• 설비공학논문집
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• 제4권2호
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• pp.123-136
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• 1992

A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.237-240
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• 2001

• Journal of Advanced Marine Engineering and Technology
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• 제16권4호
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• pp.78-87
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• 1992

The experimental study and theoretical analysis are made in order to investigate a new refrigeration system, R-22 and R-502 or R-13 cascade compressor with panel type cooler, for tuna long liner. The experimental apparatus consists with the cascade unit, 1.5 HP R-502 compressor in the first stage and 1 HP R-22 compressor in the second stage, and 3 $m^2$ cold storage room with a direct expansion panel type cooler. The main result are as follows: 1. The energy saving and C.O.P. of the R-22 and R-502 or R-22 and R-13 cascade are improved much higher than two stage compressor. 2. For the point of simplicity of design, installation, and running cost, the panel type cooler is much better than traditional hair pin coil type cooler. 3. From the experimental data and analysis, the R-22 and R-502, or R-22 and R-13 cascade compressor with panel type cooler is recommended for a new refrigeration equipment of the tuna long liner.

• 대한수학회지
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• 제32권2호
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• pp.289-300
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• 1995

Every group G has a unique maximal normal locally nilpotent subgroup $\Phi(G)$, called the Hirsh-Plotkin radical of G [9]. If G is a group, we define the upper Hirsh-Plotkin series of G to be the ascending series $1 = R_0 \leq R_1 \leq \ldots$ in which $R_{\alpha+1}/R_\alpha = \{Phi(G/R_\alpha)$ for each ordinal $\alpha and R_\beta = \cup_{\alpha<\beta}R_\alpha$ for each limit ordinal $\beta$. If $R_r = G$ for some natural number r, then G is said to have locally nilpotent length r. $(LN)^r$ denotes the calss of groups of locally nilpotent length at most r.

• 대한수학회보
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• 제60권2호
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• pp.339-348
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• 2023

It is shown that every nilpotent-invariant module can be decomposed into a direct sum of a quasi-injective module and a square-free module that are relatively injective and orthogonal. This paper is also concerned with rings satisfying every cyclic right R-module is nilpotent-invariant. We prove that R ≅ R₁ × R₂, where R₁, R₂ are rings which satisfy R₁ is a semi-simple Artinian ring and R₂ is square-free as a right R₂-module and all idempotents of R₂ is central. The paper concludes with a structure theorem for cyclic nilpotent-invariant right R-modules. Such a module is shown to have isomorphic simple modules eR and fR, where e, f are orthogonal primitive idempotents such that eRf ≠ 0.

• Applied Biological Chemistry
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• 제28권3호
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• pp.149-155
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• 1985

전국(全國) 223개(個) 지역(地域)에서 수집(蒐集)한 두과작물(豆科作物)의 근류(根瘤)에서 총(總) 590주(株)의 근류균(根瘤菌)을 분리(分離)하여 숙주특이성(宿主特異性)에 따라, R. japonicum 218종(種), R. phaseoli 101종(種), R. trifolii 97종(種), R. meliloti 4종(種), R. leguminosarum 1종(種), Rhizobium species 101종(種), 미분류(未分類)된 균주(菌株) 159종(種)으로 분류(分類)하였다. 분리(分離)된 R. japonicum 218종(種)의 근류형성능(根瘤形成能)과 질소고정능(窒素固定能)을 비교(比較)하여. R. japonicum R-138, R-168, R-214 균주(菌株)를 우수균주(優秀菌株)로 하였다. 분리(分離) 선발(選拔)된 R. japonicum 중(中) 질소고정능(窒素固定能)이 우수(優秀)한 균주(菌株)의 plasmid를 확인(確認)한 결과(結果), fast-growing group 균주(菌株)들은 $1{\sim}4$개(個)의 거대(巨大) plasmid를 함유(含有)하고 있었으며 그 분자량(分子量)은 약(約) $35{\sim}300{\;}Md$ 정도(程度)이었다. 반면 대부분(大部分)의 slow-growing group 균주(菌株)들은 plasmid가 검출(檢出)되지 않았다.

• 대한화장품학회지
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• 제41권2호
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• pp.143-150
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• 2015

본 연구는 3,7-diarylpyrazolo [1,5-${\alpha}$]pyrimidines의 효과적인 one-pot regioselective 합성을 보여준다. 더욱이, 그 유도체는 뛰어난 CB1R 저해 활성을 나타냈다. 3,7-position에 diaryl group이 치환된 pyrazolo [1,5-${\alpha}$]pyrimidine은 CB1R 후보로서 가능성 있는 pharmacophore이다.

• 충청수학회지
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• 제28권1호
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• pp.139-143
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• 2015

In this paper, we prove that (r, s)-semi-irresolute image of the (r, s)-semi-${\theta}$-connected set is also (r, s)-semi-${\theta}$-connected. Moreover, we prove that an (r, s)-semi-irresolute mapping preserves (r; s)-$S^*$-closedness.

• 대한화학회지
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• 제41권3호
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• pp.150-156
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• 1997

Bulgecinine의 선구물질인 (4S,5R)-1-acetyl-2-formyl-5-benzyloxymethyl-4-pyrrolidinol (15)을 diacetone-D-glucose로부터 합성하였다. Barton 탈산소화 반응, C-5에서의 반전, $-N_3$ 도입과 환원 및 C-2에서의 고리 형성을 통해 bulgecinine의 핵심 중간체인 두 고리 화합물 (6R)-6-Ο-benzyloxymethyl-(3R)-3-methoxy-2-oxa-5-azabicyclo-[2,2,1]heptane (13)을 합성하였다. 화합물 13을 N-아세틸화 후 산가수분해하여 얻은 bulgecinine 선구물질은 토토머화가 수반되어 (2S,4S,5R)-pyrrolidinol 유도체 15와 함께 (2S,4S,5R)-부분 입체 이성질체도 얻어졌다.

• 한국컴퓨터정보학회논문지
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• 제24권7호
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• pp.61-69
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• 2019

In this paper, a classification method of random graph models is proposed and it is based on centralities of the random graphs. Similarity between two random graphs is measured for the classification of random graph models. The similarity between two random graph models $G^{R_1}$ and $G^{R_2}$ is defined by the distance of $G^{R_1}$ and $G^{R_2}$, where $G^{R_2}$ is a set of random graph $G^{R_2}=\{G_1^{R_2},...,G_p^{R_2}\}$ that have the same number of nodes and edges as random graph $G^{R_1}$. The distance($G^{R_1},G^{R_2}$) is obtained by comparing centralities of $G^{R_1}$ and $G^{R_2}$. Through the computational experiments, we show that it is possible to compare random graph models regardless of the number of vertices or edges of the random graphs. Also, it is possible to identify and classify the properties of the random graph models by measuring and comparing similarities between random graph models.