• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.597-607
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• 2002

Electric arc furnace and converter slag are produced by about 6 millions tons in Korea at 2000 year. But compared with blast furnace slag, those are utilized only in unvalued material like landfill and road construction. There are unstable materials, like free CaO, in electric arc furnace and converter slag at steel-manufacturing process. This might cause volume expansion in concrete, if electric arc furnace and converter slag aggregates were used in concrete. This expansion may reach to crack or collapse of concrete. It is therefore settled by standard specification for concrete that electric arc furnace and converter slag aggregates have not to use in concrete. First of all, volume stability and stabilized process should be solved in electric arc furnace and converter slag aggregate to use in concrete. In this study, 6 types of aging are evaluated for effects of stabilization to reduce the expansion of electric arc furnace and converter slag. h converter slag aggregate, these types of aging are not good for volume stability for concrete aggregate, and even if converter slag aggregate is treated with aging, concrete with it has some problems that strength is reduced with curing days. But in electric arc furnace slag aggregate treated with hotwater and steam aging, the expansion of electric arc furnace slag aggregate is reduced about two times than that of converter slag aggregate, and electric arc furnace slag aggregate concrete has good results in strength compared with control concrete using crushed stone.

• Journal of the Korean Geotechnical Society
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• v.29 no.5
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• pp.29-38
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• 2013

The G-class cement is commonly used in practice for geothermal well cementing in order to protect a steel casing that is designed to transport hot water/steam from deep subsurface to ground surface during operating a geothermal power plant. In order to maintain optimal performance of geothermal wells, physical properties of the cementing material should be satisfactory. In this paper, relevant factors (i.e., groutability, uniaxial compression strength, thermal conductivity and free fluid content) of the G-class cement were experimentally examined with consideration of various water-cement (w/c) ratios. Important findings through the experiments herein are as follows. (1) Groutability of the G-class cement increases by adding a small dose of retarder. (2) There would be a structural defect caused when the w/c ratio is kept higher in order to secure groutability. (3) Thermal conductivity of the G-class cement is small enough to prevent heat loss from hot steam or water to the outer ground formation during generating electricity. (4) The G-class cement does not form free water channel in cementing a geothermal well. (5) The Phenolphthalein indicator is applicable to the distinction of the G-class cement from the drilling mud.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.534-538
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• 2002

To investigate the antimicrobial effects of Scutellariae Radix extract against Vibrio parahaemolyticus from food samples, Vibrio parahaemolyticus strains isolated from Tapes philippinarum were examined for their sensitivity to Scutellariae Radix extract. Total 66 Vibrio parahaemolyticus strains were isolated from Tapes philippinarm 72 samples (91.7%). The serotypes of isolated Vibrio parahemolytics were K-I group 7 strains (10.6%), K-IV group 5 strains (7.6%), K-II group 2 strains (3.0%), K-V group 2 strains (3.0%), K-VII group 2 strains (3.0%), K-VI group 1 strains (1.5%), K-VIII group 1 strains (1.5%) and antisera UT K-group 46 strains (69.7%) on antisera agglutination test, but K-III group and K-IX group strains were not found. The growth curves of isolates showed lag phase, logarithmic phase, stationary phase and death phase as typical sigmoid curve on the shellfish samples. After 6 hours, the group containing Scutellariae Radix extract differs from the control on shellfish samples in the growth inhibition curves, and Vibrio parahaemolyticus were inhibited in more than 1000 ppm Scutellariae Radix extract. The morphological changes were observed by transmission electron microscope and the microbial cells membrane was destroyed by Scutellariae Radix extract.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.706-713
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• 2019

In this study, basic research was conducted to provide guidelines for selecting printers and materials suitable for each application case by analyzing 3D printing method and surface characteristics of materials suitable for microfluidic system. We have studied the surface characteristics according to the materials for the two typical printing methods: The most commonly used method of Fused Deposition Modeling (FDM) printing and the relatively high resolution method of Stereolithography (SLA) printing. The FDM prints exhibited hydrophilic properties before post - treatment, regardless of the material, but showed hydrophobic properties after post - treatment with acetone vapor. It was confirmed by the observation of surface roughness using SEM that the change of the contact angle was due to the removal of the surface structure by post-treatment. SLA prints exhibited hydrophilic properties compared to FDM prints, but they were experimentally confirmed to be capable of surface modification using hydrophobic coatings. It was confirmed that it is impossible to make a transparent specimen in the FDM method. However, sufficient transparency is secured in the case of the SLA method. It is also confirmed that the electroporation chip of the digital electroporation system based on the droplet contact charging phenomenon was fabricated by the SLA method and the direct application to the microfluidic system by demonstrating the electroporation successfully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.599-606
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• 2019

Most facilities that manufacture products made from the hazardous materials operate at high temperatures and pressures. Therefore, there is a risk of fire explosion. In particular, an explosion accident is a major risk factor for facilities with hazardous materials, such as oil, chemical, and gas. Propylene is often used in sites producing basic raw materials and synthetic materials by addition polymerization at petrochemical plants. To prevent an explosion in the business using propylene, the explosion range with the oxygen concentration was calculated according to the changes in temperature and pressure using an inert gas, carbon dioxide. In these measurements, the temperature was $25^{\circ}C$, $100^{\circ}C$, and $200^{\circ}C$ and the amount of carbon dioxide in the container was $1.0kgf/cm^2.G$, $1.5kgf/cm^2.G$, $2.0kgf/cm^2.G$, and $2.5kgf/cm^2.G$. The explosion limit was related to temperature, pressure, and oxygen concentration. The minimum oxygen concentration for an explosion decreased with increasing temperature and pressure. The range of explosion narrowed with decreasing oxygen concentration. In addition, no explosion occurred at concentrations below the minimum oxygen concentration, even with steam and an ignition source of propylene.

• Journal of Space Technology and Applications
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• v.1 no.2
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• pp.217-240
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• 2021

Upon the human exploration era of the Moon, this paper introduces lunar topography and geologic fundamentals to space scientists. The origin of scientific terminology for the lunar topography was briefly summarized, and the extension of the current Korean terminology is suggested. Specifically, we suggest the most representative lunar topography that are useful to laymen as 1 ocean (Oceanus Procellarum), 10 maria (Mare Imbrium, Mare Serenitatis, Mare Tranuillitatis, Mare Nectaris, Mare Fecundatis, Mare Crisium, Mare Vaporium, Mare Cognitum, Mare Humorum, Mare Nubium), 6 great craters (Tyco, Copernicus, Kepler, Aristachus, Stebinus, Langrenus). We also suggest Korean terms for highland, maria, mountains, crater, rille, rima, graben, dome, lava tube, wrinkle ridge, trench, rupes, and regolith. In addition, we introduce the standard model for the lunar interior and typical rocks. According to the standard model on the basis of historical impact events, the lunar geological eras are classified as Pre-Nectarian, Nectarian, Imbrian, Erathostenesian, and Copernican in chronologic order. Finally, we summarize the latest discovery records on the water on the Moon, and introduce the concept of water extraction from the lunar soil, which is to be developed by the Korea Institute of Geoscience and Mineral Resources (KIGAM).

• Korean Journal of Heritage: History & Science
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• v.57 no.1
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• pp.110-123
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• 2024

Onyanghaenggung Palace(temporary palace at Onyang) is an important cultural heritage that can substantially confirm the king's visiting at hot springs based on literature records such as <Ongungyeonggoedae(溫宮靈槐臺)>, <Oncheonhaenggungdo(溫泉行宮圖)> of 『Ongungsasil(溫宮事實)』, <Younggoedaedo(靈槐臺圖)>, 『Younggoedaegi(靈槐臺記)』 and cultural properties such as Yeonggoedae(靈槐臺) and Shinjeong Monument(神井碑). Through a photo taken by Hermann Sander in 1906, it can be confirmed that the hot springs(Tangsil building) at Onyanghaenggung Palace during the Joseon Dynasty was maintained until the early Japanese colonial period. The purpose of this study is to estimate the compositions of the hot springs(Tangsil building) in Onyanghaenggung Palace based on literature records and <Oncheonhaenggungdo>(1795). To achieve these purposes, we firstly examined the changes in Onyanghaenggung Palace and the hot springs (Tangsil building); secondly, the bathing behaviors of kings were reviewed; thirdly, we organized the architectural composition of the hot springs (Tangsil building) according to "Ongung Repair" of 『Ongungsasil (溫宮事實)』; and fourthly, by comparing Sander's photo in the early days of Japanese colonial rule, the architectural composition of the hot springs (Tangsil building) in the late Joseon Dynasty was examined. The results of this study are as follows. First, the hot springs(Tangsil building) of Onyanghaenggung Palace were continuously connected to the Onjeongsil(溫井室) in the reign of King Hyeonjong and maintained until 『Hoseo-eupji』 (1871) in the late Joseon Dynasty. It matches the photograph taken by Hermann Sander(1906) and <1912 Onyang Hot Springs in Asan City>(1912) of Korea Copyright Commission during the early Japanese colonial period. Second, the various king's bathing methods during the Joseon Dynasty were adopted such as washing, spilling and bathing head while sitting on a bathing platform or chair, or exposing the steam of hot spring water, dipping feet into the water and a half-body soaking bath below the navel immersed in water. Third, the stone bathtubs of hot springs(Tangsil building) are composed of the upper bath which was hot spring water gushes out from the northwest, bends to the east, enters the middle bath, and bends to the south to come out to the outside to gather in the lower bath. Around the stone bathtubs, pebble stones brought in from Taean were laid on the floor of the hot springs(Tangsil building). From the above considerations, the compositions of the Tangsil building in Onyang Temporary Palace is based on the king's approach from the main royal building, the king's bathing method and bathing tools, the bathing behavior of enlisted medical officers and bathing assistants, and each rooms mentioned in "Ongung Repair". By comparing it with Hermann Sander's photo, the architectural compositions of the hot springs(Tangsil building) can be estimated.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.74-82
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• 1998

Combined cycle power plant is a system where a gas turbine or a steam turbine is used to produce shaft power to drive a generator for producing electrical power and the steam from the HRSG is expanded in a steam turbine for additional shaft power. The temperature of the exhaust gases from a gas turbine ranges from $400{\sim}650^{\circ}C$, and can be used effectively in a heat recovery steam generator to produce steam. Combined cycle can be classed as a topping and bottoming cycle. The first cycle, to which most of the heat is supplied, is a Brayton gas turbine cycle. The wasted heat it produces is then utilized in a second process which operates at a lower temperature level is a steam turbine cycle. The combined gas and steam turbine power plant have been widely accepted because, first, each separate system has already proven themselves in power plants as an independent cycle, therefore, the development costs are low. Secondly, using the air as a working medium, the operation is relatively non- problematic and inexpensive and can be used in gas turbines at an elevated temperature level over $1000^{\circ}C$. The steam process uses water, which is likewise inexpensive and widely available, but better suited for the medium and low temperature ranges. It therefore, is quite reasonable to use the steam process for the bottoming cycle. Recently gas turbine attained inlet temperature that make it possible to design a highly efficient combined cycle. In the present study, performance analysis of a 3 pressured combined cycle power plant is carried out to investigate the influence of topping cycle to combined cycle performance. Present calculation is compared with acceptance performance test data from SeoInchon combined cycle power plant. Present results is expected to shed some light to design and manufacture 150~200MW class heavy duty gas turbine whose conceptual design is already being undertaken.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.250-256
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• 2013

Gasoline generates organic acid and polymer (gum) by hydrocarbon oxidation depending on the storage environment such as temperature and exposure to sunlight, which can cause metal corrosion, rubber and resin degradation and vehicle malfunction caused by accumulation in fuel supply system. The gasoline which has not been used for a long time in bi-fuel (LPG-Gasoline) vehicle causes problems, and low octane number gasoline have evaporated into the field, but the exact cause has not been studied yet. In this study, we suggest a plan of quality management by investigating the gasoline oxidation behavior. In order to investigate the oxidation behavior of gasoline, changes of gasoline properties were analyzed at various storage conditions such as storage time, storage vessel type (vehicle fuel tank, PE vessel and Fe vessel) and storage circumstances (sunlight exposure and open system, etc.). Currently distributing gasoline and bioethanol blended fuel (blended 10%) were stored for 18 weeks in summer season. The sample stored in PE vessel was out of quality standard (octane number, vapor pressure, etc.) due to the evaporation of the high octane number and low boiling point components through the vessel cap and surface. Especially, the sunlight exposure sample stored in PE vessel showed rapid decrease of vapor pressure and increase of gum. Bioethanol blended fuel showed similar results as gasoline.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.11
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• pp.445-452
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• 2017

Electric pole is a supporting beam used for power transmission/distribution which accelerometer are used for measuring a external force. The meteorological condition has various effects on the external forces of electric pole. One of them is the elasticity change of the aerial wire. It is very important to perform modelling. The acceleration sensor is converted into a pitch and a roll angle. The meteorological condition has a high correlation between variables, and selecting significant explanatory variables for modeling may result in the problem of over-fitting. We constructed high deviance explained model considering multicollinearity using the Generalized Additive Model which is one of the machine learning methods. As a result of the Variation Inflation Factor Test, we selected and fitted the significant variable as temperature, precipitation, wind speed, wind direction, air pressure, dewpoint, hours of daylight and cloud cover. It was noted that the Hours of daylight, cloud cover and air pressure has high explained value in explonatory variable. The average coefficient of determination (R-Squared) of the Generalized Additive Model was 0.69. The constructed model can help to predict the influence on the external forces of electric pole, and contribute to the purpose of securing safety on utility pole.