• Journal of the Korean Ceramic Society
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• v.22 no.3
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• pp.35-40
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• 1985

The composition of the base glass was determined to be $Na_2O$ 15, $Fe_2O_3$ 35, $B_2O_3$ 0~20, $P_2O_5$ 30~50 by mole percent. The heating temperature for nucleation was determined by means of thermal expansion curve. Crystalline phases were investigated by X-ray diffraction method and I.R Spectra. Electrical conductivities of glass spec-imens were observed in the temperature range 25~20$0^{\circ}C$ The activation energies of these specimens were caculated. The results obtained were as follows : 1) The limit composition of the melts 15mol% $Na_2O$ 35mole% $Fe_2O_5$ 20mole% $B_2O_3$ 30mole% $P_2O_5$ was able to be formed into desired shapes during cooling, . 2) In the measurement of d. c conductivity($\delta$) on the glasses in the system $15Na_2O-35Fe_2O_3$-$B_2O_3$-(50-x) $P_2O_5$ the values decreased by replacing 5 mole% $P_2O_5$ with $B_2O_3$ 3) The d. c conducties of heat treated samples were increased by replacing $P_2O_5$ with $B_2O_3$ 4) $B_2O_3$ contributed to precipitate crystals such as${\gamma}$-$Fe_2O_3$ $Fe_3O_4$ which had the advantage of electronic conduction in heat treated samples. 5) The slope plotted Log($\delta$) versus 1/T in this glass system was linear in the measured temperature range.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.05a
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• pp.39-44
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• 1998

현재 국내에 보급되어 있는 현대화 온실 203개를 대상으로 냉난방과 관련된 설비현황을 조사하여 분석한 결과를 요약하면 다음과 같다. \circled1 온실의 건설방위는 남북동(58.1%)과 동서동(26.8%)이 대부분이었고, 철골온실은 Wide-span형이 81.8%, 플라스틱온실은 1-2W형 온실이 97.5%였다. 휴작하는 온실은 약 41%정도였고, 재배작물은 채소류가 약 80%, 화훼류가 약 20%정도였으며, 재배방식은 철골온실의 경우 양액재배가 57.2%, 플라스틱온실에서는 토양재배가 88.5%였다. \circled2 온실의 외부 피복재는 철골온실은 유리가 92.2%, 플라스틱온실에서는 PE가 43.3%, EVA가 51.9%로 대부분이었다. 철골온실은 1중피복이 98.7%로 거의 전부이었고, 플라스틱온실에서는 2중피복이 78.7%로 나타나, 철골온실에서 보온커튼을 통한 보온성 향상과 밀폐성이 더욱 중요함을 알 수 있다. \circled3 보온용 피복재는 부직포가 64.9%로 가장 많았고 대부분 2층커튼(85.9%)이었으며, 개폐방식은 대부분 예인식(92.7%)의 자동개폐방식(75.2%)이었다. 한편 바닥을 피복한 온실은 약 30% 정도로 나타나, 바닥피복으로 인한 축열이나 반사효과를 감안할 때 효율적인 바닥처리가 요망된다. \circled4 온실의 난방방식은 철골온실에서는 온수안방(47.3%)이 온풍난방(33.8%)보다 다소 많았으며, 플라스틱온실에서는 대부분 온풍난방(90.8%)이었다. 온실의 난방위치는 대부분 지상난방(89.8%)이었고 지중난방은 극소수로 나타나, 앞으로 지중난방을 통한 난방비 절감과 품질향상에 관한 실용화 연구가 요망된다. 난방용 연료는 대부분 경유(83.9%)로 나타나, 난방비를 절감할 수 있는 저가의 연료를 사용할 수 있는 난방시스템의 개발이 요청된다. \circled5 온실의 냉방방법은 차광(51.8%)과 지붕살수(33.9%)가 대부분이었으며 미스트와 포그시스템을 설치한 온실은 소수에 불과하였고, 극소수의 온실에서는 지붕위나 온실내에 지붕면과 평행하게 설치한 경우도 있었다.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.83-88
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• 2016

In this study, previously reported surplus solar energy-related study result and current status of fan coil unit (FCU) for cooling and heating installed in the current sites were briefly examined and then a method to determine the number of FCUs required to recover surplus solar energy was schematically proposed to provide basic data for researchers and technical engineers in this field. The maximum, mean, and minimum outside temperatures during the experiment period were about $28.2^{\circ}C$, $4.4^{\circ}C$, and $-11.5^{\circ}C$, respectively. The horizontal surface solar radiation level outside the greenhouse was in a range of $0.8-20.5MJ{\cdot}m^{-2}$ and mean and total solar radiation were $10.8MJ{\cdot}m^{-2}$ and $1,187.5MJ{\cdot}m^{-2}$. The mean temperature and relative humidity in the greenhouse during the daytime were in a range of 18.8-45.5 and 53.5-77.5%. The total surplus solar energy recovered from the greenhouse during the experiment period was approximately 6,613.4MJ, which could supplement about 6.7% of the total heating energy 98,600.2 MJ. In addition, the number of FCUs installed for heating varies case to case, although similar FCUs are used. Thus, it is necessary to study the installation height, orientation and installation distance as well as the appropriate number of FCUs from the efficient and economical viewpoints. The required numbers of FCUs for surplus solar energy recovery were 8.4-10.9units and 6.1-8.0units based on air mass and circular flow rate that passed through the FCUs. Considering calculation methods and the risks such as efficiency and use environments of FCUs, it was found that about nine units (one unit per $24m^3$ approximately) needed to be installed. The required number of FCUs for surplus solar energy recovery was around one unit per $24m^3$ approximately.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.32-43
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• 2014

This study set out to identify the importance of each factor influencing facility selection with a survey among public medical facilities under the category of public buildings and apply the importance of economy, technology and environment with the weighting factor method, thus proposing optimal application plans. The research content of each section can be summarized as follows:1) Estimated energy consumption according to the energy simulation was 65,129MWh/yr, which was 18.7% higher than that according to the calculation equation. Of the energy consumption, more than 80% was used by heating and cooling facilities and construction facilities, and 20% was used by electronics such as medical equipments and in and outdoor lighting. 2) The results of a survey on the factors influencing the importance when selecting a new and renewable energy system reveal that the upper items had a priority in economy, environment, and technology in the descending order and that the lower item shad a priority in initial investments, maintenance and repair costs=energy costs, supply reliability, energy efficiency and $CO_2$ emissions in the descending order. 3) The application alternatives were analyzed in economy, technology, and environment. As a result, a geothermal system turned out to be the most excellent one a cross all the upper and lower comparison items. Of the other systems, a solar thermal system was superior in initial investments, maintenance and repair costs, and energy efficiency, where as a photovoltaic system was superior in energy costs, supply reliability, and $CO_2$ emissions. 4) As for the mixed application ratio among economy, technology, and environment, when the percentage of a geothermal system was approximately 80% or higher in anew and renewable energy system, it was the best and most optimal application plan.

• Korean Journal of Human Ecology
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• v.18 no.5
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• pp.1135-1145
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• 2009

This study was conducted to investigate the situation of internal facilities and sanitary management of elementary, middle, and high school foodservice in Chonbuk area. Self administered questionnaires were collected from 252 nutrition teachers and school dietitians. Statistical data analysis was completed using a SPSS 11.5 program. The results are summarized as follows: Approximately 99.2% of the subjects were women and those who were married accounted for 76.6%. Those in their 30s to 40s accounted for over 87%, those with more than 11 years experience accounted for 56.8%, and those 69.0% were regular nutrition teachers. Among the 280 school foodservice systems, 51.6% of the schools were located in urban areas and 48.0% in rural areas. About 68% of the schools prepared meals the conventional way and 32.3% prepared them the commissary way. The number of employees accounted for in the schools was 37.7% with 1 to 3 employees, 27.8% with 4 to 6 employees, and 25.4% with 7 to 9 employees. About 54% of schools have an expectance of school meal service for more than 11 years. However 67.5% of their facilities had not been remodeled since the implementation of the foodservice. As a result of the conditions of the school foodservice facilities, there were significant differences between elementary and middle & high schools; preparation room (p<0.01), toilet (p<0.01), and boiler room (p<0.01). About 62% of the nutrition teachers responded that they were dissatisfied with the situation of the facilities (e.g. size and materials of the kitchen, heating and cooling systems). The washing and disinfection methods in elementary, middle and high schools were very different, because they had no sanitizers and disinfectant guidelines. Therefore the governmental regulating agencies must review and approve of the plans prior to new construction or extensive remodeling of the school foodservice facilities. In addition, we suggest that it is necessary to provide practical sanitizers and disinfectant guidelines and other useful education.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.16-20
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• 2009

To develop health functional foods using high amylose rice flours, the properties of flours prepared from domestic high amylose rice varieties, Goamy2 and Goamy, and imported rice from Thailand were investigated. After soaking the rice grains and drying, the dry-milled rice flours were passed through a 120-mesh sieve. The protein and total starch contents of the Goamy2 rice flour were lowest, but its crude lipid and ash contents were highest among the flours. In addition, apparent amylose content, water binding capacity, and total dietary fiber were highest in the Goamy2 flour (36.2, 255.0, and 9.2%, respectively). The Thai rice flour had the highest swelling power, whereas the Goamy2 flour had the lowest swelling power and solubility. By Rapid visco-analysis, the Thai flour showed the highest peak and total setback viscosities and lowest breakdown viscosity. The pasting pattern of the Goamy2 flour was different from that of the other flour, where low viscosity was maintained during heating and cooling. Goamy and Thai rice flours showed an A type crystallinity, but Goamy2 flour showed a B type crystallinity similar to high amylose maize starch. The Goamy2 flour presented a dull and yellowish color, and the lowest lightness (L) value and the highest yellowness (+b) value.

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.401-418
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• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.39-51
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• 2007

Unconsolidated and permeable alluvial deposit composed of sand and gravel is distributed along the fluvial plain at the Iryong study area. Previous studies on the area show that a single alluvial well can produce at least 1,650m3d-1 of bank infilterated shallow groundwater(BIGW) from the deposit. This study is aimed to evaluate and simulate the influence that seasonal variation of water levels and temperatures of the river have an effect on those of BIGW under the pumping condition and also to compare seasonal variation of COPs when indirectly pumped BIGW or directly pumped surface water are used for a water to water heat pump system as an heat source and sink using 3 D flow and heat transport model of Feflow. The result shows that the magnitude influenced to water level of BIGW by fluctuation of river water level in summer and winter is about 48% and 75% of Nakdong river water level separately. Seasonal change of river water temperature is about $23.7^{\circ}C$, on other hand that of BIGW is only $3.8^{\circ}C$. The seasonal temperatures of BIGW are ranged from minimum $14.5^{\circ}C$ in cold winter(January) and maximum $18.3^{\circ}C$ in hot summer(July). It stands for that BIGW is a good source of heat energy for heating and cooling system owing to maintaining quite similar temperature($16^{\circ}C$) of background shallow groundwater. Average COPh in winter time and COPc in summer time of BIGW and surface water are estimated about 3.95, 3.5, and about 6.16 and 4.81 respectively. It clearly indicates that coefficient of performance of heat pump system using BIGW are higher than 12.9% in winter time and 28.1% in summer time in comparision with those of surface water.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.942-948
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• 2010

In this study we aims to examine the effects of 0.5 mol% $Cr_2O_3$ addition on the reaction, microstructure development, resultant electrical properties, and especially the bulk trap and interface state levels of ZnO-$Bi_2O_3-Sb_2O_3$ (Sb/Bi=0.5, 1.0, and 2.0) systems (ZBS). The samples were prepared by conventional ceramic process, and characterized by XRD, density, SEM, I-V, impedance and modulus spectroscopy (IS & MS) measurement. The sintering and electrical properties of Cr-doped ZBS (ZBSCr) systems were controlled by Sb/Bi ratio. Pyrochlore ($Zn_2Bi_3Sb_3O_{14}$) was decomposed more than $100^{\circ}C$ lowered on heating in ZBS (Sb/Bi=1.0) by Cr doping. The densification of ZBSCr (Sb/Bi=0.5) system was retarded to $800^{\circ}C$ by unknown Bi-rich phase produced at $700^{\circ}C$. Pyrochlore on cooling was reproduced in all systems. And $Zn_7Sb_2O_{12}$ spinel ($\alpha$-polymorph) and $\delta-Bi_2O_3$ phase were formed by Cr doping. In ZBSCr, the varistor characteristics were not improved drastically (non-linear coefficient $\alpha$ = 7~12) and independent on microstructure according to Sb/Bi ratio. Doping of $Cr_2O_3$ to ZBS seemed to form $Zn_i^{..}$(0.16 eV) and $V^{\bullet}_o$ (0.33 eV) as dominant defects. From IS & MS, especially the grain boundaries of Sb/Bi=0.5 systems were divided into two types, i.e. sensitive to oxygen and thus electrically active one (1.1 eV) and electrically inactive intergranular one (0.95 eV) with temperature.

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.3
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• pp.23-30
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• 2022

In this study, in order to grasp the current situation of indoor environmental pollution and indoor ventilation in one-room around the university in the post-corona era, we analyzed the experimental data and conducted a questionnaire survey on university students. By analyzing the content, the effects of formaldehyde, dust and other pollution on the human body, which are usually not easily detectable, are digitized and more easily taken into account. Among the experimental results, the concentration of VOC and HCHO, gas pollutants among indoor pollutants, exceeded the recommended criteria of the Ministry of Environment in most studio apartments. Overall, the average CO₂ concentration was lower than the Ministry of Environment's maintenance standard (1000ppm), but it was relatively high in summer and winter, and it is believed to be caused by cooling and heating in an enclosed space. The levels of PM2.5 and PM10, particulate pollutants, increased in November and December, and it is believed that ventilation defects due to degradation in external temperature. There was no clear difference between the two types, and there was a very high correlation between PM2.5 and PM10, HCHO and VOC. It was found that temperature was closely correlated with all sources except CO₂, and humidity was closely correlated with all sources except PM2.5 and PM10. Health risk assessment was conducted for formaldehyde. The average ECR of studio R2 in May was 3.91E^-4, and the ECR figure in September was 3.65E^-4, which was very high compared to other residential spaces. The R2 level was calculated as 4 people per 10,000 people in the lifetime risk of cancer of residents, exceeding the allowable risk. R8 also showed higher ECR results than other spaces after R2, especially in October, 2.01E^-4, six times higher than R7 measured in October, and 1.87E^-4 in July, four times higher than R9.