• Title/Summary/Keyword: 연구 경향성

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Community Ecological Study on the Quercus acuta Forests in Bogildo-Island (보길도(甫吉島) 붉가시나무림(林)의 군락생태학적(群落生態學的) 연구(硏究))

  • Kim, Chong-Young;Lee, Jeong-Seok;Oh, Kwang-In;Jang, Seok-Ki;Park, Jin-Hong
    • Journal of Korean Society of Forest Science
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    • v.89 no.5
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    • pp.618-629
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    • 2000
  • This study was carried out to investigate ecological niche of Quercus acuta communities in Bogildo-island from July to October, 1998. This island is occupied by a subtropical evergreen broad-leaved forests. The study on community ecology of Q. acuta, mostly dominant species of subtropical forests, is very important for successful forest management. Sampling areas were selected in 16 quadrats, dominated by Q. acuta to examine the vegetation characteristics(plant identification, D.B.H.) and environmental elements (microtopography, altitude, slope degree, aspect, illumination and soil physicochemical properties). On the basis of data from field surveys, importance values were calculated for the dominance of Q. acuta and volume growth was analyzed by tree ring widths. The results obtained were as follows ; 1. The lists of vascular plants in the investigations were identified as 54 families, 91 genera, 113 species, 9 varieties, 1 formae. It appeared that 45 kinds were evergreen, 6 kinds(Camellia japonica, Ligustrum japonicum, Eurya japonica, Smilax china, Trachelospermum asiaticum var. intermedium, Carex lanceolata) were commonly observed in all plots and 5 species(Cinnamomum japonicum, Ardisia japonica, Cymbidium goeringii, Dryopteris bissetiana, Viburnum erosum) were most highly observed in all plots(over 80%). 2. The dominating species per strata were, Quercus acuta, Castanopsis cuspidata sp. Quercus salicina, Pinus thunbergii, Prunus sargentii in tree layer, Camellia Japonica, Ligustrum japonicum, Quercus acuta, Eurya japonica, Castanopsis cuspidata sp. in subtree layer, Camellia japonica, Ligustrum japonicum, Smilax china, Cinnamomum japonicum, Viburnum erosum in shrub layer and Trachelospermum asiaticum var. intermedium, Ardisia japonica, Carex lanceolata, Camellia japonica(seedlings), Quercus acuta(seedlings) in herb layer, all in descending orders. 3. Quercus acuta could be suggested as shade intolerant tree, considering the distribution in southern, western, nothern and eastern slopes in the descending orders. 4. Mean relative illumination in the forest is 0.89 % and it is relatively low in brightness. 5. Sustainment of Quercus acuta community couldn't be confirmed by judging from their reverse J curve in even-aged forest, as shown in D.B.H. distribution analysis. 6. The result of annual ring width analysis(mean ; 2.44 mm) showed three stages, such as a gentle increasing(1~12 year ; 2.04 mm), a relatively steep increasing(13~22 year ; 2.95 mm) and decreasing or stagnating(23 year after ; 2.41 mm).

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Nitrogen Removal Rate of A Subsurface Flow Treatment Wetland System Constructed on Floodplain During Its Initial Operating Stage (하천고수부지 수질정화 여과습지의 초기운영단계 질소제거)

  • Yang, Hong-Mo
    • Korean Journal of Environmental Agriculture
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    • v.22 no.4
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    • pp.278-283
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    • 2003
  • This study was carried out to examine the nitrogen removal rate of a subsurface-flow treatment wetland system which was constructed on floodplain of the Kwangju River from May to June 2001. Its dimensions were 29m in length, 9m in width and 0.65m in depth. A bottom layer of 45cm in depth was filled with crushed granite with about $15{\sim}30\;mm$ in diameter and a middle layer of 10cm in depth had pea pebbles with about 10 mm in diameter. An upper layer of 5 cm in depth contained course sand. Reeds (Phragmites australis) were transplanted on the surface of the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju River flowed into it via a pipe by gravity flow and its effluent was funneled back into the river. The height of reed stems was 44.2 cm in July 2001 and 75.3cm in September 2001. The number of stems was increased from $80\;stems/m^2$ in July 2001 to $136\;stems/m^2$ in September 2001. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged 40.0 and $39.2\;m^3/day$, respectively. Hydraulic detention time was about 1.5 days. Average nitrogen uptake by reeds was $69.31\;N\;mg/m^2/day$. Removal rate of $NO_3-N$, $NH_3-N$, T-N averaged 195.58, 53.65, and $628.44\;mg/m^2/day$, respectively. Changes of $NO_3-N$ and $NH_3-N$ abatement rates were closely related to those of wetland temperatures. The lower removal rate of nitrogen species compared with that of subsurface-flow wetlands operating in North America could be attributed to the initial stage of the system and inclusion of two cold months into the six-month monitoring period. Increase of standing density of reeds within a few years will develop both root zones suitable for the nitrification of ammonia and surface layer substrates beneficial to the denitrification of nitrates into nitrogen gases, which may lead to increment in the nitrogen retention rate.

Effect of rbST Administrations at Artificial Insemination on Conception and Parturition Rates in Hanwoo (한우 인공수정시 rbST 투여가 수태 및 분만율에 미치는 영향)

  • Han M. H.;Choi S. H.;Choi Y. H.;Kim H. J.;Cho S. R.;Choi C.Y.;Ryu I. S.;Son D. S.;Yeon S. H.;Woo J. S.;Kweon U. G.;Yoon K. Y.;Chang B. S.
    • Journal of Embryo Transfer
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    • v.20 no.2
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    • pp.177-184
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    • 2005
  • This study was conducted to investigate the effects of recombinant bovine somatotropin (rbST) injection on conception and parturition rates in normal or repeat breeding Hanwoo. We treated 462 cows containing 79 repeat-breeding cows of multiparous and allocating 5 treatment groups. Treatment 1 (T1) was injection of 2ml saline (for pseudo treatment), T2 was one injection of rbST 250mg into the tailhead region at the estrus, T3 was twice injection of rbST 250mg both at the time of insemination and again 10 to 14 day later, T4 was once injection of rbST 500mg at insemination and T5 was twice injection of 500mg rbST both at the time of insemination and again 10 to 14day later respectively. In rbST treated groups, timed artificial inseminations (TAI) were performed fellowing estrus synchronization. 100 us GnRH was injected into the scapula region on Day 0, 25mg $PGF_2{\alpha}$ was injected on Day 7 for degeneration of corpus luteum (CL) and 100ug GnRH was injected for inducing the synchronization. The results are as fellows; When normal Hanwoo were inseminated once with rbST administration, the pregnancy rate of T2 $(67.5\pm18.48\%)$ were higher than control $(52.4\pm9.72\%)$, while the pregnancy rate of T4 $(63.3\pm5.77\%)$ were significantly higher (p.<0.05) than control $(39.3\pm12.89\%)$ in repeat breeder Hanwoo. The parturition rates of normal Hanwoo were no differences among the treatments but were significant different in repeat breeder Hanwoo (p<0.05). When the estrous was induced by Ovsynch and inseminated once with rbST administration, the pregnancy rates of T2 was $12.5\%$ higher than control in normal Hanwoo, T4 $(80.0\%)$ was highest among the treatments (p<0.05) in repeat breeder Hanwoo. When normal Hanwoo were inseminated once with rbST administration, the pregnant period was $282.7\~284.8$ days and the body weight was $25.1\~25.9kg$, there were no difference among the treatments. The ratio of sex was almost same without T4 (male vs. female=18:9). In repeat breeder Hanwoo, pregnant period was 280.4~289.3 day and body weight was $23.0\~26.6kg$, it had no difference among the treatments. The sex ratio were similar to normal Hanwoo except T4 (M : F=2 : 8). In conclusion, the pregnancy and parturition rate by once insemination could be improved by the administration of rbST 250mg in normal Hanwoo or 500mg in repeat breeder Hawoo.

Lymphocyte Proportion and Cytokines from the Bone Marrow of Patients with Far-Advanced Pulmonary Tuberculosis with Peripheral Lymphocytopenia (말초혈액의 림프구감소증을 동반한 중증폐결핵 환자들에서 골수 내의 림프구 분획과 사이토카인 소견)

  • An, Chang Hyeok;Kyung, Sun Yong;Lim, Young Hee;Park, Gye Young;Park, Jung Woong;Jeong, Sung Hwan;Ahn, Jeong Yeal
    • Tuberculosis and Respiratory Diseases
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    • v.55 no.5
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    • pp.449-458
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    • 2003
  • Background : The poor prognostic factors of far-advanced pulmonary tuberculosis(FAPTB) are lymphocytopenia in the peripheral blood(PB)(< $1,000/mm^3$) and $T_4$-cell count ${\leq}500/mm^3$. However, the cause of PB lymphocytopenia in FAPTB is unclear. The aim of this study was to analyze the lymphocyte proportion and cytokines of the bone marrow(BM) in FAPTB patients with peripheral lymphocytopenia in order to clarify whether the limiting step of the lymphocytopenia occurs in production, differentiation, or circulation. Methods : This study included patients with FAPTB between August 1999 and August 2002 who visited Gachon Medical School Gil Medical Center. The exclusion criteria were old age(${\geq}65years$), cachexia or a low body weight, shock, hematologic diseases, or BM involvement of tuberculosis. The distributions of cells in PB and BM were analyzed and compared to the control group. The interleukin(IL)-2, IL-7, IL-10, TNF-${\alpha}$, Interferon-${\gamma}$, and TGF-${\beta}$ levels in the BM were measured by ELISA. Result : Thirteen patients(male : female=9:4) were included and the mean age was $42{\pm}12$years. The proportion and count of the lymphocytes in the PB were significantly lower in the FAPTB group ($7.4{\pm}3.0%$, $694{\pm}255/mm^3$ vs. $17.5{\pm}5.8%$, $1,377{\pm}436/mm^3$, each p=0.0001 and 0.002). The proportion of immature lymphocyte in the BM showed a decreasing trend in the FAPTB group($9{\pm}4%$ vs. $12{\pm}3%$, p=0.138). The IL-2($26.0{\pm}29.1$ vs. $112.2{\pm}42.4pg/mL$, p=0.001) and IL-10($3.4{\pm}4.7$ vs. $12.0{\pm}8.0pg/mL$, p=0.031) levels in the BM were significantly lower in the FAPTB group than those in control. The levels of the other cytokines in FAPTB group and control were similar. Conclusion : These results suggest that the cause of lymphocytopenia in PB is associated with a abnormality IL-2 and IL-10 production in the BM. More study will be needed to define the mechanism of a decreased reservoir in BM.

Studies on the Improvement of Nursery for Better Ripening Percentage and Prevention of Red Discoloration of Rice Variety "Tongil" (통일벼의 등숙(登熟) 향상(向上)과 적고방지(赤枯防止)를 위(爲)한 묘대개선(苗垈改善)에 관(關)한 연구(硏究))

  • Choi, Boum Rawl
    • Korean Journal of Agricultural Science
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    • v.1 no.1
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    • pp.9-26
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    • 1974
  • 1. Results in Nursery This experiment was carried out on the effect of the seed treament, soil preparations, kinds of covering soil and inside covering methods in two rice varieties, 'Tongil' and 'Akibare' to find out the most reasonable model of the flat nursery bed, with which lower cost is required comparing with the tunnel nursery. The results obtained are as follows: (1) The seedling of all plots of the ordinary seed were very poor compared to the plots of sprouted seed. (2) In case that the variety 'Tongil' was cultivated on the dry nursery bed, the good seedling percentage and the plant height rat io were significantly increased but the other characteristics of the seedling were not noticeable. (3) The kinds of the covering soil had not an effect on the seedling growth significantly. (4) Inside straw mulching was seemed effective for the protection in the case of the extreme high temperature and heavy rain fall, even though there was not significant differences between inside straw mulching and no treatments at the flat type nursery. (5) Difference of seedling growth between the flat type nursery and the tunnel type nursery was not significant. And it's reason was thought that the covering period of polyethylene film was short in semi hot nursery for the common early transplanting cultivation of rice. (6) The percentage of good seedling was higher at 'Akibare' than 'Tongil', variety but the number of seedling leaf and the seedling growth ratio in height were significantly increased in the variety 'Tongil'. The other seedling characters between there two varieties were not significantly different. 2. Results after transplanting This experiment was conducted to study on the ripening percentage, rice yield and disease, appearance of the seedling from sprouted seed plots including common irrigated nursery as check plot after transplantnig. The results obtained are summarized as follows: (1) The rice yield, the yield components and the appearance of leaf discoloration of both varieties, 'Tongil' and 'Akibare' were slightly betterat the plot of the standard tunnel nursery than that of the flat nursery with inside mulching or the among these three plots. (2) For 'Tongil' variety, the ripening percentage and the rice yield were significantly decreased at the common irrigated nursery compared with semi hot nursery. (3) The ripening percentage and the rice yield of 'Akibare' contrasted with 'Tongil' were significantly decreased at thesemi 'hot-nursery compared with common irrigated nursery. The main reason was thought to be the injury of the rice stripe disease (Rice stripe disease virus). Considering above mentioned experimental result, the seedling of 'Tongil' must be cultivated on the semi bot nursery for better ripening percentage as well as rice yield and for prevention of red discoloration. And as a model of semi hot nursery, the polyethylene covering nursery of standard tunnel type is most desirable but that of flat type with inside straw mulching is thought to be desirable too.

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Clinical Study of Pulmonary Tuberculosis for Admitted Patients at National Masan Tuberculosis Hospital (국립마산결핵병원에 입원한 환자에 대한 폐결핵의 임상적 동태에 관한 연구)

  • Park, Seung-Kyu;Choi, In-Hwan;Kim, Chul-Min;Kim, Cheon-Tae;Song, Sun-Dae
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.2
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    • pp.241-250
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    • 1997
  • Objective : Although the prevalence of pulmonary tuberculosis has decreased progressively after the national control program for tuberculosis began, nowadays the number of MDRTB is increasing seriously. MDRTB tends to be poor responsive to current antituberculosis regimens. It is mainly due to poor compliance, high rate of side reaction of secondary drugs, and limitation in number of available drugs. The purpose of present study is to evaluate the clinical features of pulmonary tuberculosis patients admitted in one national tuberculosis hospital and to expose the problems pertaining to current remedies, to increase the treatment efficacy for pulmonary tuberculosis including MDRTB in the end. Method : Retrospective analysis of 336 pulmonary tuberculosis patients admitted in National Masan Tuberculosis Hospital was done. Contents of analysis were patients profile, the first diagnosed time and medical institutes, family history, residence, previous treatment history, chief complaints at the time of admission, lesion site on chest X -ray film, combined deseases, side reaction to antibuberculosis drugs, used drugs before admission and the results of drug sensitivity test. Results : The ratio between male and female was 4 : 1. Age showed relatively even distribution from 3rd to 6 th decades. 64.6% of the patients was diagnosed at public health center. Weight loss was the most common complaint at admission. Bilateral lesions on chest X-ray films were 59.8%. 130patients had combined desease, of which DM was the most common(37.7%). 95patients had family history, of which parents were the most common(41.7%). According to the time of first diagnosis, 31 patients were diagnosed before 1980, and after then the number of patients was increased by degrees. Residence overwhelmed in pusan and gyung-nam province. 258 patients got previous treatment history, of which 112 patients(43.4%) had more than 3 times and only 133 patients(51.6%)got regular medication. 97 patients used more than other 3 drugs in addition to INH, EMB, RFP and PZA before admission. 154 patients were informed with the results of drug sensitivity test. of which 77 patients had resistance to more than 5 drugs. Gastrointestinal problem was the most common in side reaction to drugs. Conclusion : In the case of weight loss of unknown cause, tuberculosis should be suspected. In first treatment, sufficient and satisfactory explanation for tuberculosis is necessary and treatment period should not be stict to 6 month-short term therapy. In retreatment, new drugs should not be added to used drugs even though drug sensitivity results show sensitivity to some of them. Proper time for surgical intervention should not be delayed.

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Effects of Molecular Weight of Polyethylene Glycol on the Dimensional Stabilization of Wood (Polyethylene Glycol의 분자량(分子量)이 목재(木材)의 치수 안정화(安定化)에 미치는 영향(影響))

  • Cheon, Cheol;Oh, Joung Soo
    • Journal of Korean Society of Forest Science
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    • v.71 no.1
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    • pp.14-21
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    • 1985
  • This study was carried out in order to prevent the devaluation of wood itself and wood products causing by anisotropy, hygroscopicity, shrinkage and swelling - properties that wood itself only have, in order to improve utility of wood, by emphasizing the natural beautiful figures of wood, to develop the dimensional stabilization techniques of wood with PEG that it is a cheap, non-toxic and the impregnation treatment is not difficult, on the effects of PEG molecular weights (200, 400, 600, 1000, 1500, 2000, 4000, 6000) and species (Pinus densiflora S. et Z., Larix leptolepis Gordon., Cryptomeria japonica D. Don., Cornus controversa Hemsl., Quercus variabilis Blume., Prunus sargentii Rehder.). The results were as follows; 1) PEG loading showed the maximum value (137.22%, Pinus densiflora, in PEG 400), the others showed that relatively slow decrease. The lower specific gravity, the more polymer loading. 2) Bulking coefficient didn't particularly show the correlation with specific gravity, for the most part, indicated the maximum values in PEG 600, except that the bulking coefficient of Quercus variabilis distributed between the range of 12-18% in PEG 400-2000. In general, the bulking coefficient of hardwood was higher than that of softwood. 3) Although there was more or less an exception according to species, volumetric swelling reduction was the greatest in PEG 400. That is, its value of Cryptomeria japonica was the greatest value with 95.0%, the others indicated more than 80% except for Prunus sargentii, while volumetric swelling reduction was decreased less than 70% as the molecular weight increase more than 1000. 4) The relative effectiveness of hardwood with high specific gravity was outstandingly higher than softwood. In general, the relative effectiveness of low molecular weight PEG was superior to those of high molecular weight PEG except that Quercus variabilis showed more than 1.6 to the total molecular weight range, while it was no significant difference as the molecular weight increase more than 4000. 5) According to the analysis of the results mentioned above, the dimensional stabilization of hardwood was more effective than softwood. Although volumetric swelling reduction was the greatest at a molecular weight of 400. In the view of polymer loading, bulking coefficiency reduction of swelling and relative effectiveness, it is desirable to use the mixture of PEG of molecular weight in the range of 200-1500. To practical use, it is recommended to study about the effects on the mixed ratio on the bulking coefficient, reduction of swelling and relative effectiveness.

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A Study on the Liturgical Vestments of Catholic-With reference to the Liturgical Vestments Firm of Paderborn and kevelaer in Germany (카톨릭교 전례복에 관한 연구-독일 Paderborn 과 kevelaer의 전례복 회사를 중심으로)

  • Yang, Ri-Na
    • The Journal of Natural Sciences
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    • v.7
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    • pp.133-162
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    • 1995
  • Paderborn's companies, Wameling and Cassau, produce the liturgical vestments, which have much traditional artistic merit. And Kevelaerer Fahnen + Paramenten GmbH, located in Kevelater which is a place of pilgrimage of the Virgin Mary, was known to Europe, Africa, America and the Scandinavia Peninsula as the "Hidden Company" of liturgical vesments maker up to now. Paderborn and Kevelaer were the place of the center of the religious world and the Catholic ceremony during a good few centries. The Catholic liturgical vestiments of these 3 companies use versatile design, color, shape and techniques. These have not only the symbolism of religion, but also can meet our's expectations of utilization of modern textile art, art clothing and wide-all division of design. These give the understanding of symbolic meanings and harmony according to liturgical vestments to the believers. And these have an influence on mental thinking and induction of religious belief to the non-believers as the recognition and concerns about the religious art. The liturgical vestments are clothes which churchmen put on at the all ceremonial function of a mass, a sacrament, performance and a parade according to rules of church. These show the represen-tation of "Holy God" in silence and distinguish between common people and churchmen. And these represent a status and dignity of churchmen and induce majesty and respect to churchmen. Common clothes of the beginning of the Greece and Rome was developed to Christian clothes with the tendency of religion. There were no special uniforms distinguished from commen people until the Christianity was recognized officially by the Roman Emperor Constantinus at A.D.313. The color of liturgical vestments was originally white and changed to special colors according to liturgical day and each time by the Pope Innocentius at 12th century. The color and symbolic meaning of the liturgical vestments of present day was originated by the Pope St. Pius(1566-1572). Wool and Linen was used as decorations and materials in the beginnings and the special materials like silk was used after 4th century and beautiful materials made of gold thread was used at 12th century. It is expected that there is no critical changes to the liturgical vestments of future. But the development of liturgical vestments will continues slowly by the command of conservative church and will change to simple and convenient formes according to the culture, the trend of the times and the fashion of clothes. The companies of liturgical vestments develop versatile design, embroidery technique and realization of creative design for distinction of the liturgical vestments of each company and artistic progress. The cooperation of companies, artists and church will make the bright future of these 3 companies. We expect that our country will be a famous producing center of the liturgical vestments through the research and development of companies, participation of artists in religeous arts and concerts of church.

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Comparision of Chest Radiographs and Pulmonary Function in Coal Workers' Pneumoconiosis and Welders' Lung (탄광부 진폐증과 용접공 폐증에 있어 흉부-X선 소견과 폐기능의 비교)

  • Park, Dong-Youl;Hwang, Joo-Ho;Kang, Byung-Son;Chung, Chan-Su;Kim, Wha-Jo
    • Tuberculosis and Respiratory Diseases
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    • v.42 no.5
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    • pp.713-722
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    • 1995
  • Background: Chest X-ray of coal workers' pneumoconiosis and shipyard welders' lung show similar and regular opacities mostly, it is very difficult that we distinguish the former from the latter by only chest X-ray. so we performed this study to understand the progression of the disease and to provide the disease by considering pulmonary function and other factors in proportion to the profusion of small regular opacities of chest X-ray in both groups. Method: 430 coal workers' pneumoconiosis were compared with 311 shipyard welders' lung by the number, the age, the duration of dust exposure, %vital capacity(%VC), %FEV1.0, the type of ventilatory impairment, the combined pulmonary disease according to the profusion of small regular opacities on the chest radiographs, which were classified into category 0/1, category 1, and category 2. Result: 1) the percent of category 2 in coal workers' pneumoconiosis was 54.4%. the percent of category 1, and category 2 in welders' lung were 60.0%, 7.4%. the progression to the category 2 was higher in coal workers' pneumoconiosis than in welders' lung 2) The mean age was higher in coal workers' pneumoconiosis than in welders' lung, significantly increased in proportion to the progresion of profusion of small regular opacities in both groups 3) There was no difference in the duration of dust exposure by category 1/0, but the duration of dust exposure by category 1, 2 in coal workers' pneumoconiosis more significantly increased than in welders' lung. the duration in the proportion of category 2 to category 0/1, 1 significantly increased in the proportion to small regular opacities in coal workers' pneumoconiosis. but there was no significant difference in the proportion to small regular opacities in duration of dust exposure in welders' lung. 4) There was no significant difference of mean values of %VC(%vital capacity)in both groups except for category 1. the mean values of %VC had no relationship between the progression of small regular opacities in both groups. 5) The mean values of %FEV1.0 decreased more significantly in coal workers' pneumoconiosis than in welders' lung except for category 0/1. and decreased significantly in proportion to the profusion of small regular opacities in coal workers' pneumoconiosis. there was significant difference of %FEV1.0 in the proportion of category 2 to category 011 in welders' lung. 6) there were no significant difference of %FEV1.0, %VC in smoker and nonsmoker in both groups. 7) With regard to the type of ventilation in both groups in coal workers' pneumoconiosis 21.4 percent of patients belonged to the restrictive type, 11.6 percent to the obstructive type, 5.6 percent to the combined type, but in welders' lung 21.8 percent to the restrictive type, 2.9 percent to the obstructive type, 1.9 percent to the combined type. 8. in the pulmonary disease, the incidence of the pulmonary tuberculosis was the most in both groups, was more in coal workers' pneumoconiosis than welders' lung Conclusion: If we compare coal workers' pneumoconiosis with electric arc welders'lung by considering pulmonary function and other factors in proportion to the profusion of chest X-ray, I think that we will have the better result in understanding the progression of the disease and provision of the disease in both groups.

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Determination of Minimal Pressure Support Level During Weaning from Pressure Support Ventilation (압력보조 환기법으로 기계호흡 이탈시 최소압력보조(Minimal Pressure Support) 수준의 결정)

  • Jung, Bock-Hyun;Koh, Youn-Suck;Lim, Chae-Man;Lee, Sang-Do;Kim, Woo-Sung;Kim, Dong-Soon;Kim, Won-Dong
    • Tuberculosis and Respiratory Diseases
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    • v.45 no.2
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    • pp.380-387
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    • 1998
  • Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

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