• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.585-589
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• 2008

Second-order rate constants (kN) have been measured for reactions of Y-substituted phenyl 2-thiophenecarboxylates (6a-h) with morpholine and piperidine in 80 mol % H2O/20 mol % DMSO at 25.0 0.1 oC. The Brnsted-type plot for the reactions of 6a-h with morpholine is linear with b lg = 1.29, indicating that the reactions proceed through a tetrahedral zwitterionic intermediate (T?). On the other hand, the Brnsted-type plot for the reactions of 6a-h with piperidine exhibits a downward curvature, implying that a change in the rate-determining step occurs on changing the substituent Y in the leaving group. Dissection of kN into microscopic rate constants (i.e., k1 and k2/k1 ratio) has revealed that k1 is smaller for the reactions of 6a-h than for those of Y-substituted phenyl 2-furoates (5a-h), while the k2/k1 ratio is almost the same for the reactions of 5a-h and 6a-h. It is also reported that modification of the nonleaving group from the furoyl (5a-h) to the thiophenecarbonyl (6a-h) does not influence pKao (defined as the pKa at the center of the Brnsted curvature) as well as the k2/k1 ratio.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.344-351
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• 1987

Kinetic studies on the complexing of $[Mo_2O_4(H_2O)_6]^{2+}$ with thiocyanate have been carried out using the spectrophotometric method. The observed rate constant is given by, $k_{obsd}=\{\\k_0+k_H[H^+]\}\;[SCN^-]^2+k_r$. At $25^{\circ}C$ and ionic strength of 2.84 the values of $k_f\;and\;k_r\;are\;5.96{\pm}0.35\;M^{-2}s^{-1}\;and\;(5.45{\pm}4.77){\times}10^{-4}s^{-1}$, respectively. Activation parameters from data at $20^{\circ}$∼$35^{\circ}C\;are\;{\Delta}H^*=38.04{\pm}5.31kJmol^{-1}\;and\;{\Delta}S^*=-172.69JK^{-1}mol^{-1}$. The mechanisms are discussed.

• Bulletin of the Korean Mathematical Society
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• v.53 no.3
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• pp.885-902
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• 2016

In this paper we begin the study of $L_k$-2-type hypersurfaces of a hypersphere ${\mathbb{S}}^{n+1}{\subset}{\mathbb{R}}^{n+2}$ for $k{\geq}1$ Let ${\psi}:M^3{\rightarrow}{\mathbb{S}}^4$ be an orientable $H_k$-hypersurface, which is not an open portion of a hypersphere. Then $M^3$ is of $L_k$-2-type if and only if $M^3$ is a Clifford tori ${\mathbb{S}}^1(r_1){\times}{\mathbb{S}}^2(r_2)$, $r^2_1+r^2_2=1$, for appropriate radii, or a tube $T^r(V^2)$ of appropriate constant radius r around the Veronese embedding of the real projective plane ${\mathbb{R}}P^2({\sqrt{3}})$.

• Journal of Energy Engineering
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• v.4 no.1
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• pp.67-75
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• 1995

50 kW 냉방용 화학열펌프에 관한 전산설계를 하기 위하여 반응기 모사용 부프로그램을 작성하였으며 전체 시스템을 위하여 상용모사기인 ASPEN PLUS를 이용하였다. 반응물로 각각 SrCl2-8/1 NH3 그리고 MnCl2-6/2 NH3를 사용하는 두 시스템에 대하여 비교 연구하였으며, 조작조건에 따라 시스템 설계치의 변화를 관찰하였다. 이로부터 향후 실용화될 화학열펌프 시스템에 대한 기본 설계자료를 제시할 수 있었다. SrCl2-8/1 NH3를 반응물로 한 경우 반응기의 UA는 6,868.2 J/(s·K), 출력은 95.2 kW이었고, 제한 성능 계수는 0.40이었다. MnCl2-6/2 NH3의 경우 UA는 1,569.7 J/(s·K), 출력은 109.0 kW이었으며 제한 성능계수는 0.34이었다. 이로부터 SrCl2-8/1 NH3을 반응물로 한 시스템이 MnCl2-6/2 NH3를 사용한 시스템보다 유리함을 알 수 있었다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.121-130
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• 2022

This study was conducted to determine the suitable amount of irrigation and fertigation for the growth and yield of spring potatoes (Solanum tuberosum L.). To investigate the effect of soil moisture content on the growth and yield of potato, five irrigation treatments were performed based on soil moisture tension: -10 kPa, -20 kPa, -30 kPa, -40 kPa, and non-irrigation. The growth and yield among the irrigation treatments was the best in the -10 kPa treatment, where the yield increased by 47% compared to the non-irrigation treatment. To determine the standard of additional fertilizer for fertigation cultivation of spring potatoes, seven treatments were performed, including a control (basic fertilization without additional fertilizer), compound fertilizer (NPK) based on 0.5 times the standard amount of fertilizer (NPK 0.5; N-P₂O₅-K₂O: 2.5-2.2-3.25 kg/10a), NPK 0.8 (N-P₂O₅-K₂O: 4-3.5-5 kg/10a), and NPK 1.2 (N-P₂O₅-K₂O: 6-5.3-7.8 kg/10a), and potassium fertilizer of 2 kg (K 2), 5 kg (K 5), and 7 kg (K 7). The growth and yield among the fertilization treatments was highest in the K 5 treatment, where the yield increased by approximately 27% compared to the control. Therefore, this study suggests that irrigation with -10 kPa or fertigation with K 5 during the tuber initiation and tuber filling stage could increase the yield of spring potatoes.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.334-343
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• 1987

The Chemical reactions between $NiL_m{^{2+}}\{$Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}$}\and\ CN^-$ ion were studied by the spectrophotometric method. The equilibrium constants (K_1$) for the 1:1 complex ion, $[NiL_m(CN)]^+\;with\;NiL_m{^{2+}}\;and\;CN^-$ ion were determined in the range of 3 to $25^{\circ}C$. The $K_1\;for\;Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;at\;15^{\circ}C$ was 4.7, 5.3, 6.2, 7.5, 9.4, and 9.8, respectively. The values of $K_1$ decreased with increasing temperature. From the temperature effect on equilibrium constant ($K_1$), thermodynamic parameters $({\Delta}H^{\circ},\;{\Delta}S^{\circ},\;{\Delta}G^{\circ})$ for reaction were evaluated and the reaction of $NiL_m{^{2+}}\;and\;CN^-$ ion was exothermic. $NiL_m{^{2+}\;reacts\;with\;CN^-$ ion to give $Ni(CN)_4{^{2-}}$ ion and macrocyclic ligand $(L_m)$. The kinetics of formation of the $Ni(CN)_4{^{2-}}$ ion of varying the $[CN^-],\;[HCN],\;and\;[OH^-]$ have been investigated at 3∼$25^{\circ}C\;and\;0.5M\;NaClO_4$. Maintaining a constant $[CN^-],\;k_{obs}/[CN^-]^2$ increases linearly with increasing [HCN]. In the presence of large quantities of $[OH^-],\;k_{obs}/[CN^-]^2$ also increases linearly with $[OH^-]$. From the temperature effect on kinetic constant (k_{obs})$, parameter of activation $({\Delta}H^{\neq},\;{\Delta}S^{\neq})$ of reaction of $NiL_m{^{2+}}\;with\;CN^-$ ion were determined. For the $Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;series\;{\Delta}H^{\neq}$ gradually decrease as the d-d transition energy, $ν(cm^{-1})$ decrease. And the reaction of the five $NiL_m{^{2+}}\;with\;CN^-$ ion take place by way of equal paths.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.505-513
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• 2008

The two-step thermochemical cycle was examined on the $CeO_2$, YSZ, and $ZrO_2$-supported $NiFe_2O_4$ to investigate the effects of support material addition. The supported $NiFe_2O_4$ was prepared by the aerial oxidation method. Thermal reduction was conducted at 1573K and 1523K while water-splitting was carried out at 1073K. Supporting $NiFe_2O_4$ on $CeO_2$, YSZ and $ZrO_2$ alleviated the high-temperature sintering of iron-oxide. As a result, the supported $NiFe_2O_4$ exhibited greater reactivity and repeatability in the water-splitting cycle as compared to the unsupported $NiFe_2O_4$. Especially, $ZrO_2$-supported $NiFe_2O_4$ showed better sintering inhibition effect than other supporting materials, but hydrogen production amount was decreased as cycle repeated. In case of $CeO_2$-supported $NiFe_2O_4$, improvement of hydrogen production was found when the thermal reduction was conducted at 1573K. It was deduced that redox reaction of $CeO_2$ activated above 1573K.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.137-146
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• 1992

The adsorption properties of CO on the cation exchanged natural zeolite, $K_{111}$ and cation effects upon the CO adsorption were studied. $Na^+-,\;Cu^{2+}-\;and\;Ba^{2+}-\;K_{111}$ exhibited relatively good CO adsorption capacities and $Ba^{2+}- K_{111}$ treated by 0.4 N-$BaCl_2$ solution proved itself as the best adsorbent and superior to the synthetic zeolite 4A and 5A. The observed adsorption tendency due to the cations were in the order of $Ba^{2+}>Cu^{2+}>Na^+>K^+>Mg^{2+}>Ca^{2+}$. The cation exchanged number per unit cell as well as the kind of cation which forms bond with CO molecules in different intensities and other mineral factors such as pore size indicated to be important factors to the CO adsorption properties. The CNDO/2 calculations were performed to compare the adsorption tendencies and CO interaction energy of cations in $K_{111}$.

• YAKHAK HOEJI
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• v.51 no.5
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• pp.313-317
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• 2007

A series of luotonin A homologues and their aza-analogues were prepared and evaluated their inhibitory activities on COX-1 and 2 as well as their selectivities on COX-2. The aza-analogue of dimethylene-bridged homologue of luotonin A, 3,3'-dimethylene-2-(1',8'-naphthyrid-2'-yl)-4(3H)-quinazolinone (2b), exhibited strongest inhibitory activity against COX-1 and COX-2 dependent phase of prostaglandin $D_2$ generation in mouse bone marrow-derived mast cells in a concentration-dependent manner with an $IC_{50}$ of 39.3 and $1.89{\mu}M$, respectively. Selectivity of 2b on COX-2 over COX-1 was 21 which implied 2b can be a potential lead for the development of selective COX-2 inhibitor.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.325-328
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• 2003

본 논문에서는 주어진 손님 그래프 모델의 정점들과 간선들을 성능 파라미터들을 보다 우수하게 유지하면서 주인 그래프의 대응되는 정점들 및 경로들로 매핑시키는 "그래프 임베딩 문제"라고 불리는 그래프이론 문제를 다룬다. 높이가 N인 피라미드 모델을 손님 그래프로 하여 0$(4^{(k+1)}+2)/3{\times}2^{(N-k-1)}{\times}2^{(N-k-2)}$ 구조의 병렬컴퓨터 모델로 임베딩할 수 있는 새로운 매핑 함수를 제안하고 해당 함수 적용시 신장율이 $max\{(2^{(2k+1)}+4)/3,\;5{\cdot}2^{N-k-2}/8\}$로 개선됨을 증명함으로써 그 성능을 분석한다.