• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.62-69
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• 2016

Current guidance considers that uniaxially loaded specimen with a deep crack is used for the determination of the ductile-to-brittle transition temperature. However, reactor pressure vessel is under biaxial loading in real and the existence of deep crack is not probable through periodic in-service-inspection. The elastic stress intensity factor and the elastic-plastic J-integral which were used for crack-tip stress field and fracture mechanics assessment parameters. The difference of the loading condition and crack geometry can significantly influence on these parameters. Thus, a constraint effect caused by differences between standard specimens and a real structure can over/underestimate the fracture toughness, and it affects the results of the structural integrity assessment, consequentially. The present paper investigates the constraint effects by evaluating the master curve $T_0$ reference temperature of PCVN (Pre-cracked Charpy V-Notch) and small scale cruciform specimens which was designed to simulate biaxial loading condition with shallow crack through the fracture toughness tests and 3-dimensional elastic-plastic finite element analyses. Based on the finite element analysis results, the fracture toughness values of a small scale cruciform specimen were estimated, and the geometry-dependent factors of the cruciform specimen considered in the present study were determined. Finally, the transferability of the test results of these specimens was discussed.

• Journal of the Korean housing association
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• v.18 no.1
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• pp.27-34
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• 2007

The purpose of this study is to examine the characteristics of the plan of fishing village house in the Shikoku district. The research was carried out by field survey and measurement of the traditional house and street system in Higashimachi area of Tomoura. The results of this study are as follows. The traditional house of Higashimachi area is to be taking the plan of Machiya form that is the residence form of a city without being related a fishing village. And the street system is as orderly comparatively as a city. This is not the thing as that is surprised when we think the fact that Higashimachi area has maintained close relation historically with Kyoto, Osaka, etc. However, as for the house of Higashimachi area, the scale is smaller in comparison with Machiya, there is a fundamental difference in terms of the house for the exclusive use of residence. Machiya is the dual constitution of business space and life space. To it the house of Higashimachi area is doing the unitary constitution. Mise is the original opening device (a kind of the front door fitting) of traditional house of Higashimachi area and has the functions that complement narrow space and of offer community space. Finally, the traditional house in this area is equipped with all the residence functions of necessary minimums, although the scale residence is small. It is said that this is the case of a 'small residence' in a Japanese residence.

• The Journal of Sustainable Design and Educational Environment Research
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• v.14 no.1
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• pp.10-21
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• 2015

Due to the impact of birth rate, the school age population decreases year by year, and as a result, the Ministry of Education conducts the layout adjustment for middle and primary schools and cancels substantial rural schools. Nearly half of the cancelled and idle schools are not applied till now. Combining the practical demand of local residents, it is quite necessary to make use of the idle schools effectively again. Consequently, field investigation is conducted for the architectural status of 28 idle schools in Pingle County of Guilin, Guangxi, and detail investigation and analysis has been carried out for the different scales of schools from various aspects, including the covered area, traffic, building construction, space composition, degree of aging, etc. The investigation result shows that small teaching schools are remote, being small in scale, single in space and serious in aging. Complete primary schools are close to the villages and towns, being large in scale, abundant in space, and well preserved. The teaching schools are between the previous two types. Meanwhile, it is generally convenient in traffic, and good in structure. It can provide fundamental data for the future utilization and study.

• Journal of the Korean Institute of Rural Architecture
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• v.23 no.4
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• pp.1-12
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• 2021

Recently, the use of unmanned aerial vehicles (UAVs) is increasing in the field of land information acquisition and terrain exploration through high-altitude aerial photography. High-altitude aerial photography is suitable for large-scale geographic information collection, but has the disadvantage that it is difficult to accurately collect small-scale geographic information. Therefore, this study used low-altitude UAV to monitor changes in small rural spaces around rural resources, and the results are as follows. First, the low-altitude aerial imagery had a very high spatial resolution, so it was effective in reading and analyzing topographic features. Second, an area with a large number of aerial images and a complex topography had a large amount of point clouds to be extracted, and the number of point clouds affects the three-dimensional quality of rural space. Third, 3D mapping technology using point cloud is effective for monitoring rural space and rural resources because it enables observation and comparison of parts that cannot be read from general aerial images. In this study, the possibility of rural space analysis of low-altitude UAV was verified through aerial photography and analysis, and the effect of 3D mapping on rural space monitoring was visually analyzed. If data acquired by low-altitude UAV are used in various forms such as GIS analysis and topographic map production it is expected to be used as basic data for rural planning to maintain and preserve the rural environment.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.31.1-31.1
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• 2008

While some observations in the geomagnetic tail region supported electrons could be accelerated by reconnection processes, we still need more observation data to confirm electron acceleration in this region. Because most acceleration processes accompany strong pitch angle diffusion, if the electrons were accelerated in this region, strong energetic electron precipitation should be observed near earth on aurora oval. Even though there are several low altitude satellites observing electron precipitation, intense and small scale precipitation events have not been identified successfully. In this presentation, we will show an observation of strong energetic electron precipitation that might be analyzed by relativistic electron acceleration in the confined region. This event was observed by low altitude Korean STSAT-1, where intense several hundred keV electron precipitation was seen simultaneously with 10 keV electrons during storm time. In addition, we observed large magnetic field fluctuations and an ionospheric plasma depletion with FUV aurora emissions. Our observation implies relativistic electrons can be generated in the small area where Fermi acceleration might work.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.287-296
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• 2011

This study examines the influences of correlated color temperature and illuminance on visual perception and temporary mood sensation in a small office. Field measurements and surveys were conducted in a full-scale mock-up model. Twenty subjects participated in the survey under six lighting conditions formed by three color temperature and two illuminance levels. Results indicate that 4000 K color temperature was effective to mitigate glare sensation from light source. Lamps with low color temperature such as 2700 K was not recommended for office lighting since they are likely to caused glare and visual discomfort. Preferred color temperature was 4000 K and 6500 K for 750 lx and 500 lx target illuminance respectively. The increase of illuminance was not an effective contributor to improve mood perception. The illuminance should be lower than 500 lx to achieve good mood, but the illuminance level in office space should be considered with visual performance simultaneously. This study suggests that fluorescent lighting fixtures with 4000 K lamps would be usefully used for office lighting since they formed friendly conditions for better visual performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.553-561
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• 2010

This study examines the influence of light variation on visual responses in a small office space where a daylight dimming control system is applied. Field measurements and survey were performed in a full-scale mocked-up small office space under clear sky day conditions. Maximum fluctuation range for desktop was 133.5 lx and it just happened once for entire monitoring period. For the majority of time, the fluctuation range did not exceed 50 lx, which did not cause visual discomfort to subjects. The daylight dimming control system successfully kept required illuminance levels for an office environment when desktop illuminance by daylight ranged up to 300 lx. The most serious contributor to the sensation of glare was direct daylight through window. The dimming of electric light was not a significant contributor to visual discomfort for the subjects under clear sky day conditions. Visual comfort was significantly influenced by the sensation of glare, feeling for visual stimulation and distraction, and required illuminance level.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.386-390
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• 2016

Water aeration is an effective water treatment process, which involves the injection of air or air-water mixture into water treatment reservoir commonly through pipes. The main purpose of water aeration is to maintain healthy levels of dissolved oxygen (DO), which is the most important water quality factor. The pipes' operating conditions are important for controlling the efficiency and effectiveness of aeration process. Many studies have been conducted on two-phase flows in pipes, however, there are a few studies to deal with small s ale in millimeter. The main objective of this study is to perform 2-dimensional two-phase simulations inside various straight pipes using the computational fluid dynamic (CFD) OpenFOAM (Open source Field Operation And Manipulation) tools to examine the influence of flow patterns on bubble size, which is closely related to DO concentration in a water body. The both flow regimes, laminar and turbulence, have been considered in this study. For turbulence, Reynolds-averaged Navier-Stokes (RANS) has been applied. The coalescence and breakage of bubbles caused by random collisions and turbulent eddies, respectively, are considered in this research. Sauter mean bubble diameter and water velocity are compared against experimental data. The simulation results are in good agreement with the experimental measurements.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.13-23
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• 2022

The purpose of this study was to analyze the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes, which are mainly situated along rivers where water resources are easy to secure. The groundwater observation network in Miryang, Gyeongsangnam-do, located downstream of the Nakdong River, was selected for the study area. We classified the groundwater monitoring well into the greenhouse (riverside) and field cultivation areas (plain and mountain) to compare the groundwater impact of water curtain cultivation in the greenhouse complex. The characteristics of groundwater level changes classified by terrain type were analyzed using the observed data. Riverside wells have significant permeability coefficients and are close to rivers, so they are greatly affected by river flow and precipitation changes so that water level shows a specific pattern of annual changes. Most plain wells do not show a constant annual change, but observation wells near small rivers and small-scale greenhouse cultivation areas sometimes show annual and daily changes in which the water level drops during winter. Compared to other observation wells, mountain wells do not show significant yearly changes in water level and show general characteristics of bedrock aquifer well with a low permeability coefficient.

• Journal of Information Science Theory and Practice
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• v.10 no.spc
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• pp.12-24
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• 2022

This study attempted to investigate changes in collaboration structure for each stage of national Research and Development (R&D) in the artificial intelligence (AI) field through analysis of a co-author network for papers written under national R&D projects. For this, author information was extracted from national R&D outcomes in AI from 2014 to 2019. For such R&D outcomes, NTIS (National Science & Technology Information Service) information from the KISTI (Korea Institute of Science and Technology Information) was utilized. In research collaboration in AI, power function structure, in which research efforts are led by some influential researchers, is found. In other words, less than 30 percent is linked to the largest cluster, and a segmented network pattern in which small groups are primarily developed is observed. This means a large research group with high connectivity and a small group are connected with each other, and a sporadic link is found. However, the largest cluster grew larger and denser over time, which means that as research became more intensified, new researchers joined a mainstream network, expanding a scope of collaboration. Such research intensification has expanded the scale of a collaborative researcher group and increased the number of large studies. Instead of maintaining conventional collaborative relationships, in addition, the number of new researchers has risen, forming new relationships over time.