• Journal of the Korean Society for Library and Information Science
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• v.55 no.4
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• pp.219-243
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• 2021

This study analyzes the effects of community-level socioeconomic deprivations (SED) on public libraries' book circulation in the Seoul metropolitan area. The study design draws upon the theory of local information landscapes, which explains the relationship between community characteristics and information behavior. Using four-year (2015-2018) open government and public library circulation data, we constructed a socioeconomic deprivation index by adjusting a multi-dimensional deprivation index and generated other variables. Multi-level robust linear regression models were used to examine the relationship between SED and public library circulation. In addition, we tested the moderating effects of the library collection size and the number of libraries per unit area, respectively, on library circulation. The results show that there is a significant negative relationship between socioeconomic deprivation and library circulation rate. Also, we found that the size of the library collection negatively moderates the effects of SED in areas with a large number of books, and the number of libraries per unit area was positvely related to the library book circulation, not moderating the effects of SED. These findings suggest that public libraries and policymakers should consider community characteristics in designing strategic plans for public libraries.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.161-170
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• 2007

A submerged biofilm sequencing batch reactor (SBSBR) process, which liquor was internally circulated through sandfilter, was designed, and performances in swine wastewater treatment was evaluated under a condition of no external carbon source addition. Denitrification of NOx-N with loading rate in vertical and slope type of sandfilter was 19% and 3.8%, respectively, showing approximately 5 times difference, and so vertical type sandfilter was chosen for the combination with SBSBR. When the process was operated under 15 days HRT, 105L/hr.m3 of internal circulation rate and 54g/m3.d of NH4-N loading rate, treatment efficiencies of STOC, NH4-N and TN (as NH4-N plus NOx-N) was 75%, 97% and 85%, respectively. By conducting internal circulation through sandfilter, removal performances of TN were enhanced by 14%, and the elevation of nitrogen removal was mainly attributed to occurrence of denitrification in sandfilter. Also, approximately 57% of phosphorus was removed with the conduction of internal circulation through sandfilter, meanwhile phosphorus concentration in final effluent rather increased when the internal circulation was not performed. Therefore, It was quite sure that the continuous internal circulation of liquor through sandfilter could contribute to enhancement of biological nutrient removal. Under 60g/m3.d of NH4-N loading rate, the NH4-N level in final effluent was relatively low and constant(below 20mg/L) and over 80% of nitrogen removal was maintained in spite of loading rate increase up to 100g/m3.d. However, the treatment efficiency of nitrogen was deteriorated with further increase of loading rate. Based on this result, an optimum loading rate of nitrogen for the process would be 100g/m3.d.

• Journal of Digital Convergence
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• v.11 no.9
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• pp.229-238
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• 2013

Out-of-hospital cardiac arrest is a major public health problem in Korea. The survival rate to discharge remains at approximately 3.5% and only 1% have good neurological function. To increase the survival rate, prehospital care should restore spontaneous circulation. The purpose of this study was to analyze the factors associated with return of spontaneous circulation(ROSC) after out-of-hospital cardiac arrest. Data used for this study were collected from KCDC Out-of-Hospital Cardiac Arrest Surveillance 2009. As for the results of decision tree analysis, it is clear that prehospital CPR, cardiac arrest witness, activity, past history(cancer/heart disease/stroke), place, bystander CPR, response time, age, etc are significant contributing factors in ROSC. Among 16 cardiac arrest types from decision tree classification, the ROSC rate of type 1 is the highest(29.6%). Also notable is the fact that bystander CPR was strongly correlated with ROSC of patents with cardiac arrest occurring in non-public places. Community resources should be concentrated on increasing bystander CPR and early prehospital emergency care.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.185-192
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• 2010

The chemical-looping combustion(CLC) has advantages of no energy loss for separation of $CO_2$ without $NO_x$ formation. This CLC system consists of oxidation and reduction reactors where metal oxides particles are circulating through these two reactors. In the present study, the reaction kinetic equations of iron oxide oxygen carriers supported on bentonite have been determined by the shrinking core model. Based on the reactivity data, design values of solid circulation rate and solids inventory were determined for the rector. Two types of interconnected fluidized bed systems were designed for CLC application, one system consists of a riser and a bubbling fluidized bed, and the other one has a riser and two bubbling fluidized beds. Solid circulation rates were varied to about $30kg/m^2s$ by aeration into a loop-seal. Solid circulation rate increases with increasing aeration velocity and it increases further with an auxiliary gas flow into the loop-seal. As solid circulation rate is increased, solid hold up in the riser increases. A typical gas leakage from the riser to the fluidized bed is found to be less than 1%.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.726-731
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• 2001

A thermal design software is developed for the heat recovery steam generator(HRSG) of combined cogeneration systems. The heat transfer is calculated by using the element method to account for the varying thermal properties across the heat transfer elements. The circulation balance is computed for the evaporator to accurately estimate the steam generation rate and to check the proper circulation of the boiler water through the tubes. The software developed can be used to simulate HRSG systems with various combinations of auxiliary burner, wall superheater, superheater, reheater, evaporator, and economizer. Systems with several different combinations of the system components are successfully tested. And it is concluded that the developed software can be used for the design of heat recovery steam generators with various combinations of heat transfer components.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.81-86
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• 2006

High temperature superconducting (HTS) power cable requires forced sub-cooled LN2 flow cooling. Liquid nitrogen is circulated by a pump and cooled back by cooling system. Typical operating temperature range is expected to be between 65 K and 77 K. The HTS power cable needs sufficient cooling to overcome its low temperature heat load. For successful cooling, the hydraulic characteristics of the HTS power cable must be well investigated to design the cables. Especially, the pressure drop in the cable is an important design parameter, because the pressure drop decides the length of the cable, size of the coolant circulation pump and circulation pressure, etc. This paper describes measurement and investigation of the pressure drop of the cooling system. In order to reduce the total pressure drop of the cooling system, the flow rate of liquid nitrogen must be controlled by rotational speed of the circulation pump.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.403-411
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• 1995

The atmospheric responses to a Sea Surface Temperature Anomaly(SSTA) over the equatorial eastern Pacific Ocean have been investigated using the horizontally fine resolution model based on OSU 2-layer Atmospheric General Circulation Model(AGCM). The SSTAS daring the peak phase of 1982-83 El Nino have been applied to the model as the boundary conditions of the experiment. The model simulates the eastward movement of the rising branch of the Walker circulation. That is, the major features associated with the El Nino such as the increase of the precipitation rate over the center of the Pacific and decrease over the Indonesia, and the 500hPa geopotential height anomaly in the middle latitude are properly describes in the fine resolution model experiment. The model results indicate that this horizontally fine resolution UM can successfully simulate the ENSO anomalies and be more effectivelly used for the study of the climate and the climate changes.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.103-112
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• 2017

Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

• Journal of Information Processing Systems
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• v.17 no.6
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• pp.1179-1190
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• 2021

A data acquisition and monitoring system was developed for an automated system of a smart fish farm. The fish farm is located in Jang Hang, South Korea, and was designed as circulation filtration system. Information of every aquaculture pool was automatically measured by pH sensors, dissolved oxygen sensors, and water temperature sensors and the data were stored in the database in a remoted server. Modbus protocol was used for gathering the data which were further used to optimize the pool water quality to predict the rate of growth and death of fish, and to deliver food automatically as planned by the fish farmer. By using JSON protocol, the collected data was delivered to the user's PC and mobile phone for analysis and easy monitoring. The developed monitoring system allowed the fish farmers to improve fish productivity and maximize profits.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1125-1139
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• 2023

The system-integrated modular advanced reactor 100 (SMART100), an integral-type pressurized water small modular reactor, is based on a novel design concept for containment cooling and radioactive material reduction; it is known as the containment pressure and radioactivity suppression system (CPRSS). There is a passive cooling system using a condensation with non-condensable gas in the SMART CPRSS. When a design basis accident such as a small break loss of coolant accident (SBLOCA) occurs, the pressurized low containment area (LCA) of the SMART CPRSS leads to steam condensation in an incontainment refuelling water storage tank (IRWST). Additionally, the steam and non-condensable gas mixture passes through the CPRSS heat exchanger (CHX) submerged in the emergency cooldown tank (ECT) that can partially remove the residual heat. When the steam and non-condensable gas mixture passes through the CHX, the non-condensable gas can interrupt the condensation heat transfer in the CHX and it degrades CHX performance. In this study, condensation heat transfer experiments of steam and non-condensable gas mixture in the natural circulation loop were conducted. The pressure, temperature, and effects of the non-condensable gas were investigated according to the constant inlet steam flow rate with non-condensable gas injections in the loop.