• 보존과학연구
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• s.27
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• pp.165-180
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• 2006

The research was conducted to understand type of iron used by those who lived at dwelling site of Yangsoo-ri in between the first century B.C. and the first century A.D. to make steel products and their technique such as steel making process and heat treatment, based on micro structure information obtained through microscopic metallographic structure analysis with SEM-EDS of six steel productsexhumed at the site. Key findings are summarized as below. In the sense that Si-Ca-Al style and less than 0.5% of Ti were found in the non-metallic inclusion, the material used for forged iron ware was magnetite resolved in that. It is, however, unclear whether magnetite was resolved at high temperature or at low temperature. Microscopic structure analysis revealed that forged steel products were made through repeated hot working, the technique of molding by hitting after heating in the process of resolving and molding iron. As a result, the iron used here for the products was not the iron ore which was produced through resolution from discarded cast iron axe, ingot iron. It is probable that to make those steel products, disposed-of cast iron was reused after being molded by decarburizing. Although a few of relics were analyzed for the research, they were of critical importance in defining the process of ironware production from the first century B.C. and the first century A.D. at the Yangsoo-ri region. Judging from the iron from A-19 dwellingsite, it is possible to conclude that the iron was manufactured from cast iron decarburized and yet more research has to be done into relics yetto be exhumed in order to ascertain the finding. All of these findings are believed to play a critical role in further studies to define the steel-manufacturing technique used on the central Korean peninsular in the ancient times.

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.146-151
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• 2011

The formation of Li-Si-O phases, $Li_4SiO_4$ and $Li_2SiO_3$ from the starting materials SiO and $Li_2O$ are analyzed using Vienna Ab-initio Simulation (VASP) package and the total energies of Li-Si-O compounds are evaluated using Projector Augmented Wave (PAW) method and correlated the structural characteristics of the binary system SiO-$Li_2O$ with experimental data from electrochemical method. Despite $Li_2SiO_3$ becomes stable phase by virtue of lowest formation energy calculated through VASP, the experimental method shows presence of $Li_4SiO_4$ as the only product formed when SiO and $Li_2O$ reacts during slow heating to reach $550^{\circ}C$ and found no evidence for the formation of $Li_2SiO_3$. Also, higher density of $Li_4SiO_4$(2.42 g $ml^{-1}$) compared to the compositional mixture $1SiO_2-2Li_2O$ (2.226 g $ml^{-1}$) and better cycle capacity observed through experiment proves that $Li_4SiO_4$ as the most stable anode supported by better cycleabilityfor lithium ion battery remains as paradox from the point of view of VASP calculations.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.63.2-63.2
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• 2014

As a part of the "Dust, Ice, and Gas In Time" (DIGIT) key program on Herschel, we observed GSS30-IRS1, a Class I protostar located in Ophiuchus (d =125 pc), with Herschel/Photodetector Array Camera and Spectrometer (PACS). More than 70 lines were detected within a wavelength range from 50 ${\mu}m$ to 200 ${\mu}m$: CO lines from J = 14-13 to 41-40, several $H_2O$ lines of Eup = 100 K to 1500 K, 16 transitions of OH rotational lines, and two atomic [O I] lines at 63 and 145 ${\mu}m$. The [C II] line, known as a tracer of externally heated gas by the interstellar radiation field, is also detected at 158 ${\mu}m$. All lines, except [O I] and [C II], are detected only at the central spaxel of $9^{\prime\prime}.4{\times}9^{\prime\prime}.4$. The [O I] emission is extended along a NE-SW orientation, which is consistent with the known outflow direction, while the [C II] line is detected over all spaxels. One possible explanation of the detection of the [C II] line and no correlation of its spatial distribution with any other molecular emission is the existence of the enhanced ISRF nearby GSS30-IRS1. One interesting feature of GSS30-IRS1 is that the continuum emission is extended beyond the point-spread function (PSF), unlike the molecular line emission, indicative of significant external heating. The best-fit continuum model of GSS30-IRS1 with the physical structure including flared disk, envelope, and outflow shows that the internal luminosity is 11 $L_{\odot}$, and the region is also externally heated by a radiation field enhanced by a factor of 25 compared to the local standard interstellar field.

• Journal of the Korean housing association
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• v.20 no.6
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• pp.19-29
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• 2009

The purpose of this study is to clarify the spatial changes that have taken place in the main rooms (Anbang) and kitchens of traditional Utbangkkeokeum houses in Cheongju city, located on the central inland of Korea. These houses consist of a main house (Momchae) and a single-wing house (Nalgaechae), creating an ㄱ-shaped plan. The kitchen is in the front of the Nalgaechae, and the Anbang is at the rear. For the Momchae, the main hall (Daechung) is next to the Anbang, which is at the end of the Nalgaechae, and the room (Gunnunbang) is situated across from the Daechung. This study is based on the assumption that these houses have been conserved and altered from their original forms. As a result of alterations, many changes have occurred to the main room and kitchen spaces. The traditional main room is connected with two rooms (Utbang and Araebang), new standup kitchens are introduced, and floor heating systems are installed. The Anbang has maintained its sedentary lifestyle and the space for major daily activities such as sleeping and TV viewing. Also, TV viewing is a distinctive feature for residential purposes and the bedding is located in such a position that it is easy to observe any exterior movement for the elderly living alone. The layout of the standup kitchen has been altered to maintain the previous circulation, position and function of the entrance. Also, the kitchen and dining room were used together, and the size of these rooms has been partially increased from the original module in different ways for each case. The above findings suggest that Utbangkkeokeum houses of Cheongju city have been spatially changed while maintaining the previous lifestyle.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.8-16
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• 2023

In this work, we report basic performance test results of a lab-scale three phase alternative current (AC) arc plasma torch system for plasma gas reforming applications. The suggested system primarily consists of three graphite electrodes inclined at 12.5° to the central axis, a 𝞥 150 mm cylindrical gas path and a three phase-60 Hz AC power supply. At air flow rate of 50 Lpm and arc currents of 100-175 A, test results revealed that plasma resistances were decreasing from 1.08 Ω to 0.53 Ω with the increase of plasma power from 9.3 kW to 13.8 kW, causing the decrease of power factor and increase of the line voltages. However, the injected air can be heated quickly up to the temperatures of >1,200℃ when injecting AC arc plasma powers of >10 kW.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.135-147
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• 2015

Recent underground common utility tunnels are underground facilities for jointly accommodating more than 2 kinds of air-conditioning and heating facilities, vacuum dust collector, information processing cables as well as electricity, telecommunications, waterworks, city gas, sewerage system required when citizens live their daily lives and facilities responsible for the central function of the country but it is difficult to cope with fire accidents quickly and hard to enter into common utility tunnels to extinguish a fire due to toxic gases and smoke generated when various cables are burnt. Thus, in the event of a fire, not only the nerve center of the country is paralyzed such as significant property damage and loss of communication etc. but citizen inconveniences are caused. Therefore, noticing that most fires break out by a short circuit due to electrical works and degradation contact due to combustible cables as the main causes of fires in domestic and foreign common utility tunnels fire cases that have occurred so far, the purpose of this paper is to scientifically analyze the behavior of a fire by producing the model of actual common utility tunnels and reproducing the fire. A fire experiment was conducted in a state that line type fixed temperature detector, fire door, connection deluge set and ventilation equipment are installed in underground common utility tunnels and transmission power distribution cables are coated with fire proof paints in a certain section and heating pipes are fire proof covered. As a result, in the case of Type II, the maximum temperature was measured as $932^{\circ}C$ and line type fixed temperature detector displayed the fire location exactly in the receiver at a constant temperature. And transmission power distribution cables painted with fire proof paints in a certain section, the case of Type III, were found not to be fire resistant and fire proof covered heating pipes to be fire resistant for about 30 minutes. Also, fire simulation was carried out by entering fire load during a real fire test and as a result, the maximum temperature is $943^{\circ}C$, almost identical with $932^{\circ}C$ during a real fire test. Therefore, it is considered that fire behaviour can be predicted by conducting fire simulation only with common utility tunnels fire load and result values of heat release rate, height of the smoke layer, concentration of O2, CO, CO2 etc. obtained by simulation are determined to be applied as the values during a real fire experiment. In the future, it is expected that more reliable information on domestic underground common utility tunnels fire accidents can be provided and it will contribute to construction and maintenance repair effectively and systematically by analyzing and accumulating experimental data on domestic underground common utility tunnels fire accidents built in this study and fire cases continuously every year and complementing laws and regulations and administration manuals etc.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.90-94
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• 2014

Environmental qualification (EQ) for safety-related equipment is required to ensure that those equipment will perform their required function even under the harsh environment conditions arising from design basis accident in the nuclear power plant. As a part of EQ program, the room temperature analysis in case of a loss of Heating, Ventilation, and Air Conditioning(HVAC) system was carried out to ensure the operability of the safety-related equipment of a nuclear power plant randomly chosen among the Korean nuclear power plants. In this paper, this analysis was performed in the conservative perspective using GOTHIC code. The room temperature analysis includes selecting the rooms in which the safety related equipment are located but not supported by safety related HVAC and determining the temperature of the selected rooms. Target rooms for the analysis consist of W229/W237 (Aux. feedwater pump room), W232 (Aux. feedwater tank room) and W230 (Equipment passageway). The results showed the temperature range from $43^{\circ}C$ to $83^{\circ}C$, in 72 hours after a loss of HVAC. Those values are far below of generic EQ temperature($171^{\circ}C$). Therefore, it is satisfied with EQ requirement of temperature limits on safety related equipment.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.201-203
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• 2017

There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi-wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.427-434
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• 2008

Processing of collagen from yellowfin tuna (Thunnus albacares) abdominal skins was optimized by response surface methodology and central composite design. The values of independent variables at optimal conditions were NaOH concentration: 0.5 N, NaOH treatment time: 36.2 hr, pepsin concentration: 1:4.9 ratio (0.245%, w/v), and digestion time: 48.1 hr, respectively. The collagen content estimated under optimal conditions was 33.1%, and the actual experimental collagen content was 32.3%. Physicochemical properties of collagen from yellowfin tuna abdominal skin were investigated by amino acids analysis, SDS-PAGE, FT-IR, viscosity and denaturation temperature. Amino acids content of the collagen was 21.0%. SDS-PAGE pattern of the collagen showed two different $\alpha$-chain (${\alpha}_1$- and ${\alpha}_2$- chain), $\beta$-component and $\gamma$-component. The spectrum of FT-IR of the collagen showed wavenumber at 3,434, 1,650, 1,542 and $1,235\;cm^{-1}$ representing the regions of amide A, I, II and III, respectively. Relative viscosity of the collagen decreased continuously on heating up to $32^{\circ}C$, and the rate of decrease was retarded in the temperature range of $35-50^{\circ}C$. Denaturation temperature (Td) of the collagen solution (0.06%, w/v) was $31^{\circ}C$ and was lower than calf skin collagen ($35^{\circ}C$).

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.211-221
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• 2003

At Aspo hard rock laboratory in Sweden, an in-situ heater experiment called "$\"{A}"{s}"{p}"{o}$ Pillar Stability Experiment (APSE)" is prepared to assess capability to predict spatting and stability in a rock mass between deposition holes for radioactive waste. To Predict reasonably fracturing process at rock pillar under a planned configuration before testing, a boundary element code FRACOD has been applied for modelling. The code has been improved to simulate explicitly fracture evolution both at rock boundaries and in intact rocks. A new inverse stress reconstruction technique using boundary element has been also developed to transfer stress field by excavation and thermal loading into the FRACOD model. This article presents the results from predictive modelling far the planned in-situ test condition. Excavation induced stresses might cause slight fracturing in the pillar walls. Typical shear fractures have been initiated and propagated near central pillar walls during 120 days of heating, but overall rock mass remained stable under the considered configuration. The effects of pre-existing joints and properties of fractures are also discussed. It is found from the results that FRACOD can properly model essential rock spatting and propagation at deep tunnels and boreholes.at deep tunnels and boreholes.