• Economic and Environmental Geology
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• v.42 no.6
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• pp.541-548
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• 2009

The Dongrae thermal water area located at the southeastern marginal part of the Korean Peninsula is one of the oldest hot springs in Korea. The Dongrae thermal water shows Na-Cl type of water chemistry, whereas the shallow cold groundwater is Ca(-Na)-$HCO_3$ type. In this paper, we discuss the age of the Dongrae hot spring, i.e. groundwater cycle among meteoric water-surface water-shallow groundwater-hot spring water. The $^{87}Sr/^{86}Sr$ ratios of the thermal water in Dongrae area range from 0.705663 to 0.705688 and are lower than those of groundwater, surface water and rain water as well as aquifer bearing granite. These Sr isotopic signatures in the Dongrae thermal water indicate that the circulation rate between thermal water and current meteoric water including groundwater, surface water and rain water in the Dongrae area should be very slow. The $^{14}C$ age of the Dongrae hot spring water range from $1,271{\pm}36$ BP(before present) to $2,467{\pm}36$ BP whereas that of the shallow groundwater is $-495{\pm}33$ BP. This suggests that the period of groundwater cycle among meteoric water, surface water, shallow groundwater and hot spring should be more than 1,270 years. Then, it also indicates that the present Dongrae hot spring may be a mixed water between the old thermal water heated for at least 1,270 years and the present shallow cold groundwater.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.3
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• pp.231-238
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• 2003

An experimental study was performed to improve a domestic hot water boiler with a coil type heat exchanger. By using Korean Standard B 8107, B 8021 and B 6205, the boiler efficiency for heating, bathing and combution are calculated. Finally, the efficiency of the boiler are compared with those of the commercial production. On the whole, the performance of the hot water generator is higher than that of the other generator.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1418-1423
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• 2009

This study describes experimental study on the performance characteristics with load condition in hybrid solar heating system during spring season. The room temperatures, the hot water conditions and the lower part temperatures of heat storage tank were changed to analyze the system performances. As a results, the hot water was significantly affected by the ambient temperature. The indoor setting temperature affected the solar fraction. When the low part temperature of the storage tank increased, the temperature of the hot water rose and the temperature of the hot water in morning was affected by the ambient temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.2
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• pp.127-133
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• 2002

The objectives of this paper are to develop an advanced GAX cycle named HGAX (Hybrid Generator Absorber heat exchanger) cycle, and to study the effect of key parameters on the cycle performance and the hot-water temperature from the condenser. New types of the HGAX cycle are developed by adding a compressor between the generator and the condenser- Type C (performance improvement and reduction of the generator temperature) and Type D (Hot-water temperature application). The solution temperature in the generator outlet is reduced to 168$^{\circ}C$ with the COP improvement of 19% compared to the standard GAX cycle. The hot-water temperature from the condenser is raised to 106$^{\circ}C$ for panel heating (Ondol heating) application.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.13-19
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• 2018

The Effects of hot water supply temperature on indoor thermal characteristics for floor radiant heating system in residential apartment were researched by computer simulation. The parametric study on hot water supply temperatures with different outdoor air temperatures was done with regard to energy performance and control characteristics, respectively. As a result, the maximum overshoot of indoor air temperature and energy consumption were reduced by adjusting the hot water supply temperatures with outdoor air temperatures.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.8
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• pp.629-635
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• 2008

Recently, microturbines have received attention as a small-scale distributed power generator. Since the exhaust gas carries all of the heat release, the microturbine CHP (combined heat and power) system is relatively compact and easy to maintain. Generating hot water or steam is usual method of heat recovery from the microturbine. In this work, a heat recovery unit producing hot water was installed at the exhaust side of a 30 kW class microturbine and its performance characteristics following microturbine power variation was investigated. Heat recovery performance has been compared for different operating conditions such as constant hot water temperature and constant water flow rate. In particular, the influence of water flow rate and hot water temperature on the recovered heat was analyzed.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.818-824
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• 2019

In this study, the direct water quenching technique is applied to validate the applicability of direct water quenching as a cooling method in the hot stamping process of 3.2 mm thick boron steel sheet. Cooling performance of conventional die quenching and direct water quenching is compared. Higher cooling rate is obtained by hot stamping with direct water quenching compared to die quenching. As the flow rate of cooling water increases, the cooling rate increases, and a high cooling rate of 71 ℃/s is achieved under flow rate conditions of 0.8 L/min. Through direct water quenching, the cooling time required for sufficient cooling of the sheet is reduced. Full martensitic microstructure is obtained under flow rate condition of 0.8 L/min. Hardness increases with increasing flow rate. From these results, it is verified that the direct water quenching is applicable to the hot stamping of thick boron steel sheet.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.53-65
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• 2020

This study aimed to provide a basic information for managing the water quality of national and regional 1st rivers in Gyeongnam by analyzing the emerging hot spot patterns in BOD, T-P, and TOC, and by grouping the changing trends into clusters. The emerging hot spot analysis for each water quality item was implemented in ArcGIS Desktop with monthly water quality data from 96 water environmental monitoring stations in Gyeongnam, and then four patterns of water quality change were classified by the K-mean cluster analysis. As for BOD, persistent cold spot pattern covered about 42.9% of target rivers, and T-P concentration tended to be low or be getting lower at over 70% of target rivers. While, for TOC, about 70% of target rivers resulted in oscillating hot spots. In addition, the cluster analysis showed that the downstream of Nakdong river had the top priority in terms of water quality management because of the increasing concentration for all the three water quality.

• Journal of Mushroom
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• v.13 no.1
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• pp.1-10
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• 2015

Russula rosacea, a mycorrhizal fungus, has been used for edible and medicinal purposes. This study was conducted to evaluate the in vitro antioxidant, anti-hyperglycemic, anti-cholinesterase, and nitric oxide inhibitory effects of the fruiting bodies from R. rosacea extracted with methanol, and hot water. The 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activities of the methanol and hot water extracts (2.0 mg/ml) of R. rosacea were comparable with BHT, the positive control. The chelating effects of the mushroom and hot water extracts were significantly higher than that of BHT. The reducing power of methanol and hot water extract (6 mg/ml) were significantly lower than that of BHT. Seven phenolic compounds were detected from acetonitrile and hydrochloric acid solvent extract of the mushroom. alpha-amylase and alpha-glucosidase inhibitory activities of methanol and hot water extracts were lower than that of acarbose, the positive control. The acetylcholinesterase and butyrylcholinesterase inhibitory effects were moderate compared with galanthamine, the standard drug. Nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 cells were inhibited significantly by the mushroom extracts in a concentration dependent manner. Therefore, we demonstrated that fruiting bodies of R. rosacea possess in vitro antioxidant, anti-hyperglycemic, anti-cholinesterase, and NO production inhibitory activities. The experimental results suggest that the fruiting bodies of R. rosacea are good natural antioxidant, anti-hyperglycemic, anti-cholinesterase, and anti-inflammatory sources.

• The Journal of Internal Korean Medicine
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• v.27 no.1
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• pp.55-71
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• 2006

Objectives : To find out more pharmacologically efficient way of extraction of herbal dicoction, Gamichungsangbohatang (GMCSBHT). Methods : Several main components of GMCSBHT was compared and analysed between hot water extract of GMCSBHT and Alcohol(70% ethanol) extract of GMCSBHT via HPLC method. Results : Hot water extract of GMCSBHT showed relatively more component content than ethanol extract of GMCSBHT. Also weighted mean of main components of hot water extraction of GMCSBHT was higher than that of alcohol extract of GMCSBHT. But from chromatographic pattern analysis of matching ratio and similarity ratio showed that these two forms of extracts might have different chemical composition, and 3D PDA plot of alcohol extract of GMCSBHT showed high peaks near UV $190{\sim}220nm$ which was invisible in hot water extract of GMCSBHT. Conclusion : Alcohol extract of GMCSBHT may have some special components which do not exist in hot water extract of GMCSBHT.