• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.2
• /
• pp.186-190
• /
• 2023

We studied the various characteristics of Sn-In (wt%) Pb-free solders for photovoltaic ribbon application. The solders near the eutectic composition of Sn₄₈In₅₂ (wt%) existed in InSn₄ and In₃Sn alloy phases, and in In crystal phase, but not in Sn crystal phase. In addition, the InSn₄ phase (γ-alloy) existed separately from the In₃Sn (β-alloy) and the In phase confirmed by an SEM-EDS-mapping. The melting temperature of the eutectic solder of Sn₄₈In₅₂ (wt%) was 119.2℃, and when the Sn content decreased in reference to the eutectic composition, it slightly increased to 121.4℃, but when the Sn content increased, it remained almost constant at 119.1℃. The peel strength of the ribbon plated with the Sn₄₂In₅₈ (wt%) solder was 38.7 N/mm², and it tended to increase when the Sn content increased. The peel strength of the eutectic Sn₄₈In₅₂ (wt%) solder was 53.6 N/mm², and that of the Sn₅₁In₄₉ (wt%) solder was 61.6 N/mm² that was the highest.

• Journal of Conservation Science
• /
• v.33 no.6
• /
• pp.417-429
• /
• 2017

This study aimed at the identification of the black coating materials on the pottery surface and manufacturing technique of black burnished pottery excavated from the Pungnaptoseong, Seoul, which is estimated to be royal fortress of Beakje. According to observation of black coated surface and raw materials, potteries can be divided into two groups. The first group potteries have black inner and black surface with well-selected particles. Second group potteries are black in surface only with unevenly selected particles. Each group seems to represent different manufacturing technique in clay selection, color development timing and method. The black burnished pottery contains high values of CaO, $P_2O_5$, L.O.I. and lower content of $Fe_2O_3$ compared with gray pottery excavated from the same site, which indicates plant ashes were used for coloring the surface of pottery in black. According to the result of SEM-EDS mapping of black burnished pottery, carbon was concentrated on pottery surface, while iron was concentrated on the surface of the gray pottery. Based on XRD analysis, firing temperature of the black burnished potteries were fired low temperature range at 700 to $900^{\circ}C$, and that of the gray potteries ranged from $900^{\circ}C$ to $1000^{\circ}C$.

• Journal of the Society of Disaster Information
• /
• v.13 no.3
• /
• pp.296-304
• /
• 2017

In order to predict about forest fire behavior we constructed a database for combustion characteristic of forest fuels in Samcheok, Gangwon-do and prepared fire risk map and fire risk rating using GIS method in this study. For the mapping autoignition temperature, ignition time, flame duration time, total heat release and total smoke release are selected as the standardized parameters and the overall risk rating was made up of the ignition risk parameters(autoignition temperature, ignition time) and the spread risk parameters(flame duration time, total heat release, total smoke release). Forest fire risk was classified into 5 grades and lower grade of fire risk rating mean to correspond to more dangerous forest fire. As a result, the overall risk rating of Samcheok was classified into three grades from 1 to 3 and Nogok-myeon and Miro-myeon were turned out the most dangerous areas for forest fire. Because of the colony of pine and oak trees and the higher fire loads, the flame propagation will be carried out quickly in these areas.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.13 no.1
• /
• pp.28-34
• /
• 2011

This study was carried out to estimate monthly mean of daily maximum and minimum temperature across North Korea at a 30 m grid spacing for a climatological normal year (1971-2000) and the 4 decadal averages (1971-1980, 1981-1990, 1991-2000, and 2001-2010). A geospatial climate interpolation method, which has been successfully used to produce the so-called 'High-Definition Digital Climate Maps' (HD-DCM), was used in conjunction with the 27 North Korean and 17 South Korean synoptic data. Correction modules including local effects of cold air drainage, thermal belt, ocean, solar irradiance and urban heat island were applied to adjust the synoptic temperature data in addition to the lapse rate correction. According to the final temperature estimates for a normal year, North Korean winter is expected colder than South Korean winter by $7^{\circ}C$ in average, while the spatial mean summer temperature is lower by $3^{\circ}C$ than that for South Korea. Warming trend in North Korea for the recent 40 years (1971-2010) was most remarkable in spring and fall, showing a 7.4% increase in the land area with 15 or higher daily maximum temperature for April.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.14 no.1
• /
• pp.11-18
• /
• 2012

Daily temperature data produced by harmonic analysis of monthly climate summary have been used as an input to plant phenology model. This study was carried out to evaluate the performance of the harmonic based daily temperature data in prediction of major phenological developments and to apply the results in improving decision support for agricultural production in relation to the climate change scenarios. Daily maximum and minimum temperature data for a climatological normal year (Jan. 1 to Dec. 31, 1971-2000) were produced by harmonic analysis of the monthly climate means for Seoul weather station. The data were used as inputs to a thermal time - based phenology model to predict dormancy, budburst, and flowering of Japanese cherry in Seoul. Daily temperature measurements at Seoul station from 1971 to 2000 were used to run the same model and the results were compared with the harmonic data case. Leaving no information on annual variation aside, the harmonic based simulation showed 25 days earlier release from endodormancy, 57 days longer period for maximum cold tolerance, delayed budburst and flowering by 14 and 13 days, respectively, compared with the simulation based on the observed data. As an alternative to the harmonic data, 30 years daily temperature data were generated by a stochastic process (SIMMETEO + WGEN) using climatic summary of Seoul station for 1971-2000. When these data were used to simulate major phenology of Japanese cherry for 30 years, deviations from the results using observed data were much less than the harmonic data case: 6 days earlier dormancy release, 10 days reduction in maximum cold tolerance period, only 3 and 2 days delay in budburst and flowering, respectively. Inter-annual variation in phenological developments was also in accordance with the observed data. If stochastically generated temperature data could be used in agroclimatic mapping and zoning, more reliable and practical aids will be available to climate change adaptation policy or decision makers.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.43 no.1
• /
• pp.11-21
• /
• 2023

This study was conducted to estimate the damage of Whole Crop Corn (WCC; Zea Mays L.) according to abnormal climate using machine learning as the Representative Concentration Pathway (RCP) 4.5 and present the damage through mapping. The collected WCC data was 3,232. The climate data was collected from the Korea Meteorological Administration's meteorological data open portal. The machine learning model used DeepCrossing. The damage was calculated using climate data from the automated synoptic observing system (ASOS, 95 sites) by machine learning. The calculation of damage was the difference between the dry matter yield (DMY)_normal and DMY_abnormal. The normal climate was set as the 40-year of climate data according to the year of WCC data (1978-2017). The level of abnormal climate by temperature and precipitation was set as RCP 4.5 standard. The DMY_normal ranged from 13,845-19,347 kg/ha. The damage of WCC which was differed depending on the region and level of abnormal climate where abnormal temperature and precipitation occurred. The damage of abnormal temperature in 2050 and 2100 ranged from -263 to 360 and -1,023 to 92 kg/ha, respectively. The damage of abnormal precipitation in 2050 and 2100 was ranged from -17 to 2 and -12 to 2 kg/ha, respectively. The maximum damage was 360 kg/ha that the abnormal temperature in 2050. As the average monthly temperature increases, the DMY of WCC tends to increase. The damage calculated through the RCP 4.5 standard was presented as a mapping using QGIS. Although this study applied the scenario in which greenhouse gas reduction was carried out, additional research needs to be conducted applying an RCP scenario in which greenhouse gas reduction is not performed.

• Korean Journal of Digital Imaging in Medicine
• /
• v.15 no.2
• /
• pp.63-68
• /
• 2013

Purpose : The relaxation times of tissue in MRI depend on strength of magnetic field, morphology of nuclear, viscosity, size of molecules and temperature. This study intended to analyze quantitatively that materials' temperatures have effects on T1 and T2 relaxation times without changing of other conditions. Materials and Methods : The equipment was used MAGNETOM SKYRA of 3.0T(SIEMENS, Erlagen, Germany), 32 channel spine coil and Gd-DTPA water concentration phantom. To find out T1 relaxation time, Inversion Recovery Spin Echo sequences were used at 50, 400, 1100, 2500 ms of TI. To find out T2 relaxation time, Multi Echo Spin Echo sequences were used at 30, 60, 90, 120, 150, 180, 210, 240, 270 ms of TE. This experiment was scanned with 5 steps from 25 to $45^{\circ}C$. next, using MRmap(Messroghli, BMC Medical Imaging, 2012) T1 and T2 relaxation times were mapped. on the Piview STAR v5.0(Infinitt, Seoul, Korea) 5 steps were measured as the same ROI, and then mean values were calculated. Correlation between the temperatures and relaxation times were analyzed by SPSS(version 17.0, Chicago, IL, USA). Results : According to increase of temperatures, T1 relaxation times were $214.39{\pm}0.25$, $236.02{\pm}0.87$, $267.47{\pm}0.48$, $299.44{\pm}0.64$, $330.19{\pm}1.72$ ms. T2 relaxation times were $180.17{\pm}0.27$, $197.17{\pm}0.44$, $217.92{\pm}0.39$, $239.89{\pm}0.53$, $257.40{\pm}1.77$ ms. With the correlation analysis, the correlation coefficients of T1 and T2 relaxation times were statistically significant at 0.998 and 0.999 (p< 0.05). Conclusion : T1 and T2 relaxation times are increased as temperature of tissue goes up. In conclusion, we suggest to recognize errors of relaxation time caused local temperature's differences, and consider external factors as well in the quantitative analysis of relaxation time or clinical tests.

• 한국HCI학회:학술대회논문집
• /
• 2008.02a
• /
• pp.813-816
• /
• 2008

In this research we present a method to reconstruct the casting flow simulation result as a 3D model and visualize it on a VR display. First, numerical analysis of heat flow is performed using an existing commercial CAE simulation software. In this process the shape of the original design model is approximated to a regular rectangular grid. The filling ratio and temperature of each voxel are recorded iteratively by predefined number of steps starting from pouring the melted metal into a mold until it is entirely filled. Next we reconstruct the casting by voxels using the simulation result as an input. The color of voxel is determined by mapping the colors to temperature and filling ratio at each step as the flow proceeds. The reconstructed model is visualized on the Projection Table which is one of horizontal-type VR display. It provides active stereoscopic images.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.18-18
• /
• 2010

최근에 건조되는 선박이나 구조물들은 점차 대형화 되어가고, 이에 사용되는 판재들은 점차 고강도 극후판재화 되어가고 있다. 극후판재의 용접성을 향상시키기 위해서는 대입열 용접이 주로 적용되고 있는 실정인데, 30 mmt 이상의 후판을 1 pass로 용접하기 위해서는 EGW(Electro-gas welding) 기법을 사용한다. 대입열 용접은 용접입열(heat input)이 매우 높아 용착금속과 열영향부의 냉각속도가 매우 느려 용접열영향부에서 특히 fusion line 근처의 열영향부는 결정립 조대화 및 취약한 미세조직을 형성함으로서 저온인성을 크게 저하시키고, 연화 현상(softening effect)을 발생시켜 강도가 저하되는 문제점이 주로 발생하였다. 하지만 이런 문제점을 해결하기 위해 대입열용접에 사용된는 강재의 미세조직을 제어하여 AlN, TiN, $TiO_2$ 등의 석출물을 이용한 용접열영향부의 저온인성을 향상시켰다. 이러한 문제점이 발생하는 대입열용접에서 저온인성 시험은 주로 fuison line + 1, 2mm에서 수행한다. 하지만 대입열 용접시 용착금속의 냉각속도도 매우 느리기 때문에 용착금속의 위치에 따라 저온 인성 특성이 다르게 나타날 수 있다. 본 연구에서는 EGW 용착금속의 위치에 따른 저온인성 특성을 평가하기 위해 EH-36N, 40mmt 판재를 사용하여 1pole EG 용접 하였다. 용착금속의 저온인성 특성을 평가하기위해 충격 시편의 노치 위치가 fusion line - 2mm와 용접부 중앙을 기준으로 4곳을 선정하여 충격시험을 수행하였다. 또한 용착금속의 경도 분포를 알아보기 위해 micro vickers hardness tester(mitutoyo UR-501)을 사용해 hardness mapping 시험을 하였다. 용착금속의 저온인성은 미세조직과, 산소량에 따라 변화 할 수 있기 때문에 용착금속 위치를 달리하여 미세조직과 산소량도 각각 분석하였다. 용착금속의 저온인성을 향상시킬 수 있는 침상형페라이트와 비금속개재물의 상관관계에 관해 검토 하였다.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.556-559
• /
• 2007

The Urban Environmental Quality (UEQ) indicates a complex and various parameters resulting from both human and natural factors in an urban area. Vegetation, climate, air quality, and the urban infrastructure may interact to produce effects in an urban area. There are relationships among air pollution, vegetation, and degrading environmental the urban heat island (UHI) effect. This study investigates the application of multi-spectral remote sensing data from the Landsat ETM and TM sensors for the mapping of air quality and UHI intensity in Seoul from 2000 to 2006 in fine resolution (30m) using the emissivity-fusion method. The Haze Optimized Transform (HOT) correction approach has been adopted for atmospheric correction on all bands except thermal band. The general UHI values (${\Delta}(T_{urban}-T_{rural})$) are 8.45 (2000), 9.14 (2001), 8.61 (2002), and $8.41^{\circ}C$ (2006), respectively. Although the UHI values are similar during these years, the spatial coverage of "hot" surface temperature (>$24^{\circ}C$) significantly increased from 2000 to 2006 due to the rapid urban development. Furthermore, high correlations between vegetation index and land surface temperature were achieved with a correlation coefficients of 0.85 (2000), 0.81 (2001), 0.84(2002), and 0.89 (2006), respectively. Air quality is shown to be an important factor in the spatial variation of UEQ. Based on the quantifiable fine resolution satellite image parameters, UEQ can promote the understanding of the complex and dynamic factors controlling urban environment.