• New & Renewable Energy
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• v.16 no.1
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• pp.41-46
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• 2020

The share of agrophotovoltaics in the "renewable energy 3020", which is the Korean government policy for revitalizing new and renewable energy, is increasing gradually. In this study, the distribution of solar radiation received by crops growing on virtual farmland under a range of conditions, such as module height, module angle, shading ratio, and module type, was quantified and analyzed using an Ecotect program, which allows insolation analysis during the period from spring to fall. As the module angle increases, transmissive modules increase the amount of solar radiation delivered to the lower farmland. In addition, the difference between 3x12 Cell Type and 4x9 Cells Type, which are types of photovoltaic modules used in practice, was found to be small. The analysis results can be used as a design standard for the future establishment of agrophotovoltaic systems.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.36.1-36.1
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• 2016

This is a presentation of the paper published as Kimm et al. 2016, ApJ, 823, 52. We investigate the formation of metal-poor globular clusters (GCs) at the center of two dark matter halos with $Mhalo{\sim}4{\times}107Msun$ at z>10 using cosmological radiation-hydrodynamics simulations. We find that very compact (${\leq}1$ pc) and massive (${\sim}6{\times}105Msun$) clusters form rapidly when pristine gas collapses isothermally with the aid of efficient $Ly{\alpha}$ emission during the transition from molecular-cooling halos to atomic-cooling halos. Because the local free-fall time of dense star-forming gas is very short (${\ll}1Myr$), a large fraction of the collapsed gas is turned into stars before stellar feedback processes blow out the gas and shut down star formation. Although the early stage of star formation is limited to a small region of the central star-forming disk, we find that the disk quickly fragments due to metal enrichment from supernovae. Sub-clusters formed in the fragmented clouds eventually merge with the main cluster at the center. The simulated clusters closely resemble the local GCs in mass and size but show a metallicity spread that is much wider than found in the local GCs. We discuss a role of pre-enrichment by Pop III and II stars as a potential solution to the latter issue. Although not without shortcomings, it is encouraging that a naive blind (not tuned) cosmological simulation presents a possible channel for the formation of at least some massive GCs.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.194-199
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• 1998

This research was aimed to figure out the trend of dust diffusion at open pit limestone mine for assessing the environmental impacts on the high voltage power transmission line. It is rather easy to assess the dust generation and size distribution of limestone dust at the blasting site, but it is very hard to assess the expected area of dust diffusion and amount of dust fall by the distances from the dust source. In this research, a 3-dimensional fluid dynamic simulation software (3D-Flow) was used for analysing the above mentioned matters to assess the impacts to the insulators on the transmission tower by the blasting dust. It was verfied that the 3D-Flow is reliable tool for simulating dust movement, and the limestone dust is not much hazardous to the power transmission line.

• Current Optics and Photonics
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• v.1 no.5
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• pp.529-537
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• 2017

We explored how changes in blood vessel compliance affected the systolic rise time (SRT) of the maximum blood pressure (BP) peak wave and the diastolic fall time (DFT) of the minimal BP peak wave, compared to photoplethysmograpic (PPG) parameters, using a two-compartment, second-order, arterial Windkessel model. We employed earlier two-compartment Windkessel models and the components thereof to construct equivalent blood vessel circuits, and reproduced BP waveforms using PSpice technology. The SRT and DFT values were obtained via circuit simulation, considering variations in compliance (the dominant influence on blood vessel parameters attributable to BP changes). And then performed regression analysis to identify how compliance affected the SRT and DFT. We compared the SRTs and DFTs of BP waves to the PPG values by reference to BP changes in each subject. We confirmed that the time-shift propensities of BP waves and the PPG data were highly consistent. However, the time shifts differed significantly among subjects. These simulation and experimental results allowed us to construct an initial trend curve of individual BP peak time (measured via wrist PPG evaluations at three arm positions) that facilitated accurate individual BP estimations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.6
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• pp.515-520
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• 2012

A daylighting system includes three parts; light collector, light transformer and light distributor. A DBLP(Double blind light pipe) daylighting system consists of a double blind light collector, a mirror duct type light transformer and a prism film light pipe distributor. The double blinds for a light collection are used to track the sun's altitude and azimuth movements throughout the day. Behind both sets of blinds is the light transformer, which is based on a rectangular cone shaped light duct. The light transformer was designed to efficiently deliver the light into the light pipe within a 30 degree radial spread for the efficient light into the distributor. In this study, DBLP system efficiency was simulated, evaluated and optimized by Tracepro as a popular ray trace light design simulation program. The results indicated that DBLP system efficiency evaluated a maximum 22.4% in case of Spring/Fall season solar noon time. While the overall average system efficiency in the morning and afternoon is evaluated about 10%.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.826-831
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• 2006

In this paper, we discussed the energy performance of underfloor air distribution(UFAD) and overhead air distribution system according to outdoor air intake rates in a office building. For this, the laboratory(S lab.) is selected for measuring the thermal environments of UFAD system and overhead system. Based on the measured data, the TRNSYS simulation is used to evaluate the energy performance of UFAD system and the overhead system according to outdoor air intake rates. By increasing outdoor air intake rates from required outdoor air intake rates(100CMH) to maximum air intake rates, the energy savings of UFAD system comparing with overhead system are varied $15%{\sim}25.6%$ in summer, $12.8%{\sim}19%$ in fall/spring and not varied in winter(8%). As results of simulations on stratification height and cooling set temperature, the lower the stratification height and the higher cooling set temperature, the larger cooling energy savings of UFAD comparing with overhead system according to outdoor air intake rates.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.771-781
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• 2021

The purpose of this study is to identify major drivers of Myanmar's long-term economic growth and draw implications to implement development policies. This study investigated Myanmar, as the country is the most recently opened economy in Southeast Asia. This study conducted simulation analysis based on scenarios by applying World Bank's Long-Term Growth Model, Penn World Table 9.1, and World Development Indicator data. This study makes extensive use of LTGM and the LTGM-TFP extension to improve the validity of models for data calibration. This study confirms the validity of the model with data calibration and specifies scenarios for simulation analyses by setting the growth trajectory of Vietnam due to common geographical, political, and economic conditions. Main findings include that Myanmar's economic growth rate will continue to fall below 3% in 2040 without proper improvement of growth drivers. The results of this study also provide that total factor productivity growth and female labor participation are key factors for Myanmar's long-term economic growth. This study advises policymakers in Myanmar to strengthen human capital, which is crucial for total factor productivity growth in Myanmar's context and directly affects economic growth. Further, labor market policies to promote female labor participation is important to sustain economic growth.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.115-125
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• 2021

Simulation-based hull form optimization is a typical HEB (high-dimensional, expensive computationally, black-box) problem. Conventional optimization algorithms easily fall into the "curse of dimensionality" when dealing with HEB problems. A recently proposed Cross-Entropy (CE) optimization algorithm is an advanced stochastic optimization algorithm based on a probability model, which has the potential to deal with high-dimensional optimization problems. Currently, the CE algorithm is still in the theoretical research stage and rarely applied to actual engineering optimization. One reason is that the Monte Carlo (MC) method is used to estimate the high-dimensional integrals in parameter update, leading to a large sample size. This paper proposes an improved CE algorithm based on quasi-Monte Carlo (QMC) estimation using high-dimensional truncated Sobol subsequence, referred to as the QMC-CE algorithm. The optimization performance of the proposed algorithm is better than that of the original CE algorithm. With a set of identical control parameters, the tests on six standard test functions and a hull form optimization problem show that the proposed algorithm not only has faster convergence but can also apply to complex simulation optimization problems.

• East Asian Economic Review
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• v.26 no.4
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• pp.305-336
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• 2022

This study applied the macro-micro simulation model (i.e., what-if analysis) to investigate the impact of transport related to the Belt and Road Initiative (BRI) on poverty and income inequality in Laos. We selected Laos as a case study of a developing country. We used the standard GTAP model with the GTAP database (version 10) for the macrosimulation, whereas we used the household model with the latest Lao household data from 2019 for the microsimulation. Our findings revealed that the output of the Lao economy was anticipated to increase by up to 0.3%, while the poverty rate was anticipated to decline from 17.0% to 15.7%. However, there would be winners and losers in industries and groups of households in different areas. In particular, rich households with a comparative socioeconomic advantage, such as in education, engagement in nonfarm business, and infrastructure access, would mostly gain benefits; consequently, this would lead to higher inequality in Laos. Therefore, the inequality index (i.e., the Gini coefficient) would increase from 41.2 to 60.1. After a simulation of BRI transport, we also found that some nonpoor households, which are mainly associated with farm activities and lower educational levels, would fall into poverty.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.421-425
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• 2007

The application of 3 dimensional virtual reality continuously pursues 3 dimensional system implementation in geographical information system, and is applied and studied in various fields like visualization, simulation, and 3 dimensional analysis. Orthoimage produced to construct basic data of virtual city is evaluated in accuracy, to fall in allowable error of the specification of image map generation. In this paper, 3 dimensional virtual city is constructed and evaluated around Bucheon University using 3 dimensional virtual reality technique and digital photogrammetry. Consequently, the constructed 3 dimensional virtual city around Bucheon University can visualize 3 dimensional reality, to help making decision. It can be substituted for existed 2 dimensional GIS in public and private sectors, and be helpful to decision makers.