• Korean Journal of Mathematics
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• 제25권3호
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• pp.437-453
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• 2017

A new class of sets, called generalized (${\Lambda}$, b)-closed sets, has been introduced and studied. Also, several properties of generalized (${\Lambda}$, b)-closed sets are investigated. Some characterizations of ${\Lambda}_b$-regular spaces and ${\Lambda}_b$-normal spaces are discussed.

• 한국전기전자재료학회논문지
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• 제19권1호
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• pp.29-34
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• 2006

The effects of $B_2O_3$ addition on the low-temperature sintering behavior and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$ ceramic system were investigated. Highly dense samples were obtained at the sintering temperatures below $900^{\circ}C$. The $Q{\times}f_o$ values were determined by the microstructures and sintering shrinkages which are affected by the amount of $B_2O_3$ and sintering temperature. Temperature coefficient of resonance frequency($T_f$) changes to a positive value with increasing the amount of $B_2O_3$ due to the increased amount of rutile phase which is one of the reaction products between $(Zn_{0.8}Mg_{0.2})TiO_3$ and $B_2O_3$. For $6.19 moi.{\%}B_2O_3$-added $(Zn_{0.8}Mg_{0.2})TiO_3$ system, it exhibits ${\epsilon}_r$ = 23.5, $Q{\times}f_o$ = 53,000 GHz, and $T_f$ = 0 ppm/$^{\circ}C$ when sintered at $900^{\circ}C$ for 5 h.

• 한국환경보건학회지
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• 제23권4호
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• pp.91-96
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• 1997

In order to investigate the behavior of particulate carbon and benzo(a)pyrene(B(a)P) in the ambient air, suspended particle matters were collected from April, 1990 to February, 1992, and total carbon(TC), organic carbon(OC), elemental carbon(EC) and B(a)P were measured by an elemental analyzer and a HPLC. The results were as follows the average concentration of TC was 38.6 $\mug/m^3$ and its concentration was higher in winter(45.4 $\mug/m^3$) and fa11(44.3 $\mug/m^3$) than in summer(36.8 $\mug/m^3$) and spring(28.9 $\mug/m^3$). The monthly concentration trends both of EC and OC was similar, but seasonal variation of EC concentrations was larger than that of OC. The average concentration of B (a)P was 2.2 ng/m$^3$, and was higher in winter(4.1 ng/m$^3$) and fall(3.2 ng/m$^3$) than in spring(1.2 ng/m$^3$) and summer(0.6 ng/m$^3$). The seasonal behavior of carbon and B(a)P was to similar except for summer. The correlation coefficient(r) between EC and B(a)P was 0.71, and the correlation coefficient(r) between OC and B(a)P was 0.66.

• Journal of Ecology and Environment
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• 제35권4호
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• pp.313-322
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• 2012

A 2-year study (2010-2011) was carried out in order to evaluate the effects of bean and maize intercropping. The experiment tested five different cropping systems: sole cropping of each crop, as well as intercropping of maize/bean with the ratios of 1:3 ($M_1B_3$), 2:2 ($M_2B_2$) and 3:1 ($M_3B_1$), each of which took place in the presence of two weed management systems (no weed control and weed eradication through manual removal), in a factorial experiment based on randomized complete block design using three replicates. Tests of homogeneity of variance for combined data over two years showed that data of both years could be analyzed together. The results showed that the effect of intercropping treatments on all measured traits in maize and bean were significantly different. A minimum land equivalent ratio (LER) for maize (0.78) was obtained for $M_3B_1$ under conditions of no weed control, while the highest LER (1.03) was observed in $M_3B_1$ under weed-free conditions. The highest (0.99) and lowest (0.70) LER values for beans were recorded for $M_1B_3$ under weed-free conditions and $M_3B_1$ under conditions of no weed control, respectively. $M_1B_3$ under weed-free conditions showed the highest total LER (2.02), while $M_3B_1$ under conditions of no weed control showed the lowest (1.48). Results of this study indicated that intercropping bean and maize can be an effective method to increase total productivity, and that the $M_1B_3$ system was the best cropping system for high productivity.

• Archives of Pharmacal Research
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• 제21권4호
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• pp.465-469
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• 1998

The search for platinum (II)-based compounds with improved therapeutic properties was prompted to design and synthesize a new family of water-soluble, third generation cis-diaminedichloroplatinum (II) complexes linked to uracil and uridine. Six heretofore unreported uracil and uridine-platinum (II) complexes are; [N-(uracil-5-yl-methyl)ethane-1,2-di-amine]dichloroplatinum (II) (3a), [N-(uracil-6-yl-methyl)ethane-1,2-diaminel dichloroplatinum (II) (3b), t[N-($2^1$, $3^1$,$5^1$-tri-O-acetyl)uridine-5-yl-methyl] ethane-1,2-diamineldichloroplatinum (II) (6a), {[N-($2^1$,$3^1$, $5^1$-tri-O-acetyl) uridine-6-yl-methyl]ethane-1,2-diamine)dichloroplatinum (II) (6b),[N-(uridine- 5-yl-methyl)ethane-1,2-diamine]dichloroplatinum (II) (7a), [N-(uridine-6-yl- methyl)ethane-1,2-diamine]dichloroplatinum (II) (7b). These analogues were prepared from the key starting materials, 5-chloromethyluracil (1a) and 6-chloromethyluracil (1b) which were reacted with ethylenediamine to afford the respective 5-[(2-aminoethyl)aminol methyluracil (2a) and 6-[(2-aminoethyl)amino]methyluracil (2b). The cis-platin complexes 3a and 3b were obtained through the reaction of the respective 2a and 2b with potassium tetrachloroplatinate (II). The heterocyclic nucleic acid bases 1a and 1b were efficiently introduced on the .betha.-D-ribose ring via a Vorbruggen-type nucleoside coupling procedure with hexamethyldisilazane, trimethylchlorosilane and stannic chloride under anhydrous acetonitrile to yield the stereospecific .betha.-anomeric 5-chloromethyl- $2^1$,$3^1$,$5^1$-tri-O-acetyluridine (4a) and 6-chloromethyl-$2^1$,$3^1$,$5^1$-tri-O-acetyluridine (4b), respectively. The nucleosides 4a and 4b were coupled with ethylenediamine to provide the respective 5-[(amino-ethyl)aminolmethyl-$2^1$,$3^1$,$5^1$-tri-O-acetyluridine (5a) and 6-[(aminoethyl)amino] methyl-$2^1$,$3^1$,$5^1$-tri-O-acetyluridine (5b). The diamino-uridines 5a and 5b were reacted with potassium tetrachloroplatinate (II) to give the novel nucleoside complexes, 6a and 6b, respectively which were deacetylated into the free nucleosides, 7a and 7b by the treatment with CH$_{3}$ONa. The cytotoxic activities were evaluated against three cell lines (FM-3A, P-388 and J-82) and none of the synthesized compounds showed any significant activity.

• Journal of Gastric Cancer
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• 제19권3호
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• pp.329-343
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• 2019

Purpose: Gastric cancer with lymph node metastasis (LNM) more than 15 (N3b) was defined as stage IV until the 6th AJCC system. However, it has been reclassified as a localized disease (stage IIb or III) since the 7th system. The aim of this study is to demonstrate that the survival of N3b is comparable to cytology-only positive (CY1-only) stage IV and to propose a new TNM system interpreting N3b as an eligibility criterion for receiving more intensive chemotherapy regimens. Materials and Methods: 1,430 patients who underwent gastric cancer surgery at Seoul National University Hospital from 2007 to 2012 were retrospectively analyzed. The 5-year survival rate (5YSR) and 3-year recurrence-free survival (RFS) were evaluated according to the 7th and 8th systems, as well as a new categorization based on N-classification; N0-2 (LNM<7), N3a (LNM 7-15), or N3b (LNM>15). Results: The survival of N3b is comparable to that of CY1-only stage IV (log rank test, P=0.671) and is distinct from that of grossly stage IV (log rank test, P<0.001). The survival of the remaining stage IIIc (T4bN3a) was comparable to those of N3b and CY1-only stage IV. Most N3b patients had significantly shorter 3-year RFS and mean RFS than those with IIb-IIIc, as if N3b itself was a higher TNM stage. Conclusions: In terms of survival, T4bN3a, N3b, and CY1-only stage IV were unified as stage IVa, while grossly stage IV was defined as stage IVb. N3b can be regarded as an eligibility criterion for undergoing more intensive chemotherapy regimens.

• 한국재료학회지
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• 제15권11호
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• pp.735-740
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• 2005

The phase transformation of Ni-B diffusion barrier by Cu diffusion was studied. The Ni-B diffusion barrier, thickness of 10(Inn, was electrolessly deposited on the electroplated Cu interconnect. The specimens were annealed either in Ar atmosphere or in $H_2$ atmosphere from $300^{\circ}C\;to\;800^{\circ}C$ for 30min, respectively. Although the Ni-B coated specimens showed the decomposition of $Ni_3B$ above $400^{\circ}C$ in both Ar atmosphere and $H_2$ atmosphere, Ni-B powders did not show the decomposition of $Ni_3B$. The $Ni_3B$ was decomposed to Ni and B in hi atmospherr: and the metallic Ni formed the solid solution with Cu and the free B was oxidized to $B_2O_3$. However, both the boron hydride and free B were not observed in the diffusion barrier after the annealing in $H_2$ atmos There. These results revealed that the decomposition of $Ni_3B$ by Cu made the Cu diffusion continued toward the Ni-B diffusion barrier.

• 대한화학회지
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• 제38권12호
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• pp.908-914
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• 1994

5원자 고리형 ${\beta}$-keto ester와 phenylalkylamine의 탈수축합으로 얻은 enamine A의 oxalyl화 및 물이나 메탄올 부가에 의하여 octahydro-2,3-dioxo-cyclopenta[b]-pyrrole-3a-carboxylate의 6a-hydroxy- 및 6a-methoxy-유도체(1~6)를 합성하였다. 헤테로 고리의 형성은 불안정한 N-acyliminium(B)체를 경유하여 일어나며, 안정한 부가체 C (1∼6)는 endo-ene형 pyrrolinium B에 친핵체를 부가하여 얻을 수 있었다.

• 한국컴퓨터산업학회논문지
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• 제10권4호
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• pp.135-142
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• 2009

본 논문에서는 주파수도약용 통신시스템을 위한 40~60[MHz]의 주파수 범위를 갖는 트래킹 필터를 설계, 제작하였다. 트래킹필터의 성능결과 삽입손실은 각 호핑 중심주파수에서 3.7~4.3[dB], 3[dB]대역폭은 중심주파수에서 5.1~5.33[%], 필터의 차단특성인 30/3[dB] shape factor는 6.828~6.98로 설계목표를 만족하고 있음을 알 수 있다. 하지만 $2{\times}f_0$의 감쇄량은 46~52[dB]가 측정되어 설계목표에 미치지 못하고 있음을 알 수 있다.

• 대한전자공학회논문지SD
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• 제40권8호
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• pp.549-554
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• 2003

본 논문에서 단거리전용통신을 위한 차량탑재장치내의 수신단 전반부의 구성부품인 5.8GHz대역 LNA를 MMIC로 설계 및 구현하였다. 설계된 LNA는 두개의 능동소자와 매칭회로, 두개의 드레인 바이어스 회로로 구성되며, 3V의 단일공급전압에서 18mA의 소비전류로 동작한다. 중심주파수 5.8GHz에서 이득 13.4dB, NF 1.94dB, Input IP3-3dBm, S/sub 11/ - l8dB, S/sub 22/ - 13.3dB의 특성을 나타내며, 제작된 회로의 실제 크기는 1.2×0.7㎟ 이다.