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Dietary Habits and Foodservice Attitudes of Students Attending American International Schools in Seoul and Gyeonggi Area (서울.경기지역 외국인 학교 학생들의 식습관 및 급식만족도 -미국계 외국인 학교를 중심으로-)

  • Kim, Ok-Sun;Lee, Young-Eun
    • Journal of the East Asian Society of Dietary Life
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    • v.22 no.6
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    • pp.744-757
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    • 2012
  • This study was designed to obtain basic data for the globalization of Korean food and the expansion of food exports through contract foodservices. A survey of dietary habits and attitudes toward school foodservices was given to students in three American international schools served by a domestic contract foodservice management company located in Seoul and Gyeonggi area. The results showed an average of three meals taken daily 3.39 times for male students and 2.95 times for female students and the time required for a meal was about 24~26 minutes. The average breakfast frequency was 5.10 times(4.59 times for male students and 5.35 times for female students) and many students reported skipping breakfast due to a lack of time. The average weekly frequency of dining out was 1.78 times(2.15 times for male students and 1.60 times for female students). In all schools, irrespective of gender and grade, students responded that a desire for snacking was 'why they want to have cookies', and snacking hours were frequently listed as 'between noon and evening'. Many also responded that an unbalanced diet is the reason some snacks are 'not to their taste'. Overall, students were highly satisfied with the foodservice menu, although there was a significant difference in what was considered proper food temperature, proper food seasoning, suitable amounts of food, and freshness of food. Male and female students were specifically highly satisfied with the 'freshness of food materials' and 'variety of menu' respectively. Overall, all students were highly satisfied with the foodservice, including the 'cleanliness of tables and trays'.

Study on Types and Counterplans of Medical Accident Experienced by Dentists in Seoul(2004) (서울특별시 개원 치과의사의 의료사고 및 분쟁의 유형과 대책에 관한 연구(2004년))

  • Yoon, Jeong-Ah;Kang, Jin-Kyu;Ahn, Hyoung-Joon;Choi, Jong-Hoon;Kim, Chong-Youl
    • Journal of Oral Medicine and Pain
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    • v.30 no.2
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    • pp.163-199
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    • 2005
  • Dentistry had been considered to be a relatively safe zone from the risk of medical accidents for there are less number of emergency cases. However, in these days, the number of medical dispute is increasing that the dentists would not be able to overlook it as if it is none of their matters. Hence, researches on various medical accidents and analyses on related matters to seek proper management have been carried out recently, but the datas are not enough yet. This study analysed the actual conditions of medical accidents as well as disputes and the general awareness of dental practitioners in local clinics with the purpose of understanding the general situation and to suggest counterplan. The study was conducted by analysing 1,882 questionnaires collected from total of 3,684 dentists belonging to Seoul Dental Association and where Doctors and Hospitals Medical Malpractice Insurance for dentists is administered. The results were as follows: 1. 98.47% of the respondents doubted the risk of medical accident and dispute. 2. 27.42% of the respondents experienced medical dispute, and there was no significant difference between the rate of medical disputes and the resident training. 3. Among the cases of medical accidents, those related to the periodontal/operative treatment showed the highest rate of 20.50%, and that related to implant treatment was 6.17%. 4. 43.02% of the respondents explained about the treatment procedure before the treatment while 25.90% started the treatment without consent of the patients. 5. Medical dispute resulted from not having any explanation or consent of the patients were of 16.55%. 10.26% had difficulties in solving the problem for missing the medical records. 6. 49.73% responded to be capable of administering first aid treatment. Among them, 23.60% were equipped with accurate knowledge regarding the emergency care. 7. During medical dispute, 88.09% sought counsel from other dentists, and Local district dental association was found to be the most frequently asked group. 8. In cases of medical dispute, 5.26% of the respondents were asked to submit relevant data from customer protection organization, and among them, 75.61% acceded the demand sincerely. 9. After the settlement of the dispute, 83.63% recovered relatively stable state of mind. 10. 99.46% of the respondents felt the necessity of medical dispute management organization, and 78.58% responded that it was urgent. 11. 66.70% of the respondents joined Doctors and Hospitals Medical Malpractice Insurance, although they had not experienced medical dispute. However, 73.36% of the respondent were not aware of it, and 93.36% of the members were not aware of the procedure of the dispute settlement. 12. 79.0% of the respondents who joined the Doctors and Hospitals Medical Malpractice Insurance still felt confused when medical dispute occured, but relatively safer than before. 13. When medical dispute was settled through Doctors and Hospitals Medical Malpractice Insurance, 71.92% of the dentists were contented more than moderately, however, 35.16% of the patients were contented. 14. For complement of Doctors and Hospitals Medical Malpractice Insurance, 53.22% of the respondents felt that insurance company, dentist, and patient should all participate in bringing mutual agreement for quick settlement of the dispute. In addition, 29.08% of the respondents wanted insurance company to prevent patients from disturbing their practices. From the above results, improvement of the general awareness on increasing rate of medical disputes, and education as well as complementary measures for settlement of the disputes are required.

The Early Experience with a Totally Laparoscopic Distal Gastrectomy (전(全)복강경하 원위부 위절제술의 초기 경험)

  • Kim Jin Jo;Song Gyo Young;Chin Hyung Min;Kim Wook;Jeon Hae Myoung;Park Cho Hyun;Park Seung Man;Lim Keun Woo;Park Woo Bae;Kim Seung Nam
    • Journal of Gastric Cancer
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    • v.5 no.1
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    • pp.16-22
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    • 2005
  • Purpose: In Korea, the number of laparoscopy-assisted distal gastrectomies for early gastric cancer patients has been increasing lately. Although minimally invasive surgery is more beneficial, no reported case of a totally laparoscopic distal gastrectomy has been reported because of difficulty with intracorporeal anastomosis. This study attempts, through our experiences, to determine the feasibility of a totally laparoscopic distal gastrectomy using an intracorporeal gastroduodenostomy in treating early gastric carcinoma. Materials and Methods: We investigated surgical results and clinicopatholgic characteristics of eight(8) patients with an early gastric carcinoma who underwent a totally laparoscopic distal gastrectomy at the Department of Surgery, Our Lady of Mercy Hospital, The Catholic University of Korea, between June 2004 and September 2004. The intracorporeal gastroduodenostomy was performed with a delta-shaped ananstomosis by using only laparoscopic linear staplers (Endocutter 45mm; Ethicon Endosurgery, OH, USA). Results: The operative time was $369.4\pm62.5$ minutes (range $275\∼465$ minutes), and the anastomotic time was 45.1\pm14.4$ minutes (range $32\∼70$ minutes). The anastomotic time was shortened as surgical experience was gained. The number of laparoscopic linear staplers for an operation was $7.1\pm0.6$. The number of lymph nodes harvested was $31.9\pm13.1$. There was 1 case of transfusion and no case of conversion to an open procedure. The time to the first flatus was 2.8$\pm$0.5 days, and the time to the first food intake was $4.1\pm0.8$ days. There were no early postoperative complications, and the postoperative hospital stay was $10.0\pm3.9$ days. Conclusion: A totally laparoscopic distal gastrectomy using an intracorporeal gastroduodenostomy with a delta-shaped anastomosis is technically feasible and can maximize the benefit of laparoscopic surgery for early gastric cancer.

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An Appreciation of Functional Role of Macrophage in the Acute Lung Injury in the Neutropenic Rat. (호중구 감소증을 보이는 백서의 급성폐손상에서 대식세포의 기능적 역할)

  • Kim, Yong-Hoon;Ki, Sin-Young;Im, Keon-Il;Moon, Seung-Hyug;Cheong, Seung-Whan;Kim, Hyeon-Tae;Uh, Soo-Taek;Park, Choon-Sik;Jin, Byung-Won
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.2
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    • pp.379-390
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    • 1997
  • Background : It has long been suggested that neutrophils and their products are implicated as the central mediators of the acute lung injuries. Contrary to the dominant role of neutrophils in ARDS, many cases of ARDS has occurred in the setting of severe neutropenia without pulmonary neutrophil infiltration. Therefore it is certain that effector cell(s) other than neutrophil play an important role in the pathogenesis of ARDS. This experiment was performed to define the mechanism of ARDS in the setting of neutropenia, 1) by comparing the severity of endotoxin-induced lung injury, 2) by measurement of hydrogen peroxide production and cytokine concentration in the bronchoalveolar lavage cells and fluids obtained from different rats with and without cyclophosphamide-pretreatment. Method : The male Sprague-Dawleys were divided into the normal control (NC)-, endotoxin (ETX)-, and cyclophosphamide (CPA)-group in which neutropenia was induced by injecting cyclophosphamide intraperitoneally. Acute lung injury was evoked by injecting lipopolysaccharide (LPS) into a tail vein. The bronchoalveolar lavage (BAL) was performed at 3 and 6 hour after administration of LPS to measure the change of cell counts and concentrations of protein and cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Hydrogen peroxide (HPO) production from BAL cells was measured at 6 hour after LPS administration by phenol red microassay with and without zymosan stimulation. Results : The results were as follows. A change of leukocyte counts in the peripheral blood after treatment with CPA : More than 95% of total leukocytes and neutrophils were reduced after CPA administration, resulting in severe neutropenia. A change of BAL cells : In the ETX-group, the number of total cells (p < 0.01) and of macrophage and neutrophil (p < 0.05) were increased at 3 and 6 hour after LPS administration compared to those of NC-group. In the CPA-group, the number of total leukocyte and macrophage were not changed after LPS administration, but neutrophil counts were significantly reduced and it took part in less than 0.1% of total BAL cells (p < 0.01 vs NC-group). BAL cells in this group were almost all macrophages (99.7%). A change of protein concentration in the BALF : In the ETX-group, protein concentration was increased at 3 hour and was more increased at 6 hour after LPS administration (p < 0.05 and < 0.01 vs NC-group, respectively). In the CPA-group, it was also significantly elevated at 3 hour after LPS administration (p < 0.05 vs NC-group), but the value was statistically not different from that of ETX-group. The value measured at 6 hour after LPS administration in the CPA-group became lower than that of ETX-group (p < 0.05), but showed still a higher value compared to that of NC-group (p < 0.05). A change of cytokine concentration in the BALF : TNF -alpha and IL-6 were elevated in the ETX - and CPA-group compared to those of NC-group at both time intervals. There was no statistical difference in the values of both cytokines between the ETX- and CPA-groups. Measurement of hydrogen peroxide production from BAL cells : There was no intergroup difference of HPO production from resting cells. HPO production after incubation with opsonized zymosan was significantly elevated in all groups. The percent increment of HPO production was highest in the ETX-group (89.0%, p < 0.0008 vs NC-group), and was 42.85 in the CPA-group (p = 0.003 vs NC-group ). Conclusion : Acute lung injury in the setting of neutropenia might be caused by functional activation of resident alveolar macrophages.

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The Role of Protein Kinase C in Acute Lung Injury Induced by Endotoxin (내독소에 의한 급성폐손상에서 Protein Kinase C의 역할)

  • Kim, Yong-Hoon;Moon, Seung-Hyug;Kee, Sin-Young;Ju, Jae-Hak;Park, Tae-Eung;Im, Keon-Il;Cheong, Seung-Whan;Kim, Hyeon-Tae;Park, Choon-Sik;Jin, Byung-Won
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.2
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    • pp.349-359
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    • 1997
  • Background : The signal pathways and their precise roles for acute respiratory distress syndrome caused by endotoxin (ETX) has not been established. Since there has been several in vitro experiments suggesting that activation of protein kinase C (PKC) pathway may be responsible for endotoxin-induced inflammatory reaction, we performed in vivo experiments in the rats with the hypothesis that PKC-inhibition can effectively prevent endotoxin-induced acute lung injury. Methods : We studied the role of PKC in ETX-induced ALI using PKC inhibitor (staurosporine, STP) in the rat Specific pathogen free male Sprague-Dawley weighted from 165 to 270g were used for the study. Animals were divided into the normal control (NC)-, vehicle control (VC)-, ETX-, PMA (phorbolmyristateacetate)-, STP+PMA-, and STP+ETX-group. PMA (50mg/kg) or ETX (7mg/kg) was instilled through polyethylen catheter after aseptic tracheostomy with and without STP (0.2mg/kg)-pretreatment STP was injected via tail vein 30min before intratracheal injection (IT) of PMA or ETX. Bronchoalveolar lavage (BAL) was done 3-or 6-hrs after IT of PMA or ETX respectively, to measure protein concentration, total and differential cell counts. Results : The results were as follows. The protein concentrations in BALF in the PMA- and ETX-group were very higher than that of VC-group (p<0.001). When animals were pretreated with STP, the %reduction of the protein concentration in BALF was $64.8{\pm}8.5$ and $30.4{\pm}2.5%$ in the STP+PMA- and STP+ETX-group, respectively (p = 0.028). There was no difference in the total cell counts between the PMA-and VC-group (p = 0.26). However the ETX-group showed markedly increased total cell counts as compared to the VC- (p = 0.003) and PMA-group (p = 0.0027), respectively. The total cell counts in BALF were not changed after pretreatment with STP compared to the PMA- (p = 0.22) and ETX-group (p = 0.46). The percentage of PMN, but not alveolar macrophage, was significantly elevated in the PMA-, and ETX-group. Especially in the ETX-group, the percentage of PMN was 17 times higher than that of PMA (p < 0.001). The differential cell counts was not different between the PMA and STP+PMA On the contrary the STP+ETX-group showed decreased percentage of PMN (p = 0.016). There was no significant relationship between the protein concentration and the total or differential cell counts in each group. Conclusion : Pretreatment with PKC-inhibitor (staurosporine) partially but significantly inhibited ETX-induced ALI.

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Efficacy and Safety of Early Bronchoscopy in Patients with Hemoptysis (객혈환자에서 조기기관지경의 유용성 몇 안정성)

  • Kim, Ho-Cheol;Cheon, Eun-Mee;Chung, Man-Pyo;Kim, Ho-Joong;Choi, Dong-Chull;Kwon, O-Jung;Rhee, Chong-H.;Han, Yong-Chol
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.2
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    • pp.391-400
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    • 1997
  • Background : Bronchoscopy is an essential procedure for identifying the bleeding site and evaluating cause of hemoptysis. However, it is controversial regarding to the timing of bronchoscopy in patients with hemoptysis. Early bronchoscopy, which was performed during hemoptysis or with 48hour after cessation of bleeding, was better for identifying the site of bleeding compared with delayed bronchoscopy, which was performed 48 hours after cessation of bleeding. The diagnostic yield of identifying the bleeding site by bronchoscopy was variable in reported literature and the safety of early bronchoscopy was not mentioned in previous literature. Therefore, we evaluated the efficacy and safety of early bronchoscopy in patients with hemoptysis. Method : From October 1994 to August 1996 in Samsung Medical Center, bronchoscopy was performed in patients with hemoptysis. Early bronchoscopy was performed prospectively during hemoptysis or within 48 hours after cessation of bleeding from May 1995 to August 1996. Delayed bronchoscopy group included patients who did not received early bronchoscopy at the same period or in whom bronchoscopy was performed 48 hour after cessation of bleeding from October 1994 to May 1995. Results : Early bronchoscopy group was performed 73 times in 71 patients. Delayed bronchoscopy was performed in 57 times in 55 patients. There was no difference as to amount and underlying cause of hemoptysis between both groups. Indentification of bleeding site by visualizing active bleeding was significantly higher in early bronchoscopy (38.3%) than delayed bronchoscopy group (8.7%)(p < 0.05). Indentification of bleeding site by bleeding after clot removal was 8 in early and 10 in delayed bronchoscopy. Indentification of bleeding site by visualizing active bleeding and bleeding after clot removal was 36 in early and 15 patients in delayed bronchoscopy(p > 0.05). Causes of hemoptysis was found in 18 patients in early and 16 patients in delayed bronchoscopy group. patients who had early bronchoscopy underwent surgery. We diagnosed the site of bleeding in 4 patients preoperatively. In 3 patients we made a treatment plan promptly right after bronchoscopy. Among early bronchoscopy group, bleeding over 100cc during bronchoscopy occurred in 2 patients. In early bronchoscopy group there was no other major complication during bronchoscopy. Conclusion : In patients with hemoptysis, early bronchoscopy which performed within 48 hours after cessation of bleeding was more effective procedure for identifying the bleeding site than delayed bronchoscopy which was performed after 48 hour cessation of bleeding.

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The Effect of Glucocorticoid on the Change of Nitric Oxide and Cytokine Levels in Induced Sputum from Patients with Bronchial Asthma (기관지 천식 환자에서 부신피질 스테로이드 투여 전후 유도객담내 Nitric Oxide 및 Cytokine의 변화)

  • Kim, Tae-Yon;Yoon, Hyeong-Kyu;Choi, Young-Mee;Lee, Sook-Young;Kwon, Soon-Seog;Kim, Young-Kyoon;Kim, Kwan-Hyoung;Moon, Hwa-Sik;Park, Sung-Hak;Song, Jeong-Sup
    • Tuberculosis and Respiratory Diseases
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    • v.48 no.6
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    • pp.922-931
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    • 2000
  • Background : It has been well known that bronchia1 asthma is a chronic airway inflammatory disorder. Recently, sputum induced with hypertonic saline was introduced as a simple and useful nonivasive medium to investigate airway inflammation and symptom severity in patients with asthma. We examined the eosinophil, eosinophil cationic protein (ECP), interleukin(IL)-3, IL-5, granulocyte-macrophage colony-stimulating facta (GM-CSF), and nitric oxide (NO) derivatives in induced sputum from patients with bronchia1 asthma in order to determine the role of NO and various inflammatory cytokines as a useful markers of airway inflammation or changes in pulmonary function tests and symptoms. Methods : A total 30 patients with bronchia1 asthma received oral prednisolone 30 mg daily for 2 weeks. Forced expiratory volume in one second ($FEV_1$), total blood eosinophil count and induced sputum eosinophil count, ECP, IL-3, IL-5, GM-CSF, and NO derivatives were determined before and after the administration of prednisolone. Results : Of the 30 patients, 13 (43.3%) were male and 17 (56.7%) were female. The mean age of patients was 41.8 years (range 19-64 years). Two patients could not produce sputum at the second study and 3 could not be followed up after their first visit. Two weeks after the prednisolone administration, there was a significant increase in $FEV_1$ (% of predicted value) from 78.1$\pm$20.6 % to 90.3$\pm$ 18.3 % (P<0.001). The eosinophil percentages in induced sputum were significantly decreased after treatment with prednisolone, with values of 56.1$\pm$27.2 % versus 29.6$\pm$21.3 % (P<0.001), and ECP were $134.5\pm68.1\;{\mu}g/L$ versus $41.5\pm42.4\;{\mu}g/L$ (P<0.001) respectively. After the prednisolone treatments, the eotaxin concentration also showed a decreasing tendency from 26.7$\pm$12.8 pg/ml to 21.7$\pm$8.7 pg/ml. There was a decreasing tendency but no significant differences in total blood eosinophil count (425.7$\pm$265.9 vs 287.7$\pm$294.7) and in the concentration of NO derivatives ($70.4\pm44.6{\mu}mol/L$ vs $91.5\pm48.3\;{\mu}mol/L$) after the prednisolone treatments. IL-3, IL-5, GM-CSF were undetectable in the sputum of most subjects either before the prednisolone treatments or after the treatments. Before the prednisolone treatments, a significant inverse correlation was observed between FEV1 and sputum ECP (r=-D.364, P<0.05) and there was a significant correlation between sputum eosinophils and eotaxin (r=0.369, P<0.05) Conclusion : The eotaxin and ECP concentration in induced sputum may be used as markers of airway inflammation after treatments in bronchia1 asthma. In addition, the measurement of sputum eosinophil percent ages is believed to be a simple method displaying the degree of airway inflammation and airway obstruction before and after the prednisolone treatment in bronchia1 asthma. However, unlike exhaled NO, the examination of NO derivatives with Griess reaction in induced sputum is considered an ineffective marker of changing airway inflammation and obstructing symptoms.

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Chemokine Secretion From Alveolar Macrophages in Patients with Diffuse Interstitial Lung Diseases(DILD) (미만성 간질성 폐질환 환자들의 폐포대식세포의 chemokine(MIP-1, IL-8) 분비능에 관한 연구)

  • Kim, Dong Soon;Paik, Sang Hoon;Lim, Chae Man;Lee, Sang Do;Koh, Younsuck;Kim, Woo Sung;Kim, Won Dong
    • Tuberculosis and Respiratory Diseases
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    • v.43 no.6
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    • pp.954-964
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    • 1996
  • Background : The type of the infiltrating cells in al veolitis may be determined by the chemokines in the lesion. MIP-1 ${\alpha}$, a C-C type chemokine, stimulates proliferation and cytokine secretion from macrophages and induces early neutrophilic and later monocytic inflammation in vi vo. IL-8, a C-X-C type chemokine is known to attract neutrophils and T-lymphocytes. This study is performed to find out the relative role of two different chemokines in diffuse interstitial lung disease. Subject and Method : We measured the secretion of MIP- 1 ${\alpha}$ and IL-8 from alveolar macrophages(AM), and their level in BAL fluid of 26 patients with DILD (10 IPF, 4 collagen disease, 10 sarcoidosis, and 2 hypersensitivity pneumonitis) and 7 normal control. Result: IL-8 secretion was significantly increased in patients with DILD ($8.15{\pm}4.58$ ng/ml) than in normal ($1.10{\pm}0.93$ ng/ml, p=0.0003). Significant correlation was found between IL-8 secretion and total cell number in BAL fluid (r=0.484, p=0.0068), %(r=0.592, p=0.0004) and No. (r=0.516, p=0.0042) of lymphocyte, and % of AM (r=-0.505, 0.0032). MIP- 1 ${\alpha}$ secretion was also increased in DILD ($2.41{\pm}1.45$ ng/ml) compared to control ($0.63{\pm}0.30$ ng/ml, p=0.0031), and showed a tendency of correlation with total cell number (r=0.368, p=0.0456) and No. of alveolar macrophages (r=0.356, p=0.0579) in BAL fluid. The concentration of IL-8 in BAL fluid was significantly increased in the patients with DILD ($40.4{\pm}34.5$ pg/ml) compared to control ($3.90{\pm}2.47$ pg/ml, p=0.0094) and it showed a significant correlation with the total cell number (r=0.484, p=0.0068), %(r=-0.505, p=0.0032) of AM, and % (r=0.592, p=0.0004) and No. (r=0.516, p=0.0042) of lymphocyte in BAL fluid. But there was a no significant difference in MIP- 1 ${\alpha}$ concentration in BAL fluid between normal control group and the patients with DILD. Conclusion : From the above results, we concluded that AM of DILD releases increased amount of both IL-8 and MIP- 1 ${\alpha}$ but IL-8 has better correlation with the type of alveolitis.

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Studies on Stability for the Quality of Ginseng Products -5. Improvement of Physical Properties on Moisture Sorption of Spray Dried Red Ginseng Extract Powder- (인삼제품(人蔘製品)의 품질안정성(品質安定性)에 관한 연구(硏究) -5. 홍삼정분(紅蔘精粉)의 흡습물성(吸濕物性) 개선(改善)-)

  • Choi, Jin-Ho;Byun, Dae-Seok;Ro, Jae-Il;Park, Kil-Dong;Sung, Hyun-Soon
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.13 no.3
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    • pp.251-258
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    • 1984
  • In order to improve the physical properties on moisture sorption of spray dried red ginseng extract powder (SD-RGEP), the various additives and coating agents were treated, and solubility, sedimentation rate and storage stability of RGEPs treated were investigated. For the moisture-proofing, additive itself was effective in the order casein>dextrin>starch>avicell, but RGEPs treated with additives were effective in the order cord oil+tween-40>starch>casein. But there was no significant difference between RGEP treated less than 1% additive and the moisture-proofing. The coating effect of AEA and CAP on RGEP could not be recognized for the moisture-proofing, whereas that of HPC, corn oil, lecithin and HPC+corn oil was proved to be very effective for the moisture-proofing of RGEP. Also it is required to control the initial moisture content of RGEP. The sedimentation rate of RGEP nontreated was 65.1 seconds, whereas that of RGEPs coated with 1% HPC, 1% corn oil, 1% lecithin and 1% HPC+0.5% corn oil was in the range of 96.2 to 114.3 seconds. The sedimentation rate of RGEPs coated was 1.5 to 1.8 times higher than that of RGEP nontreated, and there was significant difference between solubility and sedimentation rate. Therefore it was no matter for the keeping quality. The sorption rates of RGEPs coated with lecithin $(0.5{\sim}1.0%$), corn oil(0.8%) and cellulose acetate (0.8%) were ranged 54 to 56%, 51 to 55% and 52 to 54%, respectively, and it is found that the moisture-proofing effect of RGEPs coated was about 2 times higher than that of RGEP nontreated. From the result of storage experiment during 3 months under the maltreated condition of $48{\pm}2^{\circ}C$, 75% RH, the moisture sorption of RGEPs coated with corn oil$(0.5{\sim}1.0%$), cellulose acetate(DES, $0.5{\sim}0.8%$) and lecithin (DES, 1.0%) was not at all observed. Therefore it is considered that the circulating period of RGEPs coated with these coating agents could to give more than 3 years.

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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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