• Journal of Photoscience
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• 제10권2호
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• pp.209-214
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• 2003

A series of coupled-hemicyanine dyes with alkylene spacer were successfully synthesized by a reaction of coupled aldehydes with corresponding salts, respectively. These coupled dyes had more excellent thermal properties (high decomposition temperature, stiff decomposition behavior) and higher molar absorption properties than an uncoupled dye. The coupled dyes with perchlorate anions showed the strongest exothermic decomposition while those with hexafluorophosphorate anions showed endothermic decomposition. As the coupling length (n=3, 4, 5, 6) increased, thermal properties decreased and dyes with even spacer was more thermally stable than dyes with odd spacer. Among several coupled dyes, C4-NP-ClO4 and C4-Cl-ClO4 exhibited the best recording properties with the lowest jitter value of 7.5∼9.5% in authoring disc.

• 폴리머
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• 제33권4호
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• pp.297-306
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• 2009

폴리(비닐 알코올)과 1-{4-(4'-시아노페닐아조)펜옥시}알킬브롬들(CAFBn, n=$2{\sim}10$)을 이용하여 곁사슬형 액정 동족체들인 폴리 [1-(4-(4'-시아노페닐아조)펜옥시알킬옥시)에틸렌]들(CAFETn, n=$2{\sim}10$, 유연격자중의 메틸렌 단위들의 수)을 합성함과 동시에 이들의 열방성 액정 특성을 검토하였다. n=$2{\sim}5$인 CAPBn은 액정 상들을 형성하지 않는 반면 CAPB6 그리고 n=$7{\sim}10$인 CAPBn들은 각각 쌍방성 그리고 단방성 네마틱 상들을 형성 하였다. 이러한 사실과 판이하게, CAPETn 고분자들 중에서 CAPET5만이 쌍방성 네마틱 상을 형성하는 반면 나머지 고분자들은 단방성 네미틱 상들을 형성하였다. CAPETn들의 액체 상에서 네마틱 상으로의 전이온도들 그리고 CAPBn들에 비해 큰 값들을 갖는 CAPETn들의 상 전이시의 엔트로피 변화는 n의 함수로서 전형적인 홀수-짝수 효과를 나타냈다. 이러한 상 전이 거동들을 Imrie에 의한 'virtual trimer model'의 견지에서 검토하였다. CAPETn들의 액정 상의 특성들은 폴리아크릴레이트, 폴리메타크릴레이트 그리고 폴리스티렌에 (시아노페닐아조)펜옥시 그룹들을 플리메틸렌 유연격자들을 통하여 연결시켜 얻은 고분자들에 대해 보고된 결과와 크게 달랐다. 이러한 결과들은 주사슬과 곁사슬 그룹의 화학적 결합양식이 액정 상의 형성능, 안정성 그리고 구조에 중요한 역할을 함을 시사한다.

• 한국대기환경학회지
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• 제13권2호
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• pp.171-174
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• 1997

To provide better insights into the factors and processes regulating the geochemical behavior of airborne lead (Pb), we have investigated several important aspects of its distribution characteristics using the data collected from the Kyung Hee University-Suwon Campus during 1989 through 1994. Although the Pb data in the area reflected the effects of many anthropogenic activities ongoing in the area, the data were quite useful to assess the geochemical facets affecting the temporal distributions of lead as well as particulate matter (PM). The analysis of these data indicated that the Pb patterns were characteristic of enriched Pb levels during odd-numbered years relative to even-numbered years, while those of PM were exhibiting pronouncingly different patterns. Despite many similarities and differences found between year-to-year distribution patterns, of Pb data, it was possible to discuss the facts associated with relatively high concentrations in the years 1991 and 1993 via normalization of Pb against PM data. According to this procedure, we were able to conclude that relative enrichment in Pb levels during 1991 was due to enhanced input of PM, while that of the year 1993 came from more chemically-oriented processes such as active adsorptive scavenging of Pb onto the PM surface. Based on our comparative analysis of the size-fractionated PM and Pb data sets, we propse that two distinctive mechanisms that are both of phyical (1991) and chemical nature (1993) exerted controls over the observed distribution patterns of airborne Pb in the atmosphere of Suwon.

• Asian Pacific Journal of Cancer Prevention
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• 제13권2호
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• pp.437-441
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• 2012

Objective: Health risk appraisal is often utilized to modify individual's health behavior, especially concerning disease prevention, and web-based health risk appraisal services are being provided to the general public in Korea. However, little is known about the psychological effect of the health risk appraisal even though poorly communicated information by the web-based service may result in unintended adverse health outcomes. This study was conducted to explore the psychological effect of health risk appraisal using epidemiological risk factor profile. Methods: We conducted a randomized trial comparing risk factor list type health risk appraisal and risk score type health risk appraisal. We studied 60 women aged 30 years and older who had no cancer. Anxiety level was assessed using the Spielberger State-Trait Anxiety Inventory YZ. Results: The results of multivariate analysis showed that risk status was the independent predictors of increase of state anxiety after health risk appraisal intervention when age, education, health risk appraisal type, numeracy, state anxiety, trait anxiety, and health risk appraisal type by risk status interaction was adjusted. Women who had higher risk status had an odd of having increased anxiety that was about 5 times greater than women who had lower risk status. Conclusions: Our findings indicate that communicating the risk status by individual health risk appraisal service can induce psychological sequelae, especially in women having higher risk status. Hospitals, institutes, or medical schools that are operating or planning to operate the online health risk appraisal service should take side effects such as psychological sequelae into consideration.

• 치위생과학회지
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• 제18권5호
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• pp.305-311
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• 2018

The purpose of this study was to identify the effect of providing toothbrushing by professionals as part of oral hygiene education for the elderly. We randomly visited 12 centers in the metropolitan city and analyzed the data of 114 participants among 310 early registrants aged >65 years, who participated in the study at all 3 time points. The subjects were categorized into an experimental group (odd-numbered visits) and a control group (even-numbered visits). Oral hygiene practices were provided for both experimental and control groups, but professional toothbrushing was performed in a different manner in the experimental group. Differences in plaque index (PI) according to the subjects' general characteristics and oral health status were assessed using the t-test, and the effect of PI difference between the experimental and control groups was assessed by repeated measure two-way analysis of variance. A stepwise multiple regression analysis was used to analyze factors affecting the PI. At baseline, the mean overall PI was 61.82. In both experimental and control groups, the PI significantly reduced from the baseline (p<0.01). At 5 weeks, the experimental group showed a decrease of 27.16 points from the baseline, and the 10-week PI was similar to the 5-week PI. The control group showed a decrease of 14.87 points from the baseline, and the PI increased by 5.74 points at 10 weeks. PI-related factors were gender and self-xerostomia. The PI was lower in the female group and the group with self- xerostomia (p<0.01). It is important to select an appropriate method to educate elderly subjects on proper removal of dental plaque and to habituate correct behavior, which requires inclusion of a direct toothbrushing intervention by a specialist.

• Journal of Preventive Medicine and Public Health
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• 제44권3호
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• pp.118-124
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• 2011

Objectives: Although cigarette smoking is known to be related to the exacerbation of asthma symptoms, several studies have indicated that the prevalence of cigarette smoking among asthmatic adolescents is similar to or even higher than that among non-asthmatic adolescents. The aim of this study was to evaluate the relationship between asthma and cigarette use behaviors and whether or not the presence of suicidal ideation modifies this relationship among Korean adolescents. Methods: We analyzed data from the 2008 Korea Youth Risk Behavior Web-based Survey, which included a nationally representative sample of middle and high school students. Multiple logistic regression models were used to calculate odd ratios and 95% confidence intervals of cigarette use behaviors among current asthmatics, former asthmatics, and nonasthmatics, after adjusting for gender, grade, school records, socioeconomic status, current alcohol use, and suicidal ideation. Results: Of 75 238 study participants, 3.5% were current asthmatics and 4.5% were former asthmatics. Compared with non-asthmatics, asthmatics were more likely to report current cigarette use, frequent and heavy cigarette use, and cigarette use before 13 years of age. There were statistically significant interactions between asthma and suicidal ideation in cigarette use behaviors. Conclusions: This study demonstrated that asthmatic adolescents are more likely than non-asthmatic adolescents to engage in cigarette use behaviors and the presence of suicidal ideation is an effect modifier of the relationship between asthma and cigarette use behaviors. Particular attention should be paid to the awareness of health risks of cigarette smoking and mental health problems among asthmatic adolescents.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.847-853
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• 1999

A Pseudomonas sp. strain that is capable of utilizing dicarboxylic acids as a sole carbon source was isolated from activated sludge by using the enrichment culture technique. This organism accumulated polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units that depends on the carbon sources used. Polyhydroxybutyrate (PHB) homopolyester was synthesized from glucose or small $C_{-even}$ alkanoic acids, such as butyric acid and hexanoic acid. Accumulation of PHB homopolyester was also observed in the cells grown on $C_{-odd}$ dicarboxylic acids, such as heptanedioic acid and nonanedioic acid as the sole carbon sources. In contrast, a copolyester consisting of 6 mol% 3-hydroxybutyrate (3HB) and 94 mol% 3-hydroxyvalerate (3HV) was produced with a PHA content of as much as 36% of the cellular dry matter. This strain produced PHAs consisting both of the short-chain-length (SCL) and the medium-chain-length (MCL) 3-hydroxyacid units when heptanoic acid to undecanoic acid were fed as the sole carbon sources. Most interestingly, polyester consisting of significant amount of relevant fractions, 3HB, 3HV, and 3-hydroxyheptanoate (3HHp), was accumulated from heptanoic acid. According to solvent fractionation experiments, the polymer produced from heptanoic acid was a blend of poly(3HHp) and of a copolyester of 3HB, 3HV, and 3HHp units. The hexane soluble fractions contained only 3HHp units while the hexane-insoluble fractions contained 3HB and 3HV units with a small amount of 3HHp unit. The copolyester was an elastomer with unusual mechanical properties. The maximum elongation ratio of the copolyester was 460% with an ultimate strength of 10 MPa, which was very different from those of poly(3HB-co-3HV) copolyesters having similar compositions produced from other microorganisms.

• 한국수자원학회논문집
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• 제44권6호
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• pp.429-438
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• 2011

In order to simulate a free surface flow in a trench channel, a three-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (RANS) equations are closed with the ${\kappa}-{\epsilon}$ model. The artificial compressibility (AC) method is used. Because the pressure fields can be coupled directly with the velocity fields, the incompressible Navier-Stokes (INS) equations can be solved for the unknown variables such as velocity components and pressure. The governing equations are discretized in a conservation form using a second order accurate finite volume method on non-staggered grids. In order to prevent the oscillatory behavior of computed solutions known as odd-even decoupling, an artificial dissipation using the flux-difference splitting upwind scheme is applied. To enhance the efficiency and robustness of the numerical algorithm, the implicit method of the Beam and Warming method is employed. The treatment of the free surface, so-called interface-tracking method, is proposed using the free surface evolution equation and the kinematic free surface boundary conditions at the free surface instead of the dynamic free surface boundary condition. AC method in this paper can be applied only to the hydrodynamic pressure using the decomposition into hydrostatic pressure and hydrodynamic pressure components. In this study, the boundary-fitted grids are used and advanced each time the free surface moved. The accuracy of our RANS solver is compared with the laboratory experimental and numerical data for a fully turbulent shallow-water trench flow. The algorithm yields practically identical velocity profiles that are in good overall agreement with the laboratory experimental measurement for the turbulent flow.

• 공업화학
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• 제20권6호
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• pp.603-611
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• 2009

펜타-O-4-{4'-(시아노페닐아조)펜옥시}알킬-D-글루코피라노스 동족체들(CAGETn, n = 2~10, 유연격자 중의 메틸렌 단위들의 수)의 열방성 액정 특성을 검토하였다. n = 2, 7인 CAGETn은 쌍방성 네마틱 상들을 형성하는 반면 나머지 유도체들은 단방성 네마틱 상들를 형성하였다. 이것이 글루코오스 유도체가 네마틱 상들을 형성한다고 하는 최초의 보고이다. CAGETns의 액체 상에서 네마틱 상으로의 전이온도들($T_{iNS}$) 그리고 $T_{iN}$에서의 엔트로피 변화는 n의 함수로서 홀수-짝수 효과를 나타냈다. 이러한 거동은 유연격자의 홀수-짝수의 변화에 기인한 곁사슬들의 평균적인 형태변화의 견지에서 합리적으로 설명된다. CAGETns에서 관찰되는 네마틱 상에서 결정 상으로의 전이온도들($T_{NkS}$) 그리고 $T_{Nk}$에서의 엔트로피 변화도 동일한 관점에서 설명된다. $T_{iN}$ 혹은 $T_{Nk}$에서의 엔트로피 변화는 n = 4에서 재차 증가하기 전에 n = 3에서 최소를 나타냈다. 이러한 사실은 곁사슬 그룹들의 배열의 차이에 의해 초래되는 것으로 생각된다. CAGETns의 액정 상의 특성은 글루코오스에 알킬 그룹을 에테르 결합으로 부분적으로 혹은 완전치환시켜 얻은 유도체들에 대해 보고된 결과와 전혀 달랐다. 본 연구결과는 치환기들의 치환도와 화학구조가 액정들의 구조형성에 있어서 중요한 역할을 함을 시사한다.

• 폴리머
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• 제34권2호
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• pp.116-125
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• 2010

복합형 액정 고분자 동족체들인 트리-O-[4-{4'-(시아노페닐아조)페녹시}]알킬셀룰로오스들 (CACETn, n=2-10, 유연격자중의 메틸렌 단위들의 수)의 열방성 액정 거동을 검토하였다. n=5,7인 CACETn은 쌍방성 네마틱 상들을 형성하는 반면 다른 고분자들은 단방성 네마틱 상들을 형성하였다. 액체 상에서 네마틱 상으로의 전이온도($T_{iN}$)는 n이 4까지는 높아지나 n이 5이상에서는 n이 증가함에 따라 낮아졌다. $T_{iN}$에서의 엔트로피 변화도 n=6에서 재차 증가하기 전에 n=5에서 최소치를 나타냈다. n=5에서의 급격한 변화는 곁사슬 그룹들의 배열의 차이에 의해 초래되는 것으로 생각된다. $T_{iN}$들과 달리 네마틱 상에서 결정 상으로의 전이온도들은 현저한 홀수-짝수 효과를 나타냈다. 이러한 사실은 네마틱 상과 결정 상에서의 곁사슬 그룹들의 평균적인 형태가 판이함을 시사한다. CACETn의 액정 특성은 트리-O-알킬 셀룰로오스들 그리고 폴리[1-{4-(4'-시아노페닐아조)페녹시알킬옥시}에틸렌]들에 대해 보고된 결과와 현저히 달랐다. 이러한 결과들을 주사슬과 곁사슬의 화학구조 그리고 반복단위당의 mesogenic 단위들의 차이들의 견지에서 검토하였다.