting solution) 속의 Ni 조성비 $\chi$$_{L}$의 증가에 따라, 임계온도 $T_{c}$ $^{zero}$와 격자상수 c-축의 길이는 감소하는 경향을 보였다.을 보였다.$^{zero}$와 격자상수 c-축의 길이는 감소하는 경향을 보였다.