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Smoking-Induced Dopamine Release Studied with $[^{11}C]Raclopride$ PET ($[^{11}C]Raclopride$ PET을 이용한 흡연에 의한 도파민 유리 영상 연구)

  • Kim, Yu-Kyeong;Cho, Sang-Soo;Lee, Do-Hoon;Ryu, Hye-Jung;Lee, Eun-Ju;Ryu, Chang-Hung;Jeong, In-Soon;Hong, Soo-Kyung;Lee, Jae-Sung;Seo, Hong-Gwan;Jeong, Jae-Min;Lee, Won-Woo;Kim, Sang-Eun
    • The Korean Journal of Nuclear Medicine
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    • v.39 no.6
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    • pp.421-429
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    • 2005
  • Purpose: It has been postulated that dopamine release in the striatum underlies the reinforcing properties of nicotine. Substantial evidence in the animal studies demonstrates that nicotine interacts with dopaminergic neuron and regulates the activation of the dopaminergic system. The aim of this study was to visualize the dopamine release by smoking in human brain using PET scan with $[^{11}C]raclopride$. Materials and Methods: Five male non-smokers or ex-smokers with an abstinence period longer than 1 year (mean age of $24.4{\pm}1.7$ years) were enrolled in this study $[^{11}C]raclopride$, a dopamine D2 receptor radioligand, was administrated with bolus-plus-constant infusion. Dynamic PET was performed during 120 minutes ($3{\times}20s,\;2{\times}60s,\;2{\times}120s,\;1{\times}180s\;and\;22{\times}300s$). following the 50 minute-scanning, subjects smoked a cigarette containing 1 mg of nicotine while in the scanner. Blood samples for the measurement of plasma nicotine level were collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 90 minute after smoking. Regions for striatal structures were drawn on the coronal summed PET images guided with co-registered MRI. Binding potential, calculated as (striatal-cerebellar)/cerebellar activity, was measured under equilibrium condition at baseline and smoking session. Results: The mean decrease in binding potential of $[^{11}C]raclopride$ between the baseline and smoking in caudate head, anterior putamen and ventral striatum was 4.7%, 4.0% and 7.8%, respectively. This indicated the striatal dopamine release by smoking. Of these, the reduction in binding potential in the ventral striatum was significantly correlated with the cumulated plasma level of the nicotine (Spearman's rho=0.9, p=0.04). Conclusion: These data demonstrate that in vivo imaging with $[^{11}C]raclopride$ PET could measure nicotine-induced dopamine release in the human brain, which has a significant positive correlation with the amount or nicotine administered bt smoking.

The Comparison of Image Quality and Quantitative Indices by Wide Beam Reconstruction Method and Filtered Back Projection Method in Tl-201 Myocardial Perfusion SPECT (Tl-201 심근관류 SPECT 검사에서 광대역 재구성(Wide Beam Reconstruction: WBR) 방법과 여과 후 역투영법에 따른 영상의 질 및 정량적 지표 값 비교)

  • Yoon, Soon-Sang;Nam, Ki-Pyo;Shim, Dong-Oh;Kim, Dong-Seok
    • The Korean Journal of Nuclear Medicine Technology
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    • v.14 no.2
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    • pp.122-127
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    • 2010
  • Purpose: The Xpress3.$cardiac^{TM}$ which is a kind of wide beam reconstruction (WBR) method developed by UltraSPECT (Haifa, Israel) enables the acquisition of at quarter time while maintaining image quality. The purpose of this study is to investigate the usefulness of WBR method for decreasing scan times and to compare to it with filtered back projection (FBP), which is the method routinely used. Materials and Methods: Phantom and clinical studies were performed. The anthropomorphic torso phantom was made on an equality with counts from patient's body. The Tl-201 concentrations in the compartments were 74 kBq (2 ${\mu}Ci$)/cc in myocardium, 11.1 kBq (0.3 ${\mu}Ci$)/cc in soft tissue, and 2.59 kBq (0.07 ${\mu}Ci$)/cc in lung. The non-gated Tl-201 myocardial perfusion SPECT data were acquired with the phantom. The former study was scanned for 50 seconds per frame with FBP method, and the latter study was acquired for 13 seconds per frame with WBR method. Using the Xeleris ver. 2.0551, full width at half maximum (FWHM) and average image contrast were compared. In clinical studies, we analyzed the 30 patients who were examined by Tl-201 gated myocardial perfusion SPECT in department of nuclear medicine at Asan Medical Center from January to April 2010. The patients were imaged at full time (50 second per frame) with FBP algorithm and again quarter-time (13 second per frame) with the WBR algorithm. Using the 4D MSPECT (4DM), Quantitative Perfusion SPECT (QPS), and Quantitative Gated SPECT (QGS) software, the summed stress score (SSS), summed rest score (SRS), summed difference score, end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were analyzed for their correlations and statistical comparison by paired t-test. Results: As a result of the phantom study, the WBR method improved FWHM more than about 30% compared with FBP method (WBR data 5.47 mm, FBP data 7.07 mm). And the WBR method's average image contrast was also higher than FBP method's. However, in result of quantitative indices, SSS, SDS, SRS, EDV, ESV, EF, there were statistically significant differences from WBR and FBP(p<0.01). In the correlation of SSS, SDS, SRS, there were significant differences for WBR and FBP (0.18, 0.34, 0.08). But EDV, ESV, EF showed good correlation with WBR and FBP (0.88, 0.89, 0.71). Conclusion: From phantom study results, we confirmed that the WBR method reduces an acquisition time while improving an image quality compared with FBP method. However, we should consider significant differences in quantitative indices. And it needs to take an evaluation test to apply clinical study to find a cause of differences out between phantom and clinical results.

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Improvement in Regional Contractility of Myocardium after CABG (관상동맥 우회로 수술 환자에서 심근의 탄성도 변화)

  • Lee, Byeong-Il;Paeng, Jin-Chul;Lee, Dong-Soo;Lee, Jae-Sung;Chung, June-Key;Lee, Myung-Chul;Choi, Heung-Kook
    • The Korean Journal of Nuclear Medicine
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    • v.39 no.4
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    • pp.224-230
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    • 2005
  • Purpose: The maximal elastance ($E_{max}$) of myocardium has been established as a reliable load-independent contractility index. Recently, we developed a noninvasive method to measure the regional contractility using gated myocardial SPECT and arterial tonometry data. In this study, we measured regional $E_{max}(rE_{max}$ in the patients who underwent coronary artery bypass graft surgery (CABG), and assessed its relationship with other variables. Materials and Methods: 21 patients (M:F=17:4, $58{\pm}12$ y) who underwent CABG were enrolled. $^{201}TI$ rest/dipyridamole stress $^{99m}Tc$-sestamibi gated SPECT were performed before and 3 months after CABG. For 15 myocardial regions, regional time-elastance curve was obtained using the pressure data of tonometry and the volume data of gated SPECT. To investigate the coupling with myocardial function, preoperative regional $E_{max}$ was compared with regional perfusion and systolic thickening. In addition, the correlation between $E_{max}$ and viability was assessed in dysfunctional segments (thickening <20% before CABG). The viability was defined as improvement of postoperative systolic thickening more than 10%. Results: Regional $E_{max}$ was slightly increased after CABG from $2.41{\pm}1.64 (pre)\;to\;2.78{\pm}1.83 (post)$ mmHg/ml. $E_{max}$ had weak correlation with perfusion and thickening (r=0.35, p<0.001). In the regions of preserved perfusion (${\geq}60%$), $E_{max}$ was $2.65{\pm}1.67$, while it was $1.30{\pm}1.24$ in the segments of decreased perfusion. With regard to thickening, $E_{max}$ was $3.01{\pm}1.92$ mmHg/ml for normal regions (thickening ${geq}40%$), $2.40{\pm}1.19$ mmHg/ml for mildly dysfunctional regions (<40% and ${\geq}20%$), and $1.13{\pm}0.89$ mmHg/ml for severely dysfunctional regions (<20%). $E_{max}$ was improved after CABG in both the viable (from $1.27{\pm}1.07\;to\;1.79{\pm}1.48$ mmHg/ml) and non-viable segments (from $0.97 {\pm}0.59\;to\;1.22{\pm}0.71$ mmHg/ml), but there was no correlation between $E_{max}$ and thickening improvements (r=0.007). Conclusions: Preoperative regional $E_{max}$ was relatively concordant with regional perfusion and systolic thickening on gated myocardial SPECT. In dysfunctional but viable segments, $E_{max}$ was improved after CABG, but showed no correlation with thickening improvement. As a load-independent contractility index of dysfunctional myocardial segments, we suggest that the regional $E_{max}$ could be an independent parameter in the assessment of myocardial function.

The Cox-Maze Procedure for Atrial Fibrillation Concomitant with Mitral Valve Disease (승모판막질환에 동반된 심방세동에서 Cox-Maze 술식)

  • Kim, Ki-Bong;Cho, Kwang-Ree;Ahn, Hyuk
    • Journal of Chest Surgery
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    • v.31 no.10
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    • pp.939-944
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    • 1998
  • Background: The sugical results of the Cox-Maze procedure (CMP) for lone atrial fibrillation(AF) have proven to be exellent. However, those for AF associated with mitral valve(MV) disease have been reported to be a little inferior. Materials and methods: To assess the efficacy and safety of the CMP as a combined procedure with MV operation, we studied retrospectively our experiences. Between April 1994 and October 1997, we experienced 70 (23 males, 47 females) cases of CMP concomitantly with MV operation. Results: The etiologies of MV disease were rheumatic in 67 and degenerative in 3 cases. The mean duration of AF before sugery was 66$\pm$70 months. Fifteen patients had the past medical history of thromboembolic complications, and left atrial thrombi were identified at operation in 24 patients. Twelve cases were reoperations. Aortic cross clamp (ACC) time was mean 151$\pm$44 minutes, and cardiopulmonary bypass (CPB) time was mean 246$\pm$65 minutes. Concomitant procedures were mitral valve replacement (MVR) in 19, MVR and aortic valve replacement (AVR) in 14, MVR and tricupid annuloplasty (TAP) in 8, MVR with AV repair in 3, MV repair in 11, MVR and coronary artery bypass grafting (CABG) in 2, MVR and AVR and CABG in 1, redo-MVR in 10, redo-MVR and redo-AVR in 2 patients. The rate of hospital mortality was 1.4%(1/70). Perioperative recurrence of AF was seen in 44(62.9%), and atrial tachyarrhythmias in 10(14.3%), low cardiac output syndrome in 4(5.7%), postoperative bleeding that required mediastinal exploration in 4(5.7%) patients. Other complications were acute renal failure in 2, aggravation of preoperative hemiplegia in 1, and transient delirium in 1 patient. We followed up all the survivors for 16.4 months(3-44months) on an average. Sinus rhythm has been restored in 65(94.2%) patients. AF has been controlled by operation alone in 73.9% and operation plus medication in 20.3%. Two patients needed permanent pacemaker implantation; one with sick sinus syndrome, and the other with tachycardia- bradycardia syndrome. Only two patients remained in AF. We followed up our patients with transthoracic echocardiography to assess the atrial contractilities and other cardiac functions. Right atrial contractility could be demonstrated in 92% and left atrial contractility in 53%.We compared our non-redo cases with redo cases. Although the duration of AF was significantly longer in redo cases, there was no differences in ACC time, CPB time, postoperative bleeding amount and sinus conversion rate. Conclusions: In conclusion, the CMP concomitant with MV operation demonstrated a high sinus conversion rate under the acceptable operative risk even in case of reoperation.

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Immunogenicity and Safety of a Haemophilus influenzae Type b Polysaccharide-Tetanus Toxoid Conjugate Vaccine (PRP-T: HiberixTM) in Korean Infants (우리나라 영아에서 PRP-T(HiberixTM)백신의 면역원성 및 안전성에 대한 연구)

  • Chung, Eun Hee;Kim, Yae Jean;Kim, Yun Kyung;Kim, Dong Ho;Seo, Jeong Wan;Lee, Hoan Jong
    • Pediatric Infection and Vaccine
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    • v.10 no.1
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    • pp.71-80
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    • 2003
  • Purpose : Four kinds of Haemophilus influenzae type b protein conjugate vaccines, PRPD, PRP-T, PRP-OMP and PRP-CRM197, have been developed, and PRP-T vaccines are currently produced by two manufacturer, $ActHib^{(R)}$ by Aventis and $Hiberix^{TM}$ by GlaxoSmith-Kline Biologicals. The purpose of this study is to evaluate the immunogenicity and safety of $Hiberix^{TM}$ in Korean infants. Methods : Seventy-three healthy infants(43 male infants) were recruited for this study after parental informed consent was obtained. Each infant was vaccinated at 2, 4 and 6 months of age with the study vaccine. At each visit, infants were also immunized with DTaP, trivalent oral polio vaccine and hepatitis B vaccine when indicated. The serum anti-PRP antibody was measured at prevaccination, 2 month later after the 2nd dose, and 1 month later after the 3rd dose by the ELISA method. The local and systemic adverse reactions of vaccination were monitored for 3 consecutive days after each immunization. Immunogenicity of vaccine was evaluated in infants who received all the scheduled immunization and the adverse reactions were evaluated for infants who received at least one dose of the study vaccine. Results : Among seventy three infants, enrolled in this study; sixty three(37 male infants) completed all the scheduled immunizations. The geometric mean titer(GMT) of anti-PRP antibodies at prevaccination was 0.17 ${\mu}g/mL$(95% confidence interval[CI]; 0.13~0.22). The GMT of anti-PRP antibodies increased to 4.14 ${\mu}g/mL$(95% CI; 2.65~6.48) at 2 month later after the 2nd dose of PRP-T and 14.65 ${\mu}g/mL$(95% CI; 10.83~19.81) at 1 month later after the 3rd dose. Anti-PRP antibody ${\geq}0.15$ ${\mu}g/mL$, was observed in 98.4%(95% CI; 91.8~100) after 2 doses and 100%(95% CI; 100~100) after 3 doses. Anti-PRP antibody ${\geq}1.0$ ${\mu}g/mL$, was obtained in 77.8%(95% CI; 67.5~88.0) after 2 doses, and 98.4%(95% CI; 95.3~100) after 3 doses. Most of the adverse reaction after vaccination were mild. Irritability, the most common systemic reaction, was observed in 45.5%, followed by drowsiness(30.5%), poor feeding(26.7%) and fever(5.6%). Among the local reactions tenderness was observed in 7.9%, redness(${\geq}5$ mm) in 2.8% and swelling(${\geq}5$ mm) in 1.8%. Conclusion : The PRP-T vaccine used in this study was highly immunogenic and safe in Korean young infants. The finding that high GMT and high frequency of infants with a protective titer achieved after 2 doses is consistent with the previous studies which were done with a PRP-T vaccine of other manufacturer. This study suggests that the immunization schedule of PRP-T vaccine for Korean infants may need re-evaluation.

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Characteristics of Particulate Carbon in the Ambient Air in the Korean Peninsula (한반도 권역별 대기 중 입자상 탄소 특성 연구)

  • Lee, Yeong-jae;Park, Mi-kyung;Jung, Sun-a;Kim, Sun-jung;Jo, Mi-ra;Song, In-ho;Lyu, Young-sook;Lim, Yong-jae;Kim, Jung-hoon;Jung, Hae-jin;Lee, Sang-uk;Choi, Won-Jun;Ahn, Joon-young;Lee, Min-hee;Kang, Hyun-jung;Park, Seung-myeong;Seo, Seok-jun;Jung, Dong-hee;Hyun, Joo-kyeong;Park, Jong-sung;Hwang, Tae-kyung;Hong, You-deog;Hong, Ji-hyung;Shin, Hye-jung
    • Journal of Korean Society for Atmospheric Environment
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    • v.31 no.4
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    • pp.330-344
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    • 2015
  • Semi-continuous measurements of $PM_{2.5}$ mass, organic and elemental carbon were made for the period of January to October 2014, at six national air monitoring stations in Korea. OC and EC concentrations showed a clear seasonal variation with the highest in winter (January) and the lowest in summer (August). In winter, the high carbonaceous concentrations were likely influenced by increased fuel combustion from residential heating. OC and EC concentrations varied by monitoring stations with 5.9 and $1.7{\mu}g/m^3$ in Joongbu area, 4.2 and $1.2{\mu}g/m^3$ in Honam area, 4.0 and $1.3{\mu}g/m^3$ in Yeongnam area, 3.7 and $1.6{\mu}g/m^3$ in Seoul Metropolitan area, 3.0 and $0.8{\mu}g/m^3$ in Jeju Island, 2.9 and $0.7{\mu}g/m^3$ in Baengnyeong Island respectively. The concentrations of OC and EC comprised 9.6~ 15.5% and 2.4~ 4.7% of $PM_{2.5}$. Urban Joongbu area located adjacent to the intersection of several main roads showed the highest carbon concentration among six national air monitoring station. On the other hand, background Baengnyeong Island showed the lowest carbon concentration and the highest OC/EC ratio (4.5). During the haze episode, OC and EC were enhanced with increase in $PM_{2.5}$ about 1.3~ 3 and 1.3~ 4.0 times respectively. The concentrations of OC, EC in the Asian dust case are about 1~ 2.4 times greater than in the nondust case. The origins of air mass pathways arriving at Seoul, using the backward trajectory analysis, can be mostly classified into 6 groups (Sector I Northern Korea including the sea of Okhotsk, Sector II Northern China including Mongolia, Sector III Southern China, Sector IV South Pacific area, Sector V Japan, Sector VI Southern Korea area). When an air mass originating from northern China and Mongolia, the OC concentrations were the most elevated, with a higher OC/EC ratio (2.4~ 3.3), and accounting for 17% of $PM_{2.5}$ mass on average.

Analysis of Perception of School Foodservice Facilities and Utilities in Gyeongnam Area by School Nutrition Teachers (Dietitians) -Comparison of School Foodservice Facilities and Improvement of Utilities in Schools- (경남지역 영양(교)사의 급식시설 설비에 대한 인지도 분석 -학교급식시설 현대화 사업 완료 학교와 미완료 학교의 비교를 중심으로-)

  • Jeon, Young;Kim, Hyun-Ah
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.9
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    • pp.1447-1456
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    • 2014
  • The purpose of this study was to compare perception of school foodservice facilities and utilities in dietitians and school nutrition teachers in the Gyeongnam area between schools that improved foodservice facilities and utilities versus those who did not. From July 23 to Aug 31, 2012, 391 questionnaires were distributed, and 289 questionnaires were obtained. A total of 275 questionnaires were used for the final analysis, excluding improper ones. The results of this study were as follows. First, among 275 schools, 90 schools (32.7%) improved school foodservice facilities and utilities while 175 schools (67.3%) did not. Second, schools with improved facilities had a more well-equipped receiving room (P<0.01), preparation room (P<0.001), dishwashing room (P<0.001), storage room for supplies (P<0.001), rest-room for school foodservice employees (P<0.05), locker room (P<0.01), shower room (P<0.001), laundry room (P<0.001), boiler room (P<0.05), and room for serving cart (P<0.05) than schools with no improvement. Third, total perception score of school foodservice facilities area from schools with improved facilities (1.71) was significantly higher than that (1.60) of school without improvement (P<0.001). Fourth, total satisfaction (3.32) of school foodservice facilities and utilities in school with improved facilities was significantly higher than that (2.62) of schools without improvement (P<0.01). Fifth, schools with improved facilities had a better equipped of floor (P<0.05), entrance (P<0.001), drain (P<0.001), water supply (P<0.01), lighting (P<0.001), hand washing (P<0.001), foodservice management room (P<0.001), locker room (P<0.001), rest-room and shower room (P<0.001), and preparation room (P<0.001) than schools without improvement. However, there was no significant difference in terms of walls and ceilings, windows, ventilation, and storage. In conclusion, school foodservice facilities and utilities improvement should conducted as soon as possible.

Training, Working State and Ways of Improving Work of Sex Education Counselors in Health Centers (대구·경북지역 보건소 성교육 담당자의 훈련 및 업무현황과 개선방안)

  • Yeom, Seok-Hun;Kim, Chang-Yoon;Lee, Kyeong-Soo
    • Journal of agricultural medicine and community health
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    • v.27 no.2
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    • pp.159-175
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    • 2002
  • This present study was conducted to reduce problems by analyzing training and work of sex education counselors and to come up with ways of improving sex education counseling. A survey was performed in 57 subjects at health centers who finished training on sex education counseling in Taegu Metropolitan City and cities, kuns, and gus of Kyongsangbuk Province from December, 1999 to February, 2000 on general characteristics, items relating to the work of sex education, and ways of improving work. The results are as follows. Out of the sex education counselors, there were 55 females, taking 99% out of the total counselors, and the average age of these counselors was 42 years. There were 26 nurses, and their government grade was level 7 in 36 and level 6 in 14. The members who had finished sex education counseling at each public health center was 2.1 counselors at an average. Among those had finished sex education training, 30 was not in sex counseling. When analyzed the answers given by 27 sex counselors who were counseling at the time and the results are as follows. As for the amount of work, 15 answered to have too much work and 1 little; as for having pride on being a sex education counselor, 18 answered to felt pride and 7 so-so; as for materials for sex education and counseling, 25 answered to use videos, 23 books, 10 pictures, 8 beam projectors, and 7 slides. All of the subjects answered to have other responsibilities besides sex education and counseling, and the satisfaction felt on having other responsibilities was 6 satisfied, 12 average, and 2 dissatisfied. The proportion of work load in sex education counselors was other work besides sex education 76.2%, sex education at schools 7.6%. collecting sex education materials 5.7%, counseling of adolescents 4.9%. development of sex education materials 3.5%, and administrative work related to sex education 3.1%. The biggest problem of their work was over-load in 9 respondents, lack of sex education materials in 8, lack of training in 6, and shortage of professionals in 2. As for the answer on the ways of improving matters related to work of sex education counselors, the most frequent answer was that the organizations responsible for sex education needs to be more professional and systematic, followed by dividing the work load so that they could concentrate on developing education materials and sex education and counseling. Thus, the results of the present study indicated that in order to utilize human resources efficiently, the speciality of counselors needs to be considered when making personnel transfers among health centers, and continued activity as a sex education counselor needs to promoted by reducing other overloading tasks. And systematic re-training of the counselors needs to be done, and education manuals that are diverse and realistic to applicable to the children, who are to be the subjects of sex education, need to be developed and distributed.

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Actual Conditions and Perception of Safety Accidents by School Foodservice Employees in Chungbuk (충북지역 학교급식 조리종사원의 안전사고 실태 및 인식)

  • Cho, Hyun A;Lee, Young Eun;Park, Eun Hye
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.10
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    • pp.1594-1606
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    • 2014
  • The purpose of this study was to examine safety accidents related to school foodservice, working and operating environments of school foodservice, status and awareness of safety education, educational needs, and information on qualitative improvement of school foodservice. The subjects in this study were 234 cooks in charge of cooking at elementary and secondary schools in Chungbuk. A survey was conducted from July 30 to August 8, 2012, and among 202 questionnaires gathered, 194 completed questionnaires were analyzed. Statistical analyses were performed on data utilizing the SPSS version 19.0. The main results of this study were as follows: 44.3% of workers experienced safety accidents. The most frequent safety accident was 'once' (60.5%), and most safety accidents took place between June and August (31.4%). The time at which most safety accidents happened was between 8 and 11 am. Most safety accidents happened during cooking (52.3%) and while using a soup pot or frying pot (52.4%). The most common accidents were 'burns', 'wrist and arm pain', and 'slips and falls'. Respondents who experienced safety accidents replied that 57.6% of employees dealt with injuries at their own expense, and only 35.3% utilized industrial accident insurance. In terms of the operating environment, the score for 'offering information and application' was highest (3.76 points), whereas that for 'security of budget' was lowest (1.77 points). As for accident education, employees received safety education approximately 3.45 times and 5.10 hours per year. Improving the working environment of school foodservice cooks requires administrative and financial support. Furthermore, educational materials and guidelines based on the working environment and safety accident status of school foodservice cooks are required in order to minimize potential risk factors and control safety accidents in school foodservice.

Effect of Flywheel Weight on Engine Performance for the Small Diesel Engine (Flywheel의 중량(重量)이 소형(小型) 디젤기관(機關)의 성능(性能)에 미치는 영향(影響))

  • Jung, Hae Kook;Kim, Sung Rai;Myung, Byung Soo
    • Korean Journal of Agricultural Science
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    • v.15 no.2
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    • pp.143-152
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    • 1988
  • This study was conducted to obtain basic data which affected engine performance of the power tiller being widely used in the rural area. Among the various factors affected engine performance, only flywheel weight was considered as the major factor in this study. Fuel consumption ratio, motoring loss, torque, vibration and mechanical efficiency of the engine tested were measured and analyzed on the four levels of flywheel weight (32.2, 29.7, 26.4, 24.2 kg). The results obtained were as follows: 1. The maximum output of 6 and 7.5 kW engine was 7.43 kW and 7.85 kW respectively. When flywheel weight was reduced from 32.2 kg to 24.2 kg, output power of the engine was increased 0.27 kW in 6 kW engine and increased 0.39 kW in 7.5 kW engine. 2. The fuel consumption ratio was decreased from 300.8 to 296.8 g/kW-hr in 6 kW engine and decreased from 313.6 to 312.8 g/kW-hr in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 3. The mechanical efficiencies of the engine was increased from 76.1 to 76.8% in 6 kW engine and increased from 76.7 to 77.0% in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 4. When the flywheel weight was reduced from 32.2 kg to 24.2 kg, a tendency of a little decrease of vibration at X- and Z-axis in 6 kW engine and of a little increase of vibration at Y-axis in 6 kW engine and all directions in 7.5 kW engine was observed. 5. Motoring losses was decreased from 2.33 to l.76 kW in 6 kW engine and decreased from 2.46 to 1.84 kW in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. From the above results and the flywheel weight calculated theoretically, it was recommendable that the flywheel weight should be reduced about 7 kg in 6 kW engine and about 10 kg in 7.5 kW engine, respectively.

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