• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.397-405
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• 2003

Heat and fluid flow in a compressor into which liquid refrigerant is injected for the purpose of reducing discharge gas temperature in a heat pump system has been numerically studied. A mechanistic approach encompassing liquid jet breakup and droplet evaporation has been performed to investigate the effects of liquid injection on the spacial and temporal variation of the gas temperature and pressure inside the compressor cylinder. Various parameters, such as liquid injection mass, time, duration and droplet size, are considered in the present study to elucidate the flow field inside the compressor. As the injection mass is increased, discharge gas temperature is decreased, while the pressure is increased due to the added mass of the injection. For the injected liquid mass corresponding to 15% of the total vapor mass in the cylinder, the discharge gas temperature drops by 22.4 K. It is observed that the droplet size plays a major role in the evaporation rate of the droplets that determines the degree of the discharge temperature drop.

• Journal of Information Display
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• v.2 no.2
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• pp.39-44
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• 2001

The conditions of the wall charges and priming particles in a unit discharge cell in AC PDP seriously affect the addressing discharge characteristics in the driving method with ramped setup pulse. Moreover, the discharge conditions at the end of the scan line may be different from the first scan line because of the difference of about 1ms address time. Consequently, the addressing time and its dispersion may be different for any two discharge cells that lead to misfiring and the increase in the total addressing time. In order to improve the addressing time and its dispersion, we have applied different addressing voltage at each cell such as progressively increase pulse voltage instead of constant one. As a result, the addressing time and its dispersion of all cells were improved by about 30% compared with the conventional driving method.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.37-46
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• 2012

This study was conducted to identify groundwater recharge and discharge amounts of a representative urban-rural composite area located in Yongin city, Kyounggi-do, Korea. Groundwater recharge would be affected by mainly two processes in the study area: rainfall and leakage from public water pipelines including water-supply and sewage system. Groundwater recharge rate was estimated to be 13.5% by applying annual groundwater level data from two National Groundwater Monitoring Stations to the master regression curve method. Subsequently, the recharge amounts were determined to be $13,253{\times}10^3m^3/yr$. Leakage amounts from water-supply and sewage system were estimated to be $3,218{\times}10^3$ and $5,696{\times}10^3m^3/yr$, respectively. On the whole, a total of the recharge amounts was $22,167{\times}10^3m^3/yr$, of which 60% covers rainfall recharge and 40% pipeline leakage. Groundwater discharge occurred through three processes in the composite area: baseflow, well pumping, and discharge from urban infrastructure including groundwater infiltration into sewage pipeline and artificial extraction of groundwater to protect underground facilities from submergence. Discharge amounts by baseflow flowing to the Kiheung agricultural reservoir and well pumping were estimated to be $382{\times}10^3$ and $1,323{\times}10^3m^3/yr$, respectively. Occurrence of groundwater infiltration into sewage pipeline was rarely identified. Groundwater extraction amounts from the Bundang subway line as an underground facility were identified as $714{\times}10^3m^3/yr$. Overall, a total of the discharge amounts was determined to be $2,419{\times}10^3m^3/yr$, which was contributed by 29% of artificial discharge. Even though groundwater budget of the composite area was identified to be a surplus, it should be managed for a sound groundwater environment by changing deteriorated pipelines and controlling artificial discharge amounts.

• Quality Improvement in Health Care
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• v.8 no.2
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• pp.208-217
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• 2001

Background : The objective of this study is proving the basic data for developing a management system for the discharges against medical advice(AMA) by identifying the characteristics of the AMA patients of an university hospital for 10 years. Methods : By using discharge abstract data base, we divided the total discharges(435,254) into two groups, discharge against medical advice and discharge with discharge order. We confirmed the characteristics of AMA group by analyzing discharge abstract data of the both groups by SAS software V6.12 and $x^2$ test. Medical records of AMA patients in the year 2000 were reviewed to identify the reasons for AMA which we couldn't extract from discharge abstract DB. Result : The total number of AMA for 10 years were 9,358(2.15%) and the AMA rate has been continuously decreased for 10 years. Male, admission through emergency room, discharges admission via other hospital, patients without operation during hospitalization, discharges in hopeless or not improved condition showed higher AMA rate. The AMA rate was higher as the age of the patients was higher, and the average length of stay was longer in AMA patients than in those with discharge order. The AMA rate in psychiatry was highest(14.3%) and it was higher in surgery departments than those of medical or other sections. The AMA rate varied by attending physicians even in the same department and it was statistically significant. Patients with the principal diagnosis of "medical observation and evaluation for suspected diseases" showed the highest AMA rate(15.5%), and that of schizophrenia or psychosis was the nest. One hundred twenty-one patients(19.5%) out of 622 AMA in 2000 discharged against medical advice for transfer to order health care facilities. Among them 71 patients(58.7%) discharged with their medical care information, such as copies of medical record, medical certificates, summaries, etc. Written oath of the patients discharged AMA was filed in their medical records in 466 cases(74.9%) although some of them were incomplete. Conclusion : Characteristics of AMA discharge could be used as the basic data in developing a system to manage the patients who have risk factors to leave the hospital against medical advice. By reducing number of patients leaving the hospital against medical advice we can increase satisfaction of medical providers and consumers.

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.8 no.1
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• pp.50-61
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• 2001

With the improvement of current medicine, the number of the chronicly ill children are increasing. The illness of the child drives all of the family to despair. especially it is a burden on the mother who takes care of the ill child. She's faced with many emergencies and feels powerless. The home care for a child is for finding a child's problems early and mediating them. The purpose of this study was to investigate the mother's reaction following their chronicly ill child's discharge and to investigate the supporting needs for caring for an ill child. The subjects of this study were mothers with a chronicly ill child being discharged from a general hospital in Seoul and the data was collected from July 20 to September 30. Data was collected by using questionnaires which were developed by the researcher. (The questionnaires were composed of the average 5 points - Likert's method). The Mother's reaction means that the higher the score, the more negative the mother's thoughts about discharge are. Supporting need for caring for ill an child means that the higher the score, the higher the demand of nursing is. The statistical analysis used the SPSS program for t-test. ANOVA, and Pearson Correlation. The results of this study were as follows: 1. The mother's reaction scores following discharge were the lowest. 19 and the highest 72 so that the total average was 43.15. The answer, 'I worry that my baby will be troubled with illness again after discharge gained the high points (3.94 of 5 points). The answer. 'The discharge of my baby makes me gloomy' gained 2.05-it was the lowest points. Their were significant differences according to religion (p=.006). salary (p=.050). the burden of the medical fee (p = .005) and caregiver (p=.027). 2. Supporting Need for caring for ill an child was the lowest 15 and the highest 67. the total average was 47.87. The answer. 'I'd be glad to get a person whom I could always get counsel about the health of my baby with' scored the high point (average 4.04 of 5). The answer. 'Caring for my baby at home makes me exhausted' gained the lowest point. 2.49. Their were significant differences according to religion (p=.019) and diagnosis (p=.019). 3. The relationship between the reaction of the mother and supporting need for caring for an ill child was a positive correlation (r=0.585). In conclusion. this study revealed that mothers weren't positive about their chronicly ill child's discharge and they wanted to get support for caring for an ill child. Through this study. I proposed that the program to support the chronicly ill child at home and home care by continuous counselling after discharge should be develop.

• Korea Journal of Hospital Management
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• v.10 no.2
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• pp.64-80
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• 2005

The objectives of this study were to identify factors associated with unexpected revisit to an emergency medical center (EMC) located in Seoul and to examine reasons for revisit. During March, June, September and December, 2002, a total of 168 patients had unexpected revisits to the EMC within 48 hours of a previous discharge. As a 1:1 matched control, we included 136 patients who: discharged from the EMC during the same time period: did not return to the EMC; had the same diagnosis and age(${\pm}5$) with the case. In this study, factors associated with unexpected revisits were defined as characteristics of a previous discharge, which were classified into three: sociodemographic, EMC visit-related, and discharge management factors. Reasons for revisit were categorized into disease, physician, patients, and system-related factors. Data were collected by medical chart review with assistance from clinicians of the EMC. Logistic regression results showed that patients who headed home after discharge without follow-up schedule had a 27.6 times higher risk of revisiting EMC than those who were hospitalized following EMC visit. Patients discharged on his own will had a 5.9 times higher risk of revisiting than those discharged following physician's advice. Patients requiring continual observation at the time of discharge were more likely to revisit by 8.7 times than those discharged with improved condition. About 69.13% of the revisits were due to disease-related factors, followed by 13.90% due to patient-related factors, 8.64% due to system-related factors, and 8.34% due to physician-related factors. It appears that the most significant factors influencing revisits are discharge management factors such as patient's condition at discharge, whether the discharge was accorded with physician's advice, and whether returning home without follow-up schedule. Therefore, appropriate discharge management is necessary to prevent EMC revisit.

• Environmental Engineering Research
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• v.19 no.3
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• pp.197-203
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• 2014

This study estimated spatial and seasonal variation of water quality to understand characteristics of Nakdong river basin, Korea. All together 11 parameters (discharge, water temperature, dissolved oxygen, 5-day biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, electrical conductivity, total nitrogen, total phosphorus, and total organic carbon) at 22 different sites for the period of 2003-2011 were analyzed using multivariate statistical techniques (cluster analysis, principal component analysis and factor analysis). Hierarchical cluster analysis grouped whole river basin into three zones, i.e., relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) based on similarity of water quality characteristics. The results of factor analysis/principal component analysis explained up to 83.0%, 81.7% and 82.7% of total variance in water quality data of LP, MP, and HP zones, respectively. The rotated components of PCA obtained from factor analysis indicate that the parameters responsible for water quality variations were mainly related to discharge and total pollution loads (non-point pollution source) in LP, MP and HP areas; organic and nutrient pollution in LP and HP zones; and temperature, DO and TN in LP zone. This study demonstrates the usefulness of multivariate statistical techniques for analysis and interpretation of multi-parameter, multi-location and multi-year data sets.

• Water for future
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• v.29 no.4
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• pp.233-234
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• 1996

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.11-18
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• 2015

PURPOSES: This study aims to evaluate the runoff reduction with permeable pavements using the SWMM analysis. METHODS: In this study, simulations were carried out using two different models, simple and complex, to evaluate the runoff reduction when an impermeable pavement is replaced with a permeable pavement. In the simple model, the target area for the analysis was grouped into four areas by the land use characteristics, using the statistical database. In the complex model, simulation was performed based on the data on the sewer and road network configuration of Yongsan-Gu Bogwang-Dong in Seoul, using the ArcGIS software. A scenario was created to investigate the hydro-performance of the permeable pavement based on the return period, runoff coefficient, and the area of permeable pavement that could be laid within one hour after rainfall. RESULTS : The simple modeling analysis results showed that, when an impervious pavement is replaced with a permeable pavement, the peak discharge reduced from $16.7m^3/s$ to $10.4m^3/s$. This represents a reduction of approximately 37.6%. The peak discharge from the whole basin showed a reduction of approximately 11.0%, and the quantity decreased from $52.9m^3/s$ to $47.2m^3/s$. The total flowoff reduced from $43,261m^3$ to $38,551m^3$, i.e., by approximately 10.9%. In the complex model, performed using the ArcGIS interpretation with fewer permeable pavements applicable, the return period and the runoff coefficient increased, and the total flowoff and peak discharge also increased. When the return period was set to 20 years, and a runoff coefficient of 0.05 was applied to all the roads, the total outflow reduced by $5195.7m^3$, and the ratio reduced to 11.7%. When the return period was increased from 20 years to 30 and 100 years, the total outflow reduction decreased from 11.7% to 8.0% and 5.1%, respectively. When a runoff coefficient of 0.5 was applied to all the roads under the return period of 20 years, the total outflow reduction was 10.8%; when the return period was increased to 30 and 100 years, the total outflow reduction decreased to 6.5% and 2.9%, respectively. However, unlike in the simple model, for all the cases in the complex model, the peak discharge reductions were less than 1%. CONCLUSIONS : Being one of the techniques for water circulation and runoff reduction, a high reduction for the small return period rainfall event of penetration was obtained by applying permeable pavements instead of impermeable pavement. With the SWMM analysis results, it was proved that changing to permeable pavement is one of the ways to effectively provide water circulation to various green infrastructure projects, and for stormwater management in urban watersheds.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.1
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• pp.1394-1408
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• 1968

The tidal discharge is defined as the quantity of water flowing through a certain cross-section per unit of time, in contrast to river discharges, tidal discharges change periodically in magnitude and direction. Thus the total volumes of water flowing into again out of the system-called flood volume and ebb volume, respectively, depend on both the tidal and the river discharges. To ditermine the tidal discharge and the flood and ebb volumes of the Yong-san river, the discharges were measured at spring, mean and neap tide and simultaneous gage reading were taken at Samhak-do, Lower Myo-do, Myongsan-ni and Naju. The general procedure for measuring the tidal discharges was as follows. First, several cross-sections were measured and one of them was chosen. First, several cross-sections were measured and one of them was chosen. Then verticals were serected in the chosen cross section. Because comparatively few verticals should be representative of the discharge distribution over the river profile, the selection was done in accordance with the somtimes irregular bottom profile. The velocities were measured with the same current meters. The observations which included water level readings were continued for a period of about 13 hours. The current direction meter, a pyramid shaped resistance body, suspend in the water on a thin wire. The bubble in a circular tilting level fixed to the wire indicates the direction of the current. Reading were taken at intervals of 1m for depths of 10m or less, and for depths over 10m at intervals of 2m, going downwards and upwards. The averages of the two velocities were used for the computation of the discharges. The discharges and the flood and ebb volumes were ditermined by a graphical method. The mean velocities, corrected for their direction when necesary, were ditermined for each time interval and each vertical, and these velocities were plotted against the time. The resulting curves show possible mistakes very clearly, and the effect of observation errors could be reduced. The corrected velocities read from the curve at half-hour intervals were multiplied by the depth at the virtical at the corresponding time. The discharges thus found were ploted against the position of the vertical in the transit and joined by a smooth curve, integration of the curve rendered the total discharges as they occurred of half-hour intervals. Plotting these total discharges against the time yeilded during the day. The flood and ebb volumes were obtained by integration of the total discharge curve.