• 대한기계학회논문집B
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• 제25권1호
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• pp.71-77
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• 2001

A flow visualization study using the oil film method and the smoke-laser light sheet arrangement is carried out to investigate the three-dimensional flow pattern around the free end surface region of a finite circular cylinder (aspect ratios of 1.25 and 4.25) mounted on a flat plate. The experiment is performed for the cases of two Reynolds numbers: 5.92${\times}$10$^3$and 1.48${\times}$10(sup)5. Various kinds of singular points on the free-end surface are disclosed from the oil surface flow visualization. The smoke-laser light sheet visualization, to aid in understanding the oil streak-line patterns, clearly demonstrates that a pair of tornado-like vortices marched along the downstream together with a pair of side tip vortices. A topological sketch to characterize the surface flow and the four vortices emanating from the top surface is included.

• 한국전산유체공학회지
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• 제14권3호
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• pp.115-122
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• 2009

Numerical methods are applied to simulate the smoke behavior in a ventilated tunnel using large eddy simulation (LES) which is incorporated in FDS (Fire Dynamics Simulator) with proper combustion and radiation model. In this study, present numerical results are compared with data obtained from experiments on pool fires in a ventilated tunnel. The model tunnel is $182m(L){\times}5.4m(W){\times}2.4m(H)$. Two fire scenarios with different ventilation rates are considered with two different fire strengths. The present results are analyzed with those from LES without combustion and radiation model and from RANS ($\kappa-\epsilon$) model as well. Temperature distributions caused by fire in tunnel are compared with each other. It is found that thermal stratification and smoke back-layer can be predicted by FDS and the temperature predictions by FDS show better results than LES without combustion and radiation model. The FDS solver, however, failed to predict correct flow pattern when the high ventilation rate is considered in tunnel because of the defects in the tunnel-inlet turbulence and the near-wall turbulence.

• 한국보건간호학회지
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• 제19권2호
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• pp.305-315
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• 2005

Purpose: The purpose of this study was to investigate the relationships among depression, sleep patterns and health promoting behavior in female college students. Methods: The subjects of this study consisted of 350 college students. The data was collected through self-administered questionnaires from November to December of 2004. The data was analyzed via the SPSS computer program by using descriptive statistics, t-tests, ANOVA and Pearson's correlation coefficients. Results: There are significant differences and impacts on depression according to the amount of coffee consumed, the time spent on computer and the amount of smoke inhaled. Sleep patterns differ depending on one's college major, the time spent on computer, and the amount of smoke inhaled. Health promotion behavior was shown to be significantly different according to the living style, college major and how much TV was watched The mean scores for depression, sleep patterns, health promoting behavior were 1.45 (on a 3 points scale), 2.71 (on a 4 points scale), and 3.03 (on a 5 point scale), respectively. There was a significant positive correlation between sleep patterns and health promoting behavior, and there was negative correlation between depression and health promoting behavior, and between depression and sleep patterns in college students. Conclusion: The findings of this study give useful information to create further studies on intervention programs related to health promoting behavior for college female students.

• 한국환경보건학회지
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• 제28권1호
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• pp.11-20
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• 2002

Tobacco smoke was confirmed as a human carcinogen by many research results. Because many adolescents stay long time in the PC game room, they are exposed to much of tobacco smoke. To evaluate the effect of passive smoking in the PC game room, airborne nicotine concentrations in 2 PC game rooms in Sung-nam city and urinary cotinine concentrations were measured for 20 adolescents. And the subjects were interviewed for duration and time in PC game room and smoking pattern. Subjects are composed of each of 10 smokers(5 males and 5 females) and 10 nonsmokers(5 males and 5 females). They stayed for three hours in the PC game room without smoking. Concentrations of nicotine in smokers and nonsmokers were 129.72 $\mu$g/$^3$ and 99.99 $\mu$g/m$^3$, respectively. Urinary cotinine concentrations were increased as time goes on after exposure to nicotine and showed maximum value at 9.45 hours after nicotine exposure and were 32.21 and 110.66 $\mu$g/L for nonsmoker and smokers. The more using time and frequency in PC game room, the higher urinary cotinine maximum concentration and the longer using duration, also the more increase urinary cotinine concentration. Urinary cotinine has a tendency to increase by passive smoking. Therefore, it is recommended that the effective control for indoor air quality and extensive research be needed to reduce nicotine concentration by passive smoking in the PC game room.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1586-1591
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• 2004

Flow visualization experiments have been performed to investigate the effects of phase lag, reduced frequency qualitatively by examining wake pattern on a dragonfly type wing. The model was built with a scaled-up, flapping wings, composed of paired wings with fore- and hindwing in tandem, that mimicked the wing form of a dragonfly. The present study was conducted by using the smoke-wire technique, and an electronic device was mounted to find the exact positional angle of wing below the tandem wings, which amplitude is ranged from $-16.5^{\circ}$ to $+22.8^{\circ}$. Phase lag applied on the wings is $0^{\circ}$, $90^{\circ}$, $180^{\circ}$ and $270^{\circ}$. The reduced frequency is 0.15, 0.3 and 0.45 to investigate the effect of reduced frequency. It is inferred through observed wake pattern that the phase lag clearly plays an important role in the wake structures and in the flight efficiency as changing the interaction of wings. The reduced frequency also is closely related to wake pattern and determines flight efficiency.

• 한국연초학회지
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• 제27권1호
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• pp.83-93
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• 2005

This study was conducted to evaluate the effect of additives in low sidestream cigarette papers, such as Mg$(OH)__2,\;TiO_2\;and\;KH_{2}PO_4$ on the delivery of mainstream and sidestream smoke. From the analysis of tar and nicotine in sidestream and mainstream smoke, the delivered ratios of tar and nicotine by sidestream to mainstream smoke in common cigarette paper were 5.32 and 8.60, respectively. However, the delivered ratios of those of the paper containing $Mg(OH)_2\;were\;2.25\~3.23,\;4.86\~7.14,\;Mg(OH)_2\;and\;KH_{2}PO_4\;were\;2.12\~2.92,\;4.67\~6.89,\;TiO_2\;was\;3.21,\;7.51 $ respectively. The deliver patterns of semi-volatile components in the cigarettes were similar each there, but a slight different pattern in the amount was observed depending on the kinds of compounds added in cigarette papers. In the cigarettes made of $Mg(OH)_2$ added paper, the aromatic components such as benzene, toluene and phenol were generated more while the aliphatic components like neophytadiene, ethyl decanoate were delivered less than the cigarettes made of common cigarette papers. However, the cigarettes manufactured with $Mg(OH)_2\;and\;KH_2PO_4$ added paper showed an opposite trend. The cigarettes made of $TiO_2$ added paper showed relatively low delivery in the most compounds measured. In sensory evaluation, cigarette papers tested were noticed a distinguishable sensory character between the low sidestream smokes with additive cigarette papers except $TiO_2$ added one. Moreover, aroma patterns detected by a electronic nose system in TPM were a similar tendency.

• 생명과학회지
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• 제18권11호
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• pp.1543-1550
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• 2008

실내 환경 오염원으로 각종 암 발병과 관련이 있는 흡연이 피부 피지샘의 glycoconjugates에 미치는 영향을 lectin 조직화학으로 연구하였다. Sprague-Dawley계 수컷 흰쥐에 1일 1회 10분간 1일군, 2일군, 3일군 및 5일군으로 나누어 직?간접 흡연 방법으로 폭로시켜 피지샘 형태는 PAS 염색, 피지샘의 glycoconjugates 양상을 9종의 biotinylated lectin (DBA, SBA, PNA, BSL-1, WGA, RCA-1, UEA-1, Con A 및 LCA)으로 연구하였다. 대조군에 비해 흡연군에서는 피지샘꽈리의 크기 감소, 피지샘꽈리 상부의 파괴, 중앙부 피지세포의 공포화 및 미성숙 피지샘꽈리가 관찰되었다. 대조군에서 피지샘 glycoconjugates에는 염색성에 차이가 있으나 기저세포는 BSL-1, PNA 및 WGA에만 반응하고 BSL-1의 반응이 더 강하며, 피지세포는 PNA, WGA, Con A, BSL-1 및 SBA에만 반응하고 PNA 및 Con A의 반응이 더 강했다. 흡연군의 렉틴 반응에서 특이적인 변화가 관찰되었다. 흡연군의 피지샘 기저세포의 PNA 반응은 증가되었고, BSL-1는 감소되었다가 회복되었으며, WGA는 소실되었다. 피지세포의 Con A는 증가하였으나 PNA, BSL-1, WGA 및 SBA는 감소 또는 소실되었다. 대조군에 관찰되지 않던 흡연군의 미성숙 샘꽈리 PNA, on A 및 BSL-1이 반응하였으며 PNA 및 Con A의 반응이 더 현저하였다. 결론적으로 흡연은 피지샘의 형태 및 glycoconjugates 대사에 심한 영향을 미치는 것으로 사료된다.

• 한국터널지하공간학회 논문집
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• 제8권4호
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• pp.325-334
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• 2006

시계조절이나 설해방지 목적으로 설치되는 캐노피 구간 내에서의 기류유동특성의 이해는 정상환기 뿐만 아니라 비상시 대처방안 강구를 위한 요건이다. 또한 터널 방재시스템 설계를 위하여서는 종단구배, 평면선형, 단면크기 및 형태 등과 같은 터널의 다양한 특성이 화재확산에 미치는 영향에 대한 정량적인 이해가 필요하다. 본 연구에서는 국내도로터널의 전형적인 특성을 적용한 터널에 캐노피가 된 경우와 종단 및 선형구배, 단면적 및 형태, 곡선구간이 환기 및 화재확산에 미치는 영향을 CFD분석함을 목적으로 하였다. 분석결과 145m길이의 캐노피인 경우 50%정도의 개구율이 기류유동 패턴 및 환기효과면에서 가장 바람직하였다. 1.8km 터널내에서 20MW 화재발생시 종단구배는 풍속분포와 화재연 확산에 큰 영향을 미치며 제트팬$({\varnothing}1250)$ 4대를 가동한 경우 화재발생 후 5분 경과시 하류 40m지점 부근에서의 화재연 농도는 +2% 구배에서는 13% 감소, -2% 구배의 경우에는 20%정도 증가하며 또한 backlayering거리가 45m정도에 달한다. 직사각형 단면터널의 경우, 화재연 농도 및 풍속분포는 말굽형 터널과 비교하여 현저한 차이가 관찰되지 않는다. 3차선 터널에서는 이들 변수는 모두 감소하며 100초 경과시 50m 정도의 backlayering을 보이며 이후 서서히 감소한다. 곡선터널인 경우는 화재연의 확산이 느리며 100초 경과시 50m에 달하던 backlayering현상은 급격히 사라진다.

• International Journal of Costume and Fashion
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• 제5권2호
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• pp.55-67
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• 2005

The purpose of this study is to document an unidentified velvet fabric which is located in the Museum. The investigation was conducted by analyzing color, weaving technique. pattern of the study object. To identify the origin of the object, many references about color trends, construction methods and patterns were accessed. Two comparative objects which were dating from 1600 to 1699 in the Museum of F.I.T. were selected since they are similar to the study object. The results of this study can be summarized as follows; (1) The type of this study object is 'cut and voided velvet'. It is obtained establishing the motif as areas of cut pile so as to form a pattern, while leaving other areas of the grounded weave without pile. Two flowers and two tulips with S curved stems are composed as one unit in the vertical direction. (2) The colors used in this study object. which are ivory, smoke blue, medium orange, and yellow. are part of a new trend color in the $17^{th}$ century. (3) The vertical undulating stripe patterns are also of significance in this fabric. They seemed to be contemporary with the serpentine line which was common since the $15^{th}$ century and the vertical stripes pattern which appeared from the $16^{th}$ century. (4) The stylized tulip patterns of this study object began to appear in the early $17^{th}$ century. The stems and leaves of this patterns are less sinuous than the floral motifs of the later $17^{th}$ century. Therefore, the study object is dated to early in $17^{th}$ century because of the color combination. stripes. stylized tulips, leaves. and stems are showing the characteristics of this period.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.736-744
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• 2003

This study is conducted to investigate aerodynamic forces and wake structures about the pressure interference of a circular cylinder with slits. An experimental investigation of a circular cylinder with slits is carried out in uniform flow in the range of Reynolds number from 8,000 to 32,000 using X-type hot wire. Flow visualization is executed by smoke-wire method to understand the mechanism of these vortex formation process. Inspection in the wake at X/D=5.5 of the cylinder with the slits suggested that a strong vortex-shedding pattern for these cylinders is revealed compare with a circular cylinder without slits. It is found that the rolling up position of shear layer of the cylinder with slits is shorten compare with a circular cylinder without slits.