• Health Policy and Management
• /
• v.2 no.1
• /
• pp.42-65
• /
• 1992

To survey the specialties or sujects of practice displayed by the private practitioners the authors visited 691 clinics in Taegu from April 1 to May 18, 1991, At the same time, a mail questionnaire was administered to ask the number of displayed subjects of practice, and the reasons for displaying the subjects, reasons for not displaying in case of no specialty was displayed, composition of patients, and role as a specialist. The questionnaire was returned by 308(44.6%) practitioners. The distributions of private practitioners by specialty were 13.9% for internal medicine (IM), 11.7% for pediatrics(Ped), 13.0% for obstetrics '||'&'||' gynecology(OBGY), 11.1% for general surgery(GS), 10.0% for family practice(FP), and 5.3% for general practitioner(GP). Ninety percent of the specialists have displayed their specialty in their offices. Among all the private practitioners, 61.9% of them have displayed their subjects of practice and 23.7% have shown telephone number. Among private practitioners who displayed the subjects of practice, 80.6% have signs of 'subjects of practice'. Mean number of the displayed subjects of practice for the all private practitioners is 1.20, and 1.93 for the private practitioners who displayed subjects of practice. FP and GS have displayed their subjects of practice in 91.2% and 87.0% respectively and OBGY have displayed in 32.2%, the lowest percentage among all the soecuaktues. IM specialists displays pediatrics as a major subject of practice in 72.1% the pediatricians display IM in 88.9% the OBGYs display pediatrics in 77.8%, and the GSs display IM in 51.9%. Most commonly displayed subjects of practice are Ped and IM. Sixty-five percent of the private practitioners answered that they don't display their specialties because their clinics are "primary health care facility". The reasons for displaying the subjects of practice and its relevance with their own specialty(45.6%), and the difficulty in clinic management only with the patients for their own specialty(36.9%). The proportion of clinics whose patients of other specialty are than their own specialty accounted less than 10% was 52.8% and that accounted more than 51% was 16.0%. Specially, 51.4% of GS specialists cared more than 51% of patients of other specialty area than their own specialty. Most of the patients of IM, Ped, and OBGY specialists are the patients of their own specialty. However, 56.8% of GS care more of IM patients and only 24.3% of them care mostly GS patients, The respondents to the mail questionnaire who stated that they can not play the role of specialist well are 30.5% and especially 72.9% of the GS specialists state so. The proportion of respondents who do not suffort the private practice of specialists is 71.1%. Among the surgical specialists, 82.7% of them rarely perform operation. The reasons for not performing operation are insufficient insurance fee (76.9%), and risk of operation(58.0%), so as the OBGY specialists. Above finidngs suggest that most of the specialists, especially surgeons, in the private practice can not play their role as a specialist. It is necessary to develop a policy that facilitates the production of practice and the retention of the specialists in the hospitals.s.

• Journal of Institute of Control, Robotics and Systems
• /
• v.7 no.9
• /
• pp.717-722
• /
• 2001

This paper presents a methodology on the backward path tracking control of a trailer type robot which consists of two parts: a tractor and a trailer. It is difficult to control the motion of a trailer vehicle since its dynamics is non-holonomic. Therefore, in this paper, the modeling and parameter estimation of the system using a real-coded genetic algorithm(RCGA) is proposed and a backward path tracking control algorithm is then obtained based on the linearized model. Experimental results verify the effectiveness of the proposed method.

• Journal of radiological science and technology
• /
• v.36 no.4
• /
• pp.313-318
• /
• 2013

Positron emission tomography/computed tomography (PET/CT) imaging with fluorodeoxyglucose (FDG) have been used as a powerful fusion modality in nuclear medicine not only for detecting cancer but also for staging and therapy monitoring. Nevertheless, there are various causes of FDG uptake in normal and/or benign tissues. The purpose of present study was to investigate whether additional delayed imaging can improve the diagnosis to differentiate the rates of FDG uptake at axillary lymph nodes (ALN) between malignant and benign in breast cancer patients. 180 PET/CT images were obtained for 27 patients with ALN uptake. The patients who had radiotherapy and chemotherapy were excluded from the study. $^{18}F$-FDG PET/CT scan at 50 min (early phase) and 90 min (delayed phase) after $^{18}F$-FDG injection were included in this retrospective study. The staging of cancers was confirmed by final clinical according to radiologic follow-up and pathologic findings. The standardized uptake value (SUV) of ALN was measured at the Syngo Acquisition Workplace by Siemens. The 27 patients included 18 malignant and 9 ALN benign groups and the 18 malignant groups were classified into the 3 groups according to number of metastatic ALN in each patient. ALNs were categorized less than or equal 3 as N1, between 4 to 9 as N2 and more than 10 as N3 group. Results are expressed as the mean${\pm}$standard deviation (S.D.) and statistically analyzed by SPSS. As a result, Retention index (RI-SUV max) in metastasis was significantly higher than that in non-metastasis about 5 fold increased. On the other hand, RI-SUV max in N group tended to decrease gradually from N1 to N3. However, we could not prove significance statistically in malignant group with ANOVA. As a consequence, RI-SUV max was good indicator for differentiating ALN positive group from node negative group in breast cancer patients. These results show that dual-time-point scan appears to be useful in distinguishing malignant from benign.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.1 no.1
• /
• pp.103-113
• /
• 1993

Every year, over $3.37{\times}10^7$ ton of municipal solid waste is generated in Korea, of which about 28% is organic food waste from restaurant, dining halls and households etc. Methane conversion of the food waste by anaerobic digestion could be a viable approach for energy recovery as well as safe disposal of the waste. However, as food waste is composed of highmolecular complex polymers such as cellulose, lignin and protein, anaerobic digestion of food waste has not been efficient in terms of volumetric loading rate, solid retention time and extent of anaerobic degradation. In this research, the improved anaerobic degradation of food waste was attemped by applying rumen microorganisms to anaerobic digestion. Acidification efficiency of food waste by rumen microorganisms was compared with that of conventional acidogenesis. And optimum acidification conditions by rumen microorganisms were also determined. For the experiments, anaerobic batch reactors of 600 mL was fed with the processed (dried and milled) food waste obtained from a restaurant. Ultimate volatile fatty acid (VFA) yield produced by rumen microorganisms was about 8.4 meq VFA/g volatile solid (VS) that is 95% of the theoretical value. This yield was not much different from that of conventional acidogenesis, but hydrolysis rate was about twice faster. Cumulative VFA concentration increased from 66 meq/L to 480 meq/L, when the initial TS was increased from 1% to 15%. But VFA yield at 15% TS was half of that at 1% TS. This inhibition on the acidification might be caused by the rapid drop of pH and higher concentration of nonionized VFA. Optimal pH and temperature range for the acidification were about 6.0~7.5 and $35{\sim}45^{\circ}C$, respectively.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.4
• /
• pp.223-231
• /
• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• Journal of Intelligence and Information Systems
• /
• v.21 no.2
• /
• pp.19-47
• /
• 2015

In this era of knowledge economy, a variety of virtual communities are proliferating for the purpose of knowledge creation and utilization. Since the voluntary contributions of members are the essential source of knowledge, member turnover can have significant implications on the survival and success of virtual communities. However, there is a dearth of research on the effect of membership turnover and even the method of measurement for membership turnover is left unclear in virtual communities. In a traditional context, membership turnover is calculated as the ratio of the number of departing members to the average number of members for a given time period. In virtual communities, while the influx of newcomers can be clearly measured, the magnitude of departure is elusive since explicit withdrawals are seldom executed. In addition, there doesn't exist a common way to determine the average number of community members who return and contribute intermittently at will. This study initially examines the limitations in applying the concept of traditional turnover to virtual communities, and proposes five membership fluidity measures based on a preliminary analysis of editing behaviors of 2,978 featured articles in English Wikipedia. Subsequently, this work investigates the relationships between three selected membership fluidity measures and group collaboration performance, reflecting a moderating effect dependent on work characteristic. We obtained the following results: First, membership turnover relates to collaboration efficiency in a right-shortened U-shaped manner, with a moderating effect from work characteristic; given the same turnover rate, the promotion likelihood for a more professional task is lower than that for a less professional task, and the likelihood difference diminishes as the turnover rate increases. Second, contribution period relates to collaboration efficiency in a left-shortened U-shaped manner, with a moderating effect from work characteristic; the marginal performance change per unit change of contribution period is greater for a less professional task. Third, the number of new participants per month relates to collaboration efficiency in a left-shortened reversed U-shaped manner, for which the moderating effect from work characteristic appears to be insignificant.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.1
• /
• pp.23-32
• /
• 2010

The capacity of natural purification was limited by the interruption of natural flow and the problems such as eutrophication were occurred by nutritive salts accumulation in stagnant stream. Moreover, the inflow of non-point sources causes non-degradable materials to increase in stagnant stream. In this study, an upflow biological activated carbon (BAC) biofilm process comprised of anoxic, aerobic 1, and aerobic 2 reactors were introduced for treatment of stagnant stream and SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP were monitored in the upflow BAC biofilm reactors with continuous cycling. In order to simulate stagnant stream, the lake water of amusement park and golf course were stored as influent in a tank of $2m^3$ and hydraulic retention time (HRT) was changed into 6, 4, and 2 hours. At HRT 4hr and the lake water of amusement park as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP showed the best water quality improvement and were 69.8, 83.0, 91.3, 74.1, 74.7, and 88.9%, respectively. At HRT 4hr and the lake water of golf course as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN and TP were 78.5, 78.0, 80.2, 74.9, 55.6 and 97.5%, respectively. As the results of polymerase chain reaction - denaturing gel gradient electrophoresis (PCR-DGGE), microbial community was different depending on influent type. Fluorescence in situ hybridization (FISH) showed that nitrifying bacteria was dominant at HRT 4 hr. The biomass amount and microbial activities by INT-DHA test were not decrease even at lower HRT condition. In this study, the upflow BAC biofilm process would be considered to the water quality improvement of stagnant stream.

• Korean Journal of Microbiology
• /
• v.51 no.4
• /
• pp.355-363
• /
• 2015

The present work quantified the growth of young biofilm in a model distribution system that was fed with chlorinated drinking water at a hydraulic retention time of 2 h. Bacterial biofilms grew on the surface of polyvinyl chloride (PVC) slides at a specific growth rate of $0.14{\pm}0.09day^{-1}$ for total bacteria and $0.16{\pm}0.08day^{-1}$ for heterotrophic bacteria, reaching $3.1{\times}10^4cells/cm^2$ and $6.6{\times}10^3CFU/cm^2$ after 10 days, respectively. The specific growth rates of biofilm-forming bacteria were found to be much higher than those of bulk-phase bacteria, suggesting that biofilm bacteria account for a major part of the bacterial production in this model system. Biofilm isolates exhibited characteristic kinetic properties, as determined by ${\mu}_{max}$ and $K_S$ values using the Monod model, in a defined growth medium containing various amounts of acetate. The lowest ${\mu}_{max}$ value was observed in bacterial species belonging to the genus Methylobacterium, and their slow growth seemed to confer high resistance to chlorine treatment (0.5 mg/L for 10 min). $K_S$ values (inversely related to substrate affinity) of Sphingomonas were two orders of magnitude lower for acetate carbon than those of other isolates. The Sphingomonas isolates may have obligate-oligotrophic characteristics, since the lower $K_S$ values allow them to thrive under nutrient-deficient conditions. These results provide a better understanding and control of multi-species bacterial biofilms that develop within days in a drinking water distribution system.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.11
• /
• pp.1554-1558
• /
• 2012

Method development and validation of ellagic acid for the standardization of Gochang Bokbunja as a functional ingredient and health food were accomplished. A Symmetry$^{(R)}$ (C18, $4.6{\times}250mm$, $5.0{\mu}m$) column was used with a gradient elution system of 1% formic acid in water and acetonitrile. This method was validated according to specificity, linearity, accuracy, precision test, and recovery test. Specificity was confirmed with identical retention time, and calibration curves of ellagic acid showed good linear regression ($R^2$ >0.9996). Relative standard deviations (RSD) of data from the intra- and inter-day experiments were less than 2.28% and 2.84%, except in the low limit of quality control (LLOQ, $1{\mu}g/mL$) sample. The results of the recovery test were from 89.17% to 97.92% with RSD values from 0.05 to 0.14%. Therefore, we performed analysis of ellagic acid as a marker compound in Gochang Bokbunja extracts. The amount of ellagic acid in Gochang Bukbunja was about $1.918{\mu}g/mg$ (0.192%) in the three times analysis, and RSD was less than 2.36% by the validated method. These results suggest that the developed HPLC method is simple, efficient, and could contribute to the quality control of Gochang Bokbunja extract as a functional ingredient.

• Korean Journal of Weed Science
• /
• v.30 no.4
• /
• pp.361-370
• /
• 2010

This study was carried out to establish the analytical method of MCPA residue in brown rice and rice straw by HPLC/UVD. When MCPA was extracted from sample under the pH 3.6 by adding acetone 200 mL and 1N-HCl 100 mL, the extraction efficiency was high by 87%. And purification efficiency was high by 83% when 5 mL of 1% methanol/acetonitrile was eluated by the florisil Sep-pak cartridge column. From spiking of $0.1{\mu}g\;mL^{-1}$ and $0.25{\mu}g\;mL^{-1}$ of MCPA to control sample, respectively, average recovery rate of MCPA in brown rice was 96.0% and 94.9% and that in rice straw was 92.5% and 88.2%, respectively. Precision of experiment was very high by relative standard deviation of 1.5% to 5.7%. In brown rice and rice straw treated with bentazone+MCPA (11+1.2%) of 30 kg and 60 kg per ha at 30 days after rice transplanting, respectively, maximum residue limit was under $0.05{\mu}g\;mL^{-1}$ of the recommended rate of Korean Food and Drug Administration. From the above results, the analytical procedure of MCPA in plants such as hydrolysis, saponification and derivatization were ommited, and retention time was faster and recovery rate was higher than the existed results of HPLC/UVD. Therefore, these results were greatly improved and seemed to be usefully applied for residue analysis of MCPA in plants.