• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1744-1748
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• 2002

Trifluoroacetate anion as a connector has been studied on $AgCF_3CO_2$ with 3,3'-$Py_2X$(X=O vs S) produces 1 : 1 adducts of [Ag($CF_3CO_2$)(3,3'-$Py_2X<$)]. Crystallographic characterization of [Ag($CF_3CO_2$)(3,3'-$Py_2X$)](monoclinic $P2_1$a=7.383(1)$\AA$b=19.801(3)$\AA$c=9.297(3)$\AA$,$\beta$=$100.26(2)^{\circ}$,V=1337.4(5) $\AA^3$, Z=2, R=0.0386) reveals that the 3,3'-$Py_2O$ spacer connects two silver ions to give a single strand and that the single strands are linked via the trifluoroacetate anions in an "up and down even-bridge" to give an elegant molecular grid. The framework of [$Ag(CF_3CO_2)(3,3'-Py_2X)$](monoclinic $P2_1/c$a=8.331(2)$\AA$b=14.010(2)$\AA$,c=11.926(3 $\AA$$\beta$=$93.70(2)^{\circ}$=1385.1(6)$\AA^3$, Z=4, R=0.0589) is a single-strand. The single strands are connected via the trifluoroacetate anions in a double-bridge, resulting in a typical molecular chicken-wire. The trifluoroacetate anion as a connector appears to be primarily associated with its moderately coordinating ability. Their structural features have been discussed based on the anion exchangeability. Thermal analyses indicate that the compounds are stable up to approximately $200^{\circ}C$.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1910-1916
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• 2000

The five classes of the thermally aged CF8M specimen are prepared using an artificially accelerated aging method. Namely, after the specimens are held for 100, 300, 900, 1800, and 3600hrs at 430$^{\circ}C$ respectively, the specimens are water-cooled to room temperature. The impact energy variations are measures for both the aged and virgin specimens through the Charpy impact tests in addition to the microstructure observation, tensile, hardness and fatigue crack growth tests. From the present investigation the following results are obtained : 1) The difference among the thermally degraded specimens can be distinguished through their microstructures, 2) Hardness and tensile strength are increased to 300hrs, degradation specimen, while elongation and reduction area are decreased to 3600hrs degradation specimen, and impact energy is decreased to 1800hrs degradation specimen, 3) The FCG rates for thermally degraded specimens are larger than that of the virgin specimen.

• Journal of Radiation Protection and Research
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• 제11권1호
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• pp.70-76
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• 1986

중성자 측정의 국가표준을 확립하기 위하여 국제원자력거주(IAEA)로 부터 기술지원을 받아서 $MnSO_4$용액조장치를 개발하였다. 본 용액조장치는 구형의 s.s. 316L $MnSO_4$용액조(두께 3.5mm, 내경 125cm), 용액의 순환계 및 5$^{56}Mn\;{\gamma}$-선 검출계동으로 구성되어 있다 .용액조 본체로부터 퍼내어진 용액은 2개의 $3.8cm{\phi}{\times}3.8cm$ NaI(T1) 검출기가 설치된 Marinelli 비이커형의 모니터 용기로 진입되어 순환된다. 본 장치의 성능검사는 $^{241}Am-Be$ 과 $^{252}Cf$ 중성자 선원 을 사용하여 수행하였다. $^{56}Mn$ 방사능의 붕괴 곡선을 분석한 결과, $^{252}Cf$의 중성자 방출율은 1985년 11월 15일 현재 $3.71{\times}10^7\;n/s\;per\;50{mu}g$ 으로 얻어졌다.

• 설비공학논문집
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• 제14권4호
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• pp.332-340
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• 2002

In these days, environmental concerns have been increased throughout the industry and community worldwide. To prevent the ozone depletion, ozone depletion potential of a refrigerant must be zero. Simultaneously, a refrigerant with low GWP (global warming potential) is very demanding to induce green house effect. Chlorine-free HFC-l34a is a refrigerant widely used for automotive air-conditioning system because its destruction potential is ecologically zero. Although HFC-l34a has no ozone depletion potential, its global warming potential is so high that it is not considered as a perfect alternative refrigerant that is acceptable for long-term use. In this paper, experimental measurement has been carried out to analyze the performance characteristics of automotive air-conditioning system using HFC-152a, which has low GWP and zero ODP. Also mixed refrigerant that is composed of HFC-152a and $CF_3$ was applied to investigate an alternative possibility for the automotive airconditioning system. As a result of this study, we could draw following conclusions; With respect to the variation of the rotational speed of compressor, outside air temperature and flow rate, the heat amount of evaporator and compressor and performance coefficient was varied.

• 대한화학회지
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• 제42권3호
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• pp.315-322
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• 1998

새로운 에메소겐 액정화합물들을 합성하였고, 이들의 열적 및 액정 성질을 DSC와 가열판이 부착된 편광현미경을 사용하여 조사하였다. 이 화합물들 즉, 1,10-bis[2,5-bis(4-substitutedphenoxycarbonyl)phenoxy]decane은 "H-자형" 이합체 대칭화합물의 구조로 중앙의 테페프탈로일 단위에 oxydecamethyleneoxy 격자를 통하여 상호 연결된 두 개의 bis(p-substitutedphenoxy)terephthalate 단위로 이루어졌다. 메소겐의 치환기는 X=-F, -H, -I, -Cl, -Br, $-NO_2,\;-CF_3,\;-OC_4H_9-CN$ 및 $-C_6H_5$를 바꾸어 보았다. $X=-OC_4H_9-CN$과 $C_6H_5$ 화합물은 단방성 네마틱액정이었으며 이에 비하여 X=-F, -H, -I, -Cl, -Br, $-NO_2$와 $-CH_3$는 액정이 아니었다. 이 화합물들의 네마틱 그룹 효율은 $-C_6H_5>-CN>-OC_4H_9$ 순이었다.

• 대한약침학회지
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• 제5권1호
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• pp.7-26
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• 2002

Objective: The purpose of this study was to investigate acute and subacute toxicity and sarcoma-180 anti-cancer effects of herbal acupuncture with Carthami- Tinctorii fructus (CF) in mice and rats. Method: Balb/c mice were injected intraperitoneally with Carthami - Tinctorii fructus (CF) for $LD_{50}$ and acute toxicity test. Sprague Dawley rats were injected intraperitoneally with Carthami- Tinctorii fructus (CF) for subacute toxicity test. The Carthami- Tinctorii fructus herbal-acupuncture was injected on Chung-wan (CV12) of mice with Sarcoma-180 cancer cell line. Results: 1. $LD_{50}$ was uncountable as none of the subjects expired during the test. 2. In acute toxicity test, toxic symptoms were not detected, but the body weight of mice was increased in treatment Ⅰ, treatment Ⅱ groups, compared to the normal group.(p<0.05) 3. In acute toxicity test of serum biochemical values of mice, glucose was increased in treatment Ⅰ and treatment Ⅱ groups, total cholesterol was increased in treatment I group, GOT was decreased in treatment Ⅱ group, and GPT was decreased in treatment Ⅰ group, compared to the normal group.(p<0.05) 4. The clinical signs and the body weight of mice treated with 0.1 cc, 0.2cc Carthami- Tinctorii fructus (CF) were not affected during the subacute toxicity test. 5. In subacute toxicity test, treatment groups didn't show significant changes in complete blood count test (CBC) of rats, compared to the nonnal group.(p<0.05) 6. In subacute toxicity test of serum biochemical values of rats, uric acid was decreased in treatment Ⅰ and treatment Ⅱ groups, compared to the nonnal group, triglyceride was decreased in treatment I group, compared to the normal group, GOT and GPT were decreased in treatment I and treatment Ⅱ groups, and alkaline phosphatase was decreased in treatment Ⅰ and treatment Ⅱ groups, compared to the normal group.(p<0.05) 7. Median survival time was increased in all the treatment groups for Sarcoma-180 cancer cell treated with Carthmni- Tinctorii fructus (CF).(p<0.05) 8. Natural killer cell activity was significantly increased in all the treatment groups compared to the normal group.(p<0.05) 9. Interleukin-2 productivity was decreased in treatment Ⅰ and treatment Ⅱ groups.(p<0.05) Conclusion: According to the results, we can conclude herbal-acupuncture of Carthami-Tinctoriifructus (CF) caused negligible toxkity, and had anti-tumor effects in mice.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권1호
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• pp.1-12
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• 2022

Inflammation plays an important role in the outcome of patients with cystic fibrosis (CF). It may develop due to cystic fibrosis transmembrane conductance regulator protein dysfunction, pancreatic insufficiency, or prolonged pulmonary infection. Fecal calprotectin (FC) has been used as a noninvasive method to detect inflammation. Therefore, the aim of the current meta-analysis was to investigate the relationship between FC and phenotype severity in patients with CF. In this study, searches were conducted in PubMed, Science Direct, Scopus, and Embase databases up to August 2021 using terms such as "cystic fibrosis," "intestine," "calprotectin," and "inflammation." Only articles published in English and human studies were selected. The primary outcome was the level of FC in patients with CF. The secondary outcome was the relationship between FC and clinical severity. Statistical analysis was performed using Comprehensive Meta-Analysis software. Of the initial 303 references, only six articles met the inclusion criteria. The mean (95% confidence interval [CI]) level of FC was 256.5 mg/dL (114.1-398.9). FC levels were significantly associated with pancreatic insufficiency (mean, 243.02; 95% CI, 74.3 to 411.6; p=0.005; I²=0), pulmonary function (r=-0.39; 95% CI, -0.58 to -0.15; p=0.002; I²=60%), body mass index (r=-0.514; 95% CI, 0.26 to 0.69; p<0.001; I²=0%), and Pseudomonas colonization (mean, 174.77; 95% CI, 12.5 to 337.02; p=0.035; I²=71%). While FC is a reliable noninvasive marker for detecting gastrointestinal inflammation, it is also correlated with the severity of the disease in patients with CF.

• 한국결정학회지
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• 제11권1호
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• pp.28-33
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• 2000

The slow of 2,3-bis(2-pyridyl)pyarzine(bpp) with Ag(CF₃CO₂) produces crystalline product suitable for X-ray crystallography. Crystallographic characterization of the crystal (C/sub 32/H/sub 20/-F/sub 6/N/sub 8/O₄Ag₂: triclinic P1, a=8.518(5)Å, b=9.546(2)Å, c=10.632(1)Å, α=81.11(1)°, β=87.61(3)°, γ=75.66(3)°, V=827.5(5)ų, Z=1, R=0.0431) has provided that the complex is a cyclic dimer [Ag(bpp)(CF₃CO₂)]₂. Each bpp ligand connects two tetrahedral silver(I) ions in a tridentate mode (Ag-N, 2.26()-2.43(2)Å), and the trifluoroacetato anion is bonded to each silver(I) atom in a monodentate fashion (Ag-O, 2.38(1); 2.39(2) Å). The skeletal cyclic dimer is stable up to 212℃, and drastically decomposes around this temperature.

• Macromolecular Research
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• 제12권2호
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• 대한수학회지
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• 제31권4호
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• pp.659-667
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• 1994

Let $H$ be a separable, infinite dimensional, complex Hilbert space and let $L(H)$ be the algebra of all bounded linear operators on $H$. A dual algebra is a subalgebra of $L(H)$ that contains the identity operator $I_H$ and is closed in the ultraweak operator topology on $L(H)$. Note that the ultraweak operator topology coincides with the weak topology on $L(H) (cf. [6]). Several functional analysists have studied the problem of solving systems of simultaneous equations in the predual of a dual algebra (cf. [3]). This theory is applied to the study of invariant subspaces and dilation theory, which are deeply related to the classes $A_{m,n}$ (that will be defined below) (cf. [3]). An abstract geometric criterion for dual algebras with property $(A_{\aleph_0}, {\aleph_0})$ was first given in [1].