• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.11
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• pp.13-24
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• 2019

The history of tall buildings begins in 1853with the development of elevators. After the Industrial Revolution of the 18th century, the development of high-rise buildings will be carried out in earnest as a means to efficiently use the limited land of cities. The development, which began around Chicago, extended over a long period of time to Asia, maximizing the high competition. However, in the 2000s, not only was it high due to the development of construction and digital technology, but it also became competitive in eco-friendly elements and unstructured forms. High-rise building plans that have gained elemental and morphological diversity are completed by the interrelationships of various plans. Among them, it is important that the core plan has a reasonable approach from the initial planning stage as the basis for the vertical copper plan linking vertically-intensive functions. The cores should be designed to be clear and adequately responsive to changes in the shape of the building. This study aims to provide designers with a reasonable understanding of core planning by identifying core characteristics of irregular high-rise. In particular, we want to analyze the shape of the ground layer core and the relationship between the area and components of the ground layer core. The analysis results are as follows, classified according to the type or use of the building. Of the atypical forms composed of double bending, the TAPER-Curve and TWIST forms are the most distributed, and the plane and core shapes of the ground floor are the most commonly used. Based on the analysis of the validity of the ground floor cores by shape of the cores, the most commonly used forms for core shapes in the planning of the atypical high-rise are square, circular and Oval, and the most efficient oval cores and relatively inefficient ones when planned.

• Korean Journal of Construction Engineering and Management
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• v.23 no.2
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• pp.24-32
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• 2022

In Korea, the productivity of the construction industry is evaluated at a very low level, and the utilization of the elemental technology of the Fourth Industrial Revolution is also very low compared to other industries. In order to solve this problematic situation, it is necessary to identify the demand for technology improvement in the specialty construction industry that is directly in charge of construction in projects. Therefore, this study aims to investigate improving construction competitiveness and the demand for technology improvement in Korea's specialty construction industry. First, the concept and status of classification of the specialized construction industry were identified, and a questionnaire was organized. Second, a survey was conducted on experts construction experts, and the demand for technical improvement of the specialty construction industry was derived by applying AHP and cluster analysis. The results of this study will serve as a practical reference for policy development, R&D direction, and technology development roadmap to enhance construction competitiveness in the future, and ultimately will help to present directions to improve the construction competitiveness of the construction industry.

• Journal of Conservation Science
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• v.37 no.6
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• pp.767-777
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• 2021

This study analyzed the microstructures and chemical composition of three samples of bronze mirrors excavated in the Jeollanam-do region, particularly Goheung and Damyang. Under x-ray irradiation, the analysis results confirmed the broken parts and pores caused by cracks, casting, and corrosion. Major and minor elemental analysis were performed on three mirrors by Scanning electron microscopy (SEM) with Energy dispersive x-ray spectrometry (EDS) and Inductively coupled plasma mass spe ctrome try (ICP-MS). The re sult shows that the bronze mirrors containe d Cu-Sn-Pb alloys. Alpha phase and eutectic phase were observed in the microstructure, confirming that the casting was performed without additional heat treatment. Notably, Three bronze mirrors were made early Three Kingdoms period in Korea.

• Tribology and Lubricants
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• v.37 no.6
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• pp.246-252
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• 2021

Among the engine components of an internal combustion engine, the valve train is a series of systems that supply intake gas to the combustion chamber and operate intake and exhaust valves that discharge exhaust gas. If excessive wear occurs in the valve train system, the suction and exhaust valves do not open and close on time, which leads to abnormal combustion and exhaust gas. In this study, we conduct experiments and analyses on friction and wear characteristics of the valve train system. Moreover, we experimentally study the correlation between the pinball and pinball cap on engine oil lubrication, friction experiment, wear amount analysis, and surface analysis. Specifically, we experiment using Ball on reciprocating tribo-tester and apply commercial engine oil sold on the market engine oil. We construct the experimental conditions for each new oil and oil. Accordingly, the completed specimen was subjected to a confocal microscope to check the wear volume, observe the surface of the specimen, and confirm the elemental components using a scanning microscope (SEM) and an energy dispersion X-ray spectrometer (EDS). Through this experiment, we analyze the friction and wear characteristics of valve train components according to engine oil grade, and the obtained data serve as an effective engine oil management method.

• Clean Technology
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• v.15 no.3
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• pp.186-193
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• 2009

The characteristics of product materials obtained from thermal degradation of low-qualify pyrolytic oil were investigated in this study. The reactants were produced by pyrolysis of mixed plastic waste with film type in a commercial rotary kiln reaction system. The properties of reactants were measured by elemental analysis, calorimetry analysis and SIMDIST analyst. The result of degradation experiments with different reaction temperature programs was discussed through product yields, cumulative yields and production rates of oil products. The multi-step reaction temperature program resulted in higher yields of product oils and lower yields of residues than one-step reaction temperature program. The product characteristics such as production yield and the rate of oil products etc. were influenced by reaction temperature program in the continuous thermal degradation.

• The korean journal of orthodontics
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• v.53 no.2
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• pp.89-98
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• 2023

Objective: This study aimed to compare the mechanical and thermal properties in the anterior and posterior segments of new and retrieved specimens of a commercially available multizone superelastic nickel-titanium (NiTi) archwire. Methods: The following groups of 0.016 × 0.022-inch Bioforce NiTi archwires were compared: a) anterior and b) posterior segments of new specimens and c) anterior and d) posterior segments of retrieved specimens. Six specimens were evaluated in each group, by three-point bending and bend and free recovery tests. Bending moduli (Eb) were calculated. Furthermore, the new specimens were evaluated with scanning electron microscopy/energy-dispersive X-ray spectrometry. A multiple linear regression model with a random intercept at the wire level was applied for data analysis. Results: The forces in the posterior segments or new specimens were higher than those recorded in the anterior segments or retrieved specimens, respectively. Accordingly, Eb also varied. Higher austenite start and austenite finish (Af) temperatures were recorded in the anterior segments. No statistically significant differences were found for these temperatures between retrieved and new wires. The mean elemental composition was (weight percentage): Ni, 52.6 ± 0.5; Ti, 47.4 ± 0.5. Conclusions: The existence of multiple force zones was confirmed in new and retrieved Bioforce archwires. The retrieved archwires demonstrated lower forces during the initial stages of deactivation in three-point bending tests, compared with new specimens. The Af temperature of these archwires may lie higher than the regular intraoral temperature. Even at 2 mm deflections, the forces recorded from these archwires may lie beyond biologically safe limits.

• Analytical Science and Technology
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• v.19 no.1
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• pp.45-49
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• 2006

Drilled sediment core was acquired from Jinheung catchment which was located at Jeollabuk-do Jeongeup city. Elements concentration variation were studied by neutron activation analysis using sediment core by divided 1 cm depth interval. The concentration of major element such as Na, K were increased but Fe was decrease with depth. Minimum elements concentration and particle size were observed at 17 cm depth. This depth was considered 1969 year which was great dry year recorded from the rain fall data and the sedimentation rate was calculated $0.197g{\cdot}cm^{-2}{\cdot}year^{-1}$.

• Journal of Powder Materials
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• v.31 no.1
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• pp.43-49
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• 2024

In this study, a core-shell powder and sintered specimens using a mechanically alloyed (MAed) Ti-Mo powder fabricated through high-energy ball-milling are prepared. Analysis of sintering, microstructure, and mechanical properties confirms the applicability of the powder as a sputtering target material. To optimize the MAed Ti-Mo powder milling process, phase and elemental analyses of the powders are performed according to milling time. The results reveal that 20 h of milling time is the most suitable for the manufacturing process. Subsequently, the MAed Ti-Mo powder and MoO₃ powder are milled using a 3-D mixer and heat-treated for hydrogen reduction to manufacture the core-shell powder. The reduced core-shell powder is transformed to sintered specimens through molding and sintering at 1300 and 1400℃. The sintering properties are analyzed through X-ray diffraction and scanning electron microscopy for phase and porosity analyses. Moreover, the microstructure of the powder is investigated through optical microscopy and electron probe microstructure analysis. The Ti-Mo core-shell sintered specimen is found to possess high density, uniform microstructure, and excellent hardness properties. These results indicate that the Ti-Mo core-shell sintered specimen has excellent sintering properties and is suitable as a sputtering target material.

• Nuclear Engineering and Technology
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• v.22 no.2
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• pp.101-107
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• 1990

The PIXE (Proton Induced X-ray Emission) method is applied to the quantitative analysis of trace elements in tap water, red wine, urine and old black powder samples. Sample irradiations are performed with a 1.202 MeV proton beam from the SNU 1.5-MV Tandem Van de Graaff accelerator, and measurements of X-ray spectra are made by the Si(Li) spectrometer To increase the sensitivity of analysis tap water is preconcentrated by evaporation method. As an internal standard, Ni powder is mixed with black powder sample and yttrium solution is added to the other samples. The analyses of the PIXE spectra are carried out by using the AXIL (Analytical X-ray Analysis by Iterative Least-squares) computer code, in which the routine for least-squares method is based on the Marquardt algorithm. The elements such as Mg, Al, Si, Ti, Fe and Zn are analyzed at sub-ppm levels in the tap water sample. In the red wine sample prepared without preconcentration. the element Ti is detected in the amount of 3ppm. In conclusion, the PIXE method is proved to be appropriate for the analysis of liquid samples by relative measurements using the internal standard. and is expected to be improved by the use of evaluated X-ray production cross-sections and the development of sample preparation techniques.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.216-228
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• 2023

The purpose of this study is to apply the handheld Raman spectrometer to identify the coloring materials used in a large Buddhist painting (of Maitreya Buddha) at Janggoksa Temple through cross-validation with HH-XRF. An in situ investigation was performed together with use of a digital microscope and HH-XRF analysis to verify the properties of pigments used in the gwaebul ("large Buddhist painting") via a non-destructive method. However, the identification of coloring materials composed of light elements and mixed or overlaid pigments is difficult using only non-destructive analysis data. Unlike in situ investigation, laboratory analysis often required samples yet the sampling is restricted to a small quantity due to the cultural heritage characteristic. Thus, it is necessary to develop a non-destructive in situ method to supplement the HH-XRF data. The large Buddhist painting at Janggoksa Temple was painted mainly using white, red, yellow, green, and blue colors. The Raman spectroscopy provides molecular information, while XRF spectroscopy provides information about elemental composition of the pigments. Analysis results identified various coloring materials: inorganic pigment, such as lead white, minium, cinnabar, and orpiment, as well as organic pigment such as gamboge and indigo. Therefore, it is possible to obtain more information for the identification of pigments; organic pigment and mixed or overlaid pigments, while at the same time minimizing the collection sample and simplifying the analysis procedure compared to previously used methods. The results of this study will be used as basic data for the analysis of painting cultural heritage through a non-destructive in situ method in the future.