• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.75-83
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• 2015

In the present study, the preliminary results of a large-scale seismic response analysis of a super-high-rise steel frame considering soil-structure interaction are presented. A seismic response analysis under the excitation of the JR Takatori record of the 1995 Hyogoken-Nanbu earthquake is conducted. Precise meshes of a 31-story super-high-rise steel frame and a soil region, which are constructed completely of hexahedral elements, are generated and combined. The parallel large-scale simulation is performed using K computer, which is one of the fastest supercomputers in the world. The results are visualized using an offline rendering code implemented on K computer, and the feasibility of using a very fine mesh of solid elements is investigated. The computation performance of the analysis code on K computer is also presented.

• Electrical & Electronic Materials
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• v.11 no.11
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• pp.37-45
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• 1998

In this paper, present status of super high-efficiency tandem solar cells has been reviewed and key issues for realizing super high-efficiency have also been discussed. In addition, the terretrial R&D activities of tandem cells, in the New Sunshine Program of MITI(Ministry of International Trade and Industry) and NEDO(New Energy and Industrial Technology Development Organization) in Japan are reviewed briefly. The mechanical stacked 3-junction cells of monolithically grown InGaP/GaAs 2-junction cells and InGaAs cells have reached the highest efficiency achieved in Japan of 33.3% at 1-sun AM1.5. This paper also reports high-efficiency InGaP/GaAs 2-junction solar cells with a world-record efficiency of 26.9% at AM0, 28$^{\circ}C$ and radiation damage recovery phenomena of the tandem cell performance due to minority-carrier injection under light illumination or forward bias, which causes defect annealing in InGaP top cells. Future prospects for realizing super-high efficiency and low-cost tandem solar cells are also described.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.111.1-111.1
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• 2015

As an alternative way to get sophisticated nanostructures, atomic force microscopy (AFM) has been used to directly manipulate building primitives. In particular, assembly of metallic nanoparticles(NPs) can provide various structures for making various metamolecules. As far, conventionally made polygonal shaped metallic NPs showed non-uniform distribution in size and shape which limit its study of fundamental properties and practical applications. In here, we optimized conditions for deterministic manipulation of ultra-smooth and super-spherical gold nanoparticles (AuNPs) by AFM. [1] Lowered adhesion force by using platinum-iridium coated AFM tips enabled us to push super-spherical AuNPs in linear motion to pre-programmed position. As a result, uniform and reliable electric/magnetic behaviors of assembled metamolecules were achieved which showed a good agreement with simulation data. Furthermore, visualization of near field for super-spherical AuNPs was also addressed using photosensitive azo-dye polymers. Since the photosensitive azo-dye polymers can directly record the intensity of electric field, optical near field can be mapped without complicated instrumental setup. [2] By controlling embedding depth of AuNPs, we studied electric field of AuNPs in different configuration.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.51-59
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• 2013

It is usual to evaluate the performance of the cool roof by measuring in-site rooftop temperature using thermal infra-red camera. The principal advantage of rooftop thermal infrared image acquired in oblique vantage point of super high-rise building as a remote sensor is to provide, in a cost-effective manner, area-wide information required for a scattered rooftop target with different colors, utilizing wide view angle and multi-temporal data coverage. This research idea was formulated by incorporating the concept of traditional remote sensing into rooftop temperature monitoring. Correlations between infrared image of super high-rise building and in-situ data were investigated to compare rooftop surface temperature for a total of four different rooftop locations. The results of the correlations analyses indicate that the rooftop surface temperature by the infrared images of super high-rise building alone could be explained yielding $R^2$ values of 0.951. The visible permanent record of the oblique thermal infra-red image was quite useful in better understanding the nature and extent of rooftop color that occurs in sampling points. This thermal infrared image acquired in oblique vantage point of super high-rise made it possible to identify area wide patterns of rooftop temperature change subject to many different colors, which cannot be acquired by traditional in-site field sampling. The infrared image of super high-rise building breaks down the usual concept of field sampling established as a conventional cool roof performance evaluation technique.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.277-282
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• 2019

This study was conducted to compare the lap time of high school boys' K-2 1000m final at the $99^{th}$ National Sports Festival with the lap time of the World Championship final held in 2018 and to find an optimal pacing strategy to enhance the performance. The high school boys' average final record was 242.89 seconds, and the top international's 199.58 seconds. There was 43 seconds difference in records and by lap-time it were 9, 12, 9, and 13 seconds behind every 250m. World Championship players used the Super Fast-Even Pacing-Even Pacing-Spurt strategy. The $1^{st}$ to $3^{rd}$ ranked high school boys used Slow-Fast-Super Slow-Super Fast strategy, and $4^{th}$ to $9^{th}$ ranked boys used Fast-Slow-Fast-Slow strategy. The high school boys need to modify their pacing strategies to achieve world-class performance.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.22 no.3
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• pp.91-107
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• 2011

Work is a bibliographic entity serving a key role for the collocation function of catalog. This study analyzed the concept of work, provided a new device to complement conventional FRBR work. The 'prototype' was suggested to enhance the collocation function of catalog, the highest level in FRBR. This study explained the definition, attributes of prototype, and relationships between prototype and work within FRBR model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.655-666
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• 2013

As the capacity of storage devices becomes larger, most users divide them into several logical partitions for convenience of storing and controlling data. Therefore, recovering partitions stably which are artificially hidden or damaged is the most important issue in the perspective of digital forensic. This research suggests partition recovery algorithm that makes stable and effective analysis using characteristics of each file system. This algorithm is available when partition is not distinguishable due to concealment of partition or damage in partition area.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.12-17
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• 2018

A natural cavitation-type high-speed underwater vehicle with solid rocket motor is tested, and its speed and running distance are measured. The outputs from pressure sensors on the surface of the vehicle reveal a pressure-time history reflecting the development of supercavitation. Underwater cameras installed on the wall of the test pool record the entire process from the onset of supercavitation to its full development. CNU-SuperCT, based on two-dimensional inviscid theoretical analysis, is used to simulate test results. Considering CNU-SuperCT does not include the control fins of the vehicle, simulation results agree with test results very well. Additionally, pictures from underwater cameras support the test results.

• Tribology and Lubricants
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• v.33 no.1
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• pp.9-14
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• 2017

This paper presents a rotordynamic analysis and the operation of a power turbine applied to a 250 kW super-critical $CO_2$ cycle. The power turbine consists of a turbine wheel and a shaft supported by two fluid film bearings. We use a tilting pad bearing for the power turbine owing to the high speed operation, and employ copper backing pads to improve the thermal management of the bearing. We conduct a rotordynamic analysis based on the design parameters of the power turbine. The dynamic coefficients of the tilting pad bearings were calculated based on the iso-thermal lubrication theory and turbine wheel was modeled as equivalent inertia. The predicted Cambell diagram showed that there are two critical speeds, namely the conical and bending critical speeds under the rated speed. However, the unbalance response prediction showed that vibration levels are controlled within 10 mm for all speed ranges owing to the high damping ratio of the modes. Additionally, the predicted logarithmic decrement indicates that there is no unstable mode. The power turbine uses compressed air at a temperature of $250^{\circ}C$ in its operation, and we monitor the shaft vibration and temperature of the lubricant during the test. In the steady state, we record a temperature rise of $40^{\circ}C$ between the inlet and outlet lubricant and the measured shaft vibration shows good agreement with the prediction.

• International Journal of High-Rise Buildings
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• v.5 no.3
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• pp.205-211
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• 2016

This paper addresses the key technologies for supertall building construction based on the Lotte World Tower project in Korea. First, the mega-mat foundation construction technologies are shown, including ultra-low heat concrete, heat of hydration control programs, and the logistics plan. Then, high strength concrete technologies of 50~80 MPa are introduced and discussed within the context of the highest pumping record in Korea at 514.25 meters. Structural design concepts of gravity load and lateral force resistance systems are introduced, along with surveying systems using GNSS and temporary installation plans of special heavy equipment like tower cranes, hoists, and high pressure concrete pumps. If it is possible to coordinate these key technologies and others, optimizing for the building's design and construction, supertall building construction can be successfully completed.