• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.2
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• pp.20-41
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• 2023

Recently, urban shrinkage due to low birth rate and aging population and the decline of local cities are causing a new urban problem of empty houses. This study examines the distribution of vacant homes using spatial panel data collected from 2015 to 2019 at local administraitve districts and estimates the factors of vacant house occurrence using a spatial panel model considering spatio-temporal dependency. As a result, the spatio-temporal dependence of vacant houses was identified and it was estimated using spatial panel model not OLS model. Based on the spatial panel model, it was found that the most influential factor in the occurrence of vacant houses was the housing-related factor. This result shows that policy considerations for housing supply are necessary for the management of vacant housing as well as population movement and poor infrastructure.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.105-112
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• 2019

Fine aggregate made of ferronickel slag(FNS) is similar to natural fine aggregates and is used in concrete structures both domestically and abroad, but its applications and research areas are limited. In this research, in order to expand the availability of FNS and improve the performance of cement mortar products, the applicability of FNS on dry mortar for floor was examined. Experimental results show that FNS improves flow of cement mortar because it has low absorption rate, spherical shape, and glassy surface. Also, the high stiffness of the FNS aggregate itself is considered to contribute to the improvement of cement mortar quality such as crack reduction by improving the compressive strength and shrinkage reducing. In addition, when FNS fine aggregate is applied, it was possible to secure the impact sound insulation performance equal to or higher than that of mortar using natural fine aggregate.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.70-78
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• 1997

3Y-TZP/SUS316 Functionally Graded Material (FGM) was fabricated by slip casting method. Alumina mold was used to overcome problems of gypsum mold in slip casting process, and the optimal dispersion con-ditions of 3Y-TZP/SUS316 binary slurries was determined using electrokinetic sonic amplitude and a viscometer, and observing sedimentation behavior. The properties of the specimens casted by gypsum mold and alumina mold were compared in terms of changes in shrinkage rate, drying and sintering conditions, and microstructure. It was found that the specimens obtaine from the alumina mold showed a clean surface, easier thickness control of each layer, and higher productivity. Especially, no degradation was observed in the SUS316 prepared using alumina mold. Thus it is desirable to use porous alumina mold rather than gyp-sum mold for the slip casting of 3Y-TZP/SUS316-FGM.

• Journal of Forest and Environmental Science
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• v.39 no.1
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• pp.27-39
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• 2023

Twenty-five Eucalyptus clones (14 E. camaldulensis - EC and 11 interspecific eucalypt hybrid clones - EH) grown in three contrasting sites were evaluated for the growth and few wood traits at 4 years of age. The stability, genotype-site interaction and suitability of these clones for pulp and solid wood industry sectors were studied. Growth of eucalypt clones was significantly higher at site 1 with higher rainfall, but wood density did not differ significantly from lower rainfall sites. Kraft pulp yield (KPY) decreased from sites 1 to 3 based on moisture availability, but not between two groups of clones. Volumetric shrinkage (VS) was significantly higher in EC clones at site 3 with lowest rainfall, but there was no specific trend at other two sites with maximum (site 1) and intermediate (site 2) rainfall. The mechanical traits modulus of rupture (MOR) and modulus of elasticity (MOE) were at par in sites 1 and 2, but significantly lower at the driest site 3. The growth rate had a significant positive correlation with KPY, MOR and MOE and a negative correlation with VS, but no significant impact on wood density in both groups of clones. Genotype×environment interaction (G×E) was evident in most traits due to the difference in response of clones to moisture availability. Since wood density was negatively correlated to KPY, it has to be kept at an optimum level for the profitability of pulp industry. There was no significant difference between EC and EH clones for most traits except VS at site 3. Stability of clones varied across sites in different traits, and hence clones may be selected for deployment at each site by screening for growth, followed by wood density, considering the relationship of growth and density with other traits required by pulp and solid wood industry sectors.

• Membrane Journal
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• v.26 no.4
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• pp.310-317
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• 2016

Lithium ion secondary battery (LISB) is an energy conversion system operated via charging-discharging cycle based on Lithium ion migration. LISB has a lot of advantages such as high energy density, low self-discharge rate, and a relatively high lifetime. Recently, increasing demands of electric vehicles have been encouraging the development of LISB with high capacity. Unfortunately, it causes some critical safety issues. It includes dendrite formation on negative electrode, resulting in electric shortage problems and battery explosion. Also, the elevated temperatures occurred during the LISB operation induces thermal shrinkage of polyolefin (e.g., polyethylene and polypropylene) separators. Consequently, the low thermal stability leads to decay of LISB performances and the reduction of lifetime. In this study, sulfonated poly (arylene ether sulfone) (SPAES) random copolymers were used as key materials to prepare polyolefin pore-filling separator. The resulting separators were evaluated in the term of metal ion chelation capability associated with dendrite formation, $Li^+$ ion conductivity and thermal durability.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.17-22
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• 2004

In this study, BNT($BaO-Nd_{2}O_3-TiO_2$) and $70P_{2}O_5-5B_{2}O_3-(25-x)BaO-xNa_{2}O$ glass-ceramic composites were fabricated and investigated in order to apply for low temperature cofired ceramic. The prepared BNT based glass-ceramic composites were sintered at $800{\sim}950^{\circ}C$ with the glass fit contents ranging from 10 to $15\;wt\%$. The properties such as sintering and dielectric property were investigated in the ceramic compositions according to the phosphate glass frit. The dielectric constant was varied between 10 to 40 and shrinkage rate was increased according to increasing glass frit.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.764-768
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• 1993

This study was developed a computer-controlled automatic drying system. In order to control automatically the temperature, relative humidity weight of the sample, drying system with computer and connecting parts such as microcomputer, PC-Lab card, Op. Amp., and relay system were developed for controlling the heater, fan, humidifier and dehumidifier. Using this system, drying characteristic mechanism of ginseng were investigated. The increase of drying temperature decreased Hunter L value and increased a and b value. The hardness and shrinkage rate of white ginseng had a increasing tendency with the increase of drying temperature. Crude saponin content was not affected by drying temperature and relative humidity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.144-151
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• 2008

In this paper, we propose a video streaming server that guarantees a certain level of quality when a server should serve video streaming service to multiple heterogenous clients simultaneously with TCP transport. If each heterogeneous client requests video streaming service in according to its own requirement such as bitrate of content and these requests are accepted by a server, then TCP flows for each video streaming session fairly share limited uplink bandwidth of the server. At this time, because TCP's bandwidth fair-share characteristics can result in bandwidth shrinkage of higher bitrate video streaming session, the client of higher bitrate video may suffer sluggish playback which is related with streaming QoS degradation. To tackle this problem, our proposed server system uses multiple TCP connections adaptively for each video streaming session depending on the anticipated status of the client playout buffer. Simulation results show that our proposed algorithm can successfully reduce the occurrence of playout buffer underrun and enhance streaming quality for whole video clients.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.840-846
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• 2003

Physiochemical and sensory properties of muskmelon pickles were investigated under salting condition using deep seawater salt, sun-dried salt and purified salt. The changes of weight, shrinkage rate salinity and pH of muskmelon during salting time were almost nothing shown. Turbidity of pickle juice was the highest in salt solution using sun-dried salt and was almost nothing shown in deep seawater salt and purified salt. Solid content of pickle juice was higher in pickle juice using sun-dried salt than deep seawater salt and purified salt. The calcium content of muskmelon salted by deep seawater salt and sun-dried salt were increased to 4.3 times and 3.7 times, respectively. Hardness became a little higher on muskmelon using deed seawater salt ann sun dried salt than purified salt. In organoleptic result, color, flavor, taste, texture and overall palatability of muskmelon salted by deep seawater salt became higher in other salt solution (sun-friend salt and purified salt).

• Transactions of Materials Processing
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• v.26 no.5
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• pp.306-313
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• 2017

This study investigated the microstructure, tensile strength, and high cycle fatigue properties of ADC12 aluminum alloys with different $Mg+Al_2Ca$ contents manufactured using die casting process. Microstructural observation identified the presence of ${\alpha}-Al$, eutectic Si, $Al_2Cu$, and Fe-intermetallic phases. The increase of $Mg+Al_2Ca$ content resulted in finer pore size and decreased pore distribution. Room temperature tensile strength tests were conducted at strain rate of $1{\times}10^{-3}/sec$. For 0.6%Mg ADC12, measured UTS, YS, and El were 305.2MPa, 157.0MPa, and 2.7%, respectively. For 0.8%Mg ADC12, measured UTS, YS, and El were 311.2 MPa, 159.4 MPa, and 2.4%, respectively. Therefore, 0.8% ADC12 alloy had higher strength and slightly decreased elongation compared to 0.6% Mg ADC12. High cycle fatigue tests revealed that 0.6% Mg ADC12 alloy had a fatigue limit of 150 MPa while 0.8% Mg ADC12 had a fatigue limit of 160MPa. It was confirmed that $Mg+Al_2Ca$ added ADC12 alloy achieved finer, spherical eutectic Si particles, and $Al_2Cu$ phases with greater mechanical and fatigue properties since size and distribution of pores and shrinkage cavities decreased as $Mg+Al_2Ca$ content increased.