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Behavior of Steel Fiber-Reinforced Concrete Exterior Connections under Cyclic Loads (반복하중을 받는 강섬유 보강 철근콘크리트 외부 접합부의 거동 특성)

  • Kwon, Woo-Hyun;Kim, Woo-Suk;Kang, Thomas H.K.;Hong, Sung-Gul;Kwak, Yoon-Keun
    • Journal of the Korea Concrete Institute
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    • v.23 no.6
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    • pp.711-722
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    • 2011
  • Beam-column gravity or Intermediate Moment frames subjected to unexpected large displacements are vulnerable when no seismic details are provided, which is typical. Conversely, economic efficiency of those frames is decreased if unnecessary special detailing is applied as the beam and column size becomes quite large and steel congestion is caused by joint transverse reinforcement in beam-column connections. Moderate seismic design is used in Korea for beam-column connections of buildings with structural walls, which are to be destroyed when the unexpected large earthquake occurs. Nonetheless, performance of such beamcolumn connections may be substantially improved by the addition of steel fibers. This study was conducted to investigate the effect of steel fibers in reinforced concrete exterior beam-column connections and possibility for the replacement of some joint transverse reinforcement. Ten half-scale beam-column connections with non-seismic details were tested under cyclic loads with two cycles at each drift up to 19 cycles. Main test parameters used were the volume ratio of steel fibers (0%, 1%, 1.5%) and joint transverse reinforcement amount. The test results show that maximum capacity, energy dissipation capacity, shear strength and bond condition are improved with the application of steel fibers to substitute transverse reinforcement of beam-column connections. Furthermore, several shear strength equations for exterior connections were examined, including the proposed equation for steel fiber-reinforced concrete exterior connections with non-seismic details.

Evaluation of the accuracy of two different surgical guides in dental implantology: stereolithography fabricated vs. positioning device fabricated surgical guides (제작방법에 따른 임플란트 수술 가이드의 정확성비교: stereolithography와 positioning device로 제작한 수술 가이드)

  • Kwon, Chang-Ryeol;Choi, Byung-Ho;Jeong, Seung-Mi;Joo, Sang-Dong
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.4
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    • pp.271-278
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    • 2012
  • Purpose: Recently implant surgical guides were used for accurate and atraumatic operation. In this study, the accuracy of two different types of surgical guides, positioning device fabricated and stereolithography fabricated surgical guides, were evaluated in four different types of tooth loss models. Materials and methods: Surgical guides were fabricated with stereolithography and positioning device respectively. Implants were placed on 40 models using the two different types of surgical guides. The fitness of the surgical guides was evaluated by measuring the gap between the surgical guide and the model. The accuracy of surgical guide was evaluated on a pre- and post-surgical CT image fusion. Results: The gap between the surgical guide and the model was $1.4{\pm}0.3mm$ and $0.4{\pm}0.3mm$ for the stereolithography and positioning device surgical guide, respectively. The stereolithography showed mesiodistal angular deviation of $3.9{\pm}1.6^{\circ}$, buccolingual angular deviation of $2.7{\pm}1.5^{\circ}$ and vertical deviation of $1.9{\pm}0.9mm$, whereas the positioning device showed mesiodistal angular deviation of $0.7{\pm}0.3^{\circ}$, buccolingual angular deviation of $0.3{\pm}0.2^{\circ}$ and vertical deviation of $0.4{\pm}0.2mm$. The differences were statistically significant between the two groups (P<.05). Conclusion: The laboratory fabricated surgical guides using a positioning device allow implant placement more accurately than the stereolithography surgical guides in dental clinic.

The Effect of Rootzone Mix and Compaction on Nitrogen Leaching in Kentucky bluegrass (토양의 종류와 답압이 켄터키블루그래스 토양층에서 질소용탈에 미치는 영향)

  • Lee, Sang-Kook;Frank, Kevin W.;Crum, James R.
    • Asian Journal of Turfgrass Science
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    • v.24 no.1
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    • pp.45-49
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    • 2010
  • Research on nitrate-nitrogen ($NO_3-N$) leaching in turfgrass indicates that in most cases leaching poses minimal risk to the environment. Although there have been many studies investigating $NO_3-N$ leaching, there has been little research to investigate the effect of compaction level and rootzone mix on nitrogen (N) leaching. The research objective is to determine the effect of compaction level and rootzone mix on nitrogen leaching. The four rootzone mixes are 76.0:24.0, 80.8:19.2, 87.0:13.0 and 93.7:6.3 % (sand:soil). The four levels of compaction energies are 1.6, 3.0, 6.1, and 9.1 J $cm^{-2}$. Nitrogen was applied using urea at a rate of 147 kg $ha^{-1}$ split among three applications. Rootzone was packed into a polyvinylchloride pipe with a perforated bottom to facilitate drainage. Rootzone depth was 30 cm over a 5 cm gravel layer. Each column was sodded with Poa pratensis L. Hoagland solution designed for coolseason grasses, minus N, was used to ensure adequate nutrition in the rootzone. Turf grass quality and clipping yield were recorded from each tube at two-week intervals. The clippings were oven-dried at a temperature of $67^{\circ}C$ for 24 h and weighed. At the end of the study, root dry weight was determined by washing and oven-drying samples at $67^{\circ}C$ for 24 h. Leachate solution was collected weekly for analysis. More than 6.1 J $cm^{-2}$ of compaction energy increased possibilities of surface runoff. The compaction energy between 3.0 and 6.1 J $cm^{-2}$ produced more clipping dry weight and less N leaching than 9.1 J $cm^{-2}$.

A Comparative Study on Attitude of the Collegiate an4 Non-Collegiate Nursing Students toward Their Clinical Affiliation in a Mental Hospital (정신과 간호 실습에 대한 간호 대학생과 간호학교 학생들의 태도 비교 연구)

  • 김소야자
    • Journal of Korean Academy of Nursing
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    • v.4 no.2
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    • pp.17-31
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    • 1974
  • Today, over seventy five percent of nursing in Korea provide a psychiatric experience in the basic curriculum. The psychiatric affiliation presents numerous major problems of adjustment to the student. The Importance of positive attitude toward the nursing care of psychiatric patients is recognized by the nursing profession. I have fined out the unfavorable attitude of non collegiate nursing students toward psychiatric nursing affiliation by previous research. This study was undertaken in response to a felt need to explore the use of several devices which might yield information about attitudes toward psychiatric nursing as a basis for future planning of the program offered at a selected hospital. This study is designed to meet the following objectives; (1) In order to find out the expressed attitudes of fifty·three collegiate nursing students toward their psychiatric affiliation. (2) To compare responses given by selected group of collegiate and non collegiate nursing students to same questionnaire (3) To determine the relationship between the attitudes of nursing students toward psychiatric nursing and the type of instructions where experience was obtained. A questionnaire, a Korean translation of the "Psychiatric Nursing Attitude Questionnaire" by Moldered Elizabeth fletcher, was administered to fifty-three collegiate nursing students who had completed a four-week psychiatric affiliation in a S hospital psychiatric ward during May 7, 1973 to Dec. 16, 1973. - The questionnaire of 100 statements was administered in the following way; (1) Part Ⅰ, Preconceptions, was, given in individual conferences with each subject, during the first few days of their affiliation, and again during the final week of affiliation. The responses to Part I were oral. (2) Part Ⅱ, Expectations, Part Ⅲ, Personal Relations, Part Ⅳ, Personal Feelings, and Part V, Attitudes and Activities of Patients were given to all of the subjects in a group meeting during the second week of the affiliation, and again, during the fourth week at the termination of the affiliation. Responses to Parts Ⅱ, Ⅲ, Ⅳ·, and V, were written. Each of the 100 statements of the questionnaire was considered to be either Positive or Negative. A favorable response was assigned the positive value of 1 and an unfavorable response was assigned the Negative value of O. The coefficient of correlation was computed between the two sets of scores for the fifty-three nursing students, The mean score, the standard deviation, and the differences in the means on each of the five parts of the questionnaire were computed and the relationships calculated by at-test. The results of the study were as follows; 1. There was no significant correlation between the two sets of the scores for the fifty-three nursing students during the four-week psychiatric affiliation. (r= 0.36) 2. There was no significant difference in the mean scores between the first and final tests for any of the questionnaire. 3. The Part Ⅰ, Preconceptions, data indicated collegiate nursing students have positive attitudes in preconceptions than non collegiate nursing students and preconceptions toward the psychiatric affiliation which affect their psychiatric nursing experience. 4. The Part Ⅱ, Expectations, data indicated more appropriate expectations of collegiate nursing students related to pre psychiatric affiliation orientation and sufficient theory learning than non-collegiate nursing students. 5. The Part Ⅲ, Personal relations, data indicated some students have negative attitudes in personal relations with normal people in respect to psychological security and social responsibilities. 6. The Part Ⅳ, Personal feelings, data indicated nursing students have psychological insecurity & inappropriateness. 7. The Part V, Attitudes and activities of patients, data indicated collegiate nursing students have more positive attitudes to the psychotic behavior of certain situations due to sufficient theory learning. 8. The data indicated collegiate·nursing students have more positive attitude than non-collegiate nursing students. 5. The Part Ⅲ, Personal relations, data indicated some students have negative attitudes in personal relations with normal people in respect to psychological security and social responsibilities. 6. The Part Ⅳ, Personal feelings, data indicated nursing students have psychological insecurity & inappropriateness. 7. The Part V, Attitudes and activities of patients, data indicated collegiate nursing students have more positive attitudes to the psychotic behavior of certain situations due to sufficient theory learning. 8. The data indicated collegiate·nursing students have more positive attitude than non-collegiate nursing students through psychiatric affiliation.

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The Effects of Emotional Perception on Major Satisfaction among Students at the Department of Dental Hygiene (치위생과 학생의 정서적 인식이 전공만족도에 미치는 영향)

  • Yu, Ji-Su;Choi, Su-Young
    • Journal of dental hygiene science
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    • v.10 no.5
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    • pp.307-314
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    • 2010
  • This study aimed to measure such features of emotional responses perceived by students as learning climate, department living stress, and perceived helplessness to analyze their effects on major satisfaction among students at the department of dental hygiene; to do this, a survey was conducted with 431 students, regardless of college year, who were at the department of dental hygiene in four colleges in Gyeonggi Province, Daejeon, and Chungcheong Province. An existing emotion scale which went through the generalization process was used to draw a multiple model in the combination form in order to collect emotional factors affecting college students' satisfaction with their major, which had existed as a hypothetical proposition, and make overall interpretation of relevance through the explainable, predictable modeling process by measuring emotional factors and phenomenal description of the level of general perception. The results showed that major satisfaction was very significantly affected by emotional features among students at the department of dental hygiene, which needs to be treated as an important factor to enhance expertise related to major learning and improve students' living.

A Studs on Exposure to Organic Dust and Ammonia in Poultry Confinement Buildings (일부 육용 양계 농업인의 유기먼지와 암모니아 노출에 관한 연구)

  • Shin, Cheol-Lim;Lee, Kyung-Suk;Kim, Kyung-Ran;Kang, Tae-Sun;Paik, Nam-Won
    • Journal of agricultural medicine and community health
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    • v.29 no.2
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    • pp.303-314
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    • 2004
  • Objectives: This study was carried out to assess exposure levels of organic dusts and ammonia in poultry farms in Korea. Methods: A total of six poultry farms were investigated. The farms were located in Namwon, Chonlabuk-do and in Kae-San, Chungchongbuk-do. This study consisted of a questionnaire and measuring organic dusts and ammonia. The questionnaire included the characteristics of the farms, work patterns and the tasks of the poultry farms. Results and Conclusions: The farmers raised the chickens 45 times a year and the average number of years in the poultry farm were eight years ranging from 2 to 12 years. They worked for seven days per week and the average hours spent caring the chickens are 6.3 hours per day. The duration of staying in the confinement buildings was 3.3 hours per day. The work time in summer was longest. The feed and the water supply systems were automatic and the control of ventilation windows used "winch curtain" was semiautomatic. They used mechanical ventilation system in winter and used dilution ventilation system in the other seasons. The geometric mean concentration of total and respirable dust sampled in the poultry confinement buildings was 4.0 mg/$m^3$and 0.9 mg/$m^3$ respectively. The ratio of respirable to total dusts range from 9 to 49 percent. There was no sample exceeding the criteria 10 mg/$m^3$ for total dust and 3 mg/$m^3$ for respirable dust in farms. The criteria have been recommended by Korean Ministry of Labor and American Conference of Governmental Industrial Hygienist. The personal respirable dusts measured during a circle work averaged geometric mean concentration 1.4 mg/$m^3$ Two personal samples were exceeded the threshold 3 mg/$m^3$. There was a positive relation between an index and the personal samples of respirable dusts($R^2$=0.98). The index is calculated by multipling the total number of chickens in the farm by the age of the chickens and then dividing by the volume of the confinement building. The geometric mean concentration of area and personal ammonia samples was 23.3 ppm and 22.2 ppm, respectively. Some of the ammonia samples, both area and personal samples, exceeded the short term exposure limit value 35 ppm.

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Fundamental Studies for the Production of Korea Ginseng(Panax ginseng)(II) -Study on the Variations and the Correlations of Important Quantitative characters of Korea Ginseng according to Environmental Conditions (우량인삼생산(優良人蔘生産)을 위(爲)한 육종생리학적(育種生理學的) 연구(硏究)(II) -재식위치(栽植位置)에 따르는 인삼(人蔘)의 주요량적(主要量的) 형질(形質)의 변이(變異)와 그 상호간(相互間)의 관계(關係))

  • Choi, B.Y.;Park, J.S.;Kim, Y.R.;Kim, M.K.;Jo, J.S.;Kim, C.S.
    • Korean Journal of Agricultural Science
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    • v.2 no.1
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    • pp.131-142
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    • 1975
  • This study was carried out to define the variations of important quantitative characters and correlations among them accoding to the planted location under the shadow by planting density. The results obtained are summarized as follows; 1. Growth of leaf and stem of 6 rows and 8 rows planting plots was decreased at front and back rows, but that of root was increased at front row and also decreased at back row. However, at 4 rows planting plots, front row was better for the growth of leaf, stem and root. 2. Average root weight of 6 rows planting plot was 34.29g but that of 8 rows planting plot was ]8.20 g. And total weight of root per unit area was increased and quality of ginseng was better in 6 rows planting plot compaired with 8 rows. 3. Variation by planting locations under the shadow was smallest in stem diameter and highest in root length at 8 row planting plot, but at 6 rows planting plot, that was smallest in leaf blade and greatest in stem length. However, in 4 rows plant ing plot, variation of leaf length was smallest and that of root weight biggest. 4. In all Planting densities, root weight was significantly correlated with root diameter and high correlation was recognized between root diameter and stem diameter. 5. Rate of variations of all characters among plant individuals was different by planting location and that of correlations between quantitative Characters too.

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Fundamental Studies for the Production of Korea Ginseng(Panax ginseng) (I) -Fundamental Study for the Production of the Good Quality Seedlings of Korea Ginseng- (우량인삼생산(優良人蔘生産)을 위(爲)한 육종생리학적(育種生理學的) 연구(硏究) (I) -우량묘삼생산(優良苗蔘生産)을 위(爲)한 기초연구(基礎硏究)-)

  • Choi, B.Y.;Park, J.S.;Kim, Y.R.;Kim, M.K.;Jo, J.S.;Kim, C.S.
    • Korean Journal of Agricultural Science
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    • v.2 no.1
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    • pp.125-130
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    • 1975
  • This investigation was carried out to define the cultivation state of Ginseng seedling and to study the growth of important characters by location and correlations between characters, the results obtained are summarized as follows; 1. Most of farmers culitvating ginseng seedling had not any special consideration for the improvement of soil, and they applied green manure only as basic fertilizer but they did not apply chemical fertilizer. 2. Any efforts on the improvement of ginseng seed were not found. Seed was harvested from 3 years old ginseng plant. Seedling density was 1.8 cm by 2 cm. 3. Growth of all characters showed significant differences among farms. Coefficients of variation among individual seedling plants was largest at root diameter and smallest at root length. 4. Gromth of all characters without root diameter by planted location under the shadow was poor at front row, however root diameter was shortest at back row. 5. Significant high correlatons were rocognized between root diameter and stem diameter, between leaf blade and stem diameter and between leaf blade and leaf length, but stem length were not correlated with any characters. It is noticable that negative correlations were found between stem length and root diameter, between stem length and root length and between stem length and stem diameter.

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A CYANOACETYLENE STUDY OF THE MOLECULAR DISK IN STAR FORMING REGIONS

  • Chung, H.S.;Kameya, Osamu;Morimoto, Masaki
    • Journal of The Korean Astronomical Society
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    • v.24 no.2
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    • pp.217-271
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    • 1991
  • We have observed dense core around young stellar objects, DR21, S140, Orion-KL, and L1551 using four millimeter-wave transitions of $HC_3N\;J$=4-3, J=5-4, J=10-9, and J=12-11. The spatial distribution of $HC_3N$ emission closely resembles the morphology of the previous CS observations that trace high density gas. These observations reveal the existence of $HC_3N$ dense cores around central IR source, elliptical in shape and almost perpendicular to the CO bipolar outflow axis. Small differences can be explained by that $HC_3N$ molecular line is more optically thin and is seen to be more detailed structure in the neighborhood of central IR sources. In S140 and Orion-KL, massive(${\sim}10\;M_{\odot}$), slowly rotating dense cores lie near at the central IR sources of bipolar outflows. The velocity channel maps of DR21 show that the bipolar outflow gas may have a correlation with the dense core of DR21. We analyzed intensities of the four lines to derive physical conditions in dense core from two methods, LTE and LVG. The column density of $HC_3N$, $N(HC_3N)$, between LTE and LVG calculations agree well with each other. The abundances of $HC_3N$ in each observing source have been estimated using the average values of $n(H_2)$ and $N(HC_3N)$ and assuming the size of dense core. The fractional $HC_3N$ abundances in massive dense cores of DR21, S140, and Orion-KL have a range of $(2-7){\times}10^{-10}$, while that of low mass dense core, L1551, has one order of magnitude greater value of $2{\times}10^{-9}$. This should be considered good agreement with the result by Morris et al.(1976). It may be considered that dense cores of DR21, S140, and Orion-KL may have almost same stage of chemical evolution, and their abundances have a small values relative to that of L1551. The column density $N(HC_3N)$ decreases with increasing distance from the densest part of the cloud, the central infrared source, and have the relation of $N(HC_3N){\varpropto}R^{\alpha}$, where a has a range of 0.65 to 0.89. The values of $n(H_2)$ are not varied with increasing distance from the dense core, and have almost same values. Therefore, it is considered that the dense cores in these regions probably consist of dense clumps in diffuse molecular gas medium, and $n(H_2)$ of each clump is ${\sim}10^5\;cm^{-3}$. Levels in the $T_{ex}$ increases with $n(H_2)$. It is considered that the $HC_3N$ dense cores are not completely thermalized. We examine the relationships between the luminosity of central infrared sources versus mass of the dense cores, and the luminosity of central infrared sources versus molecular hydrogen column density. Luminosities of the central IR sources show good correlation with mass and hydrogen column density of the dense core. Same has been found from CS observations. However, mass and size derived from $HC_3N$ observations are one order of magnitude smaller than those from CS. It can be interpreted that we see more central part of the cloud cores in $NC_3N$ lines than CS lines.

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sICAM-1, sE-selectin, sVCAM-1 Concentration in Patients with Pulmonary Tuberculosis (폐결핵 환자에서 SICAM-1, sE-selectin sVCAM-1농도의 변화)

  • Oh, Sang-Mi;Jang, Jae-Ho;Choi, Sang-In;Lee, Heung-Bum;Lee, Yong-Chul;Rhee, Yang-Keun
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.6
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    • pp.1256-1262
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    • 1997
  • Background : Leukocyte-endothelial adhesion molecules have been implicated in the pathogenesis of inflammatory disease. ICAM-1, VCAM-1 and E-selectin are cell surface adhesion molecule on vascular endothelial cells. They are up-regulated by inflammatory cytokines and regulate the adhesion and migration of leukocytes across the endothelium. Tuberculosis, a granulomatous disorder is an infection caused by Mycobacterium tuberculosis. The clinical manifestations of tuberculosis are dependent on the cellular immune response to tubercule bacilli. Circulating adhesion molecules are probably formed by cleavage and release into the circulation of the extracellular domain of the membrane bound form. The elevated levels of circulating adhesion molecules have been reported in numerous disease state. To evaluate their role as markers of disease activity in tuberculosis, we measured a sE-selectin, sVCAM-1 and sICAM-1 levels in the serum with severities of mild, moderate and far advanced pulmonary tuberculosis. Methods : The control and test groups were divided as follows. Group I : control(n=5), Group II : patients with mild pulmonary tuberculosis(n=12), Group III : pateints with moderate pulmonary tuberculosis(n=20), Group IV : patients with far advanced pulmonary tuberculosis(n=19). Serum sICAM-1, sVCAM-1 and sE-selectin were measured by ELISA kit Results : Serum soluble adhesion molecules are elevated in patients with pulmonary tuberculosis, Circulating ICAM-1 levels were significantly elevated in patients with moderate and far advanced pulmonary tuberculosis when compared with control group. When compared with control group, serum sVCAM-1 levels showed significant elevation in patients with mild, moderate and far advanced pulmonary tuberculosis. Serum sE-selectin levels were significantly elevated in patients with far advanced pulmonary tuberculosis when compared with control group. Conclusion : These results suggest that sICAM-1, sVCAM-1, and sE-selectin may be invloved in the pathogenesis of tuberculosis. And, particularly, sICAM-1 and sVCAM-1 may be useful markers of the disease activity.

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