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Search Results: 1 - 10 of 99881 matches for " Jung I Kang "
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Approximation of fixed points for nonexpansive semigroups in Hilbert spaces
Yonghong Yao, Jung I Kang, Yeol J Cho and Yeong-Cheng Liou
Fixed Point Theory and Applications , 2013, DOI: 10.1186/1687-1812-2013-31
Abstract: MSC: 47H05, 47H10, 47H17.
Electronic Structures and Phonon Spectra in Boronitride Superconductors LaMBN (M= Ni, Pt)
Myung-Chul Jung,Chang-Jong Kang,B. I. Min,K. -W. Lee
Physics , 2013, DOI: 10.1103/PhysRevB.87.144509
Abstract: We have investigated electronic structures and phonon spectra of newly discovered isostructural superconductors LaNiBN (T_c = 4.1 K) and LaPtBN (T_c = 6.7 K). We have found that their electronic structures are substantially three-dimensional, leading to metallicity both in NiB (PtB) and the intervening LaN layers. Our ab initio phonon calculations show that almost all phonon modes contribute to the electron-phonon coupling (EPC) mechanism, reflecting that both layers are involved in the superconductivity. For LaNiBN, we obtain an EPC strength of \lambda = 0.52 and a logarithmically averaged characteristic phonon frequency of \omega_{log} = 376 K, leading to T_c = 3.9 K. Compared with the Ni B_{1g} mode in LaNiBN, the Pt B_{1g} mode in LaPtBN is reduced by ~70%, leading to a slightly enhanced \lambda = 0.56 and an ~20 % reduced \omega_{log}. The estimated T_c is 5.4 K for LaPtBN, in good agreement with the experiment. We do not find any indication of magnetic instability for either LaNiBN or LaPtBN, which implies that both systems are EPC mediated superconductors. Further, we have found an interesting trend of monotonic increase of T_c with respect to the boron height in the NiB (PtB) layer of both borocarbide and boronitride superconductors, which suggests a possible way to enhance T_c in these systems.
An Experimental Study for Construction of Emergency Spillway in Daechung Dam  [PDF]
Hongkoo Yeo, Joongu Kang, Sanghwa Jung
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.49072
Abstract: Recently, the flood frequently happened by several effects, such as El Nino et al., is the meteorological accident to attack the stability of dam. Hence, it was necessary to increase the stability of existing dam and dam design criteria were reinforced with probable maximum flood. This study was conducted in order to install the emergency spillway in Daechung Dam. Daechung Dam is located in the upper course of Guem River, in the middle of Korea, near a Sobak mountain range. The stream length and area of Daechung Dam are each about 401 km, about 9886 km2. According to the Report of new training project in Daechung Dam published in 2004 year, Maximum flood water level of Daechung Dam was calculated EL. 84.18 m increased of previous maximum flood water level (EL. 83 m). The aim of this study is to make an alternative plan on problems predicted by analysis of experimental data which is the results on the hydraulic model on dam structures. Analysis of experimental results was classified dam structures, such as approach channel, spillway, energy dissipater and stream, by design conditions.
Flow Characteristic Variations on Groyne Types for Aquatic Habitats  [PDF]
Joongu Kang, Hongkoo Yeo, Sanghwa Jung
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.411103
Abstract: The field formed by groyne has the function of aquatic habitats for the underwater biology. The characteristic of groyne field occurring around downstream of groyne depends on groyne type and shape. Thus to maximize the function of groyne, it needs to understand the flow characteristic around groyne. In this study, experiment model test was conducted in recirculation zone located in downstream of groyne. Groyne types for experiment are three: permeable, impermeable and inclined crest groyne. LSPIV (Large Scale Particle Image Velocimetry) is used to measure flow field around the groyne and it revealed flow characteristic in recirculation zone at each case. In order to estimate the aquatic habitats of groyne fields, critical swimming speed of major fleshwater fish in Korea was compared with the variation of velocity distribution in groyne fields. From the results, the rate of velocity decreases in groyne fields, V/Vapp were measured to be 0 to 0.5 and the results can be fundamental data which are used to estimate the aquatic habitable function of groyne.
Ho-jung KANG
天津体育学院学报 , 2003,
Abstract: 体育利润的增长,体育参与的增加,职业体育的流行和不同体育项目的商业化,使体育在社会中的重要性大大增加。这也导致了体育产业的发展。在韩国,自1997年以来政府官员和学者们越来越频繁地使用“体育产业政策”这个词。该文认同体育产业是一个有发展前景的产业,其包括三个亚产业:体育用品业、体育场地、设施业和体育服务业。该文旨在分析政策的变迁和韩国体育产业现状,并提出发展体育产业的战略决策。体育产业促进政策开始制定于第1个国家体育促进总体计划(1993―1997)准备时。在第3个国家体育促进总体计划(2003―2007)中,政策的导向包括与建设体育文本和体育网络信息有关的基础结构。1999年,韩国国民体育估算产值约为90.4亿美元,占韩国国内生产总值的2.48%。全部体育场地、设施产业产值为25.99亿美元。很明显,体育场地、设施业是体育产业中最大的组成部分,其产值占体育产业总值的43%强。体育用品业中的竞技体育鞋袜和服装产值为17.6亿美元。体育服务市场估算为15.3亿美元,占体育产业总值的17%。体育用品促进政策包括制定不同的贷款项目,合作计划和提高质量计划。自1997年以后,针对体育场地、设施业的特殊贷款项目开始实施...
Experimental Study for the Determination of the Material Diameter of the Riprap Bed Protection  [PDF]
Joongu Kang, Sanghwa Jung, DOongsub Rhee, Hongkoo Yeo
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.310123
Abstract: Bed protection in apron downstream was installed to use riprap or gabion mattress. In the case of bed protection using riprap, the decision on the riprap diameter is very important because riprap diameter means the capacity to withstand the flow. Initial formulas for the decision on the riprap diameter applied velocity and weight as main factors. Since the main factors gradually expanded to depth, bed slope, and turbulence intensity, decision formulas for the riprap diameter were detailed. Because turbulence intensity was considered to be a main factor of the formula, the decision formulas for the riprap diameter could be expanded to apply to bed protection around hydraulic structures. Escarameia and May conducted a study on the riprap diameter of a strong turbulence area around the downstream of hydraulic structures. For the formula of Escarameia and May, the basis of the formula was the Izbash type, and the main factor was turbulence intensity. This study was an experimental study for deciding the riprap diameter installed around apron downstream and was based on the study results of Escarameia and May. The experiment measured the velocity upon change of discharge and riprap diameter to the installed weir model and analyzed the correlation of threshold velocity by diameter. The experimental formula in this study expanded the turbulence intensity limits of the Escarameia and May formula and increased application to turbulence intensity in weir downstream.
Case Study: Hydraulic Model Experiment to Analyze the Hydraulic Features for Installing Floating Islands  [PDF]
Sanghwa Jung, Joongu Kang, Il Hong, Hongkoo Yeo
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.42012
Abstract: The viewpoint of a river is changing as people regard the river as water-friendly space where they can enjoy and share the space beyond the simple purpose of flood control alongside the improving social level. The floating islands installation was planned featuring three islands. The river’s flow and channel stability could be changed when new structures are built in a river. Hence an analysis of the hydraulic characteristic changes should need. The hydraulic model experiment in this study sought to review the impacts of the floating islands installation on the safety of flood control and stability of river channel. This study analyzed the hydraulic features affecting the surrounding stability when installing floating islands and proposed stable floating islands layout in terms of hydraulics based on the experiment results.
Habitat Evaluation on Scour Hole Downflow Low Drop Structure Types Using Large-Scale Experiment  [PDF]
Joongu Kang, Changsung Kim, Sanghwa Jung, Hongkoo Yeo
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.49071
Abstract: This study sought to review whether large-scale experimentation can apply to actual rivers concerning the effect of topographical change by scour in the downstream area of natural-type low drop structures on the fish habitat. The large-scale applicability experiment performed in this study installed low drop structures as the study object within the experiment channel and precisely surveyed topography in the downstream area of drop structures along with the hydraulic amount including water level and flow velocity under certain flow conditions. Based on topographical data acquired through the survey after the experiment ended, this study reviewed the change of suitability index and difference of weighted usable area by performing 2D habitat simulation. Ultimately, through the habitat simulation results in cases of considering and not considering scour in the downstream area of drop structures, this study analyzed the effects of topographical change in actual rivers on the habitat.
Anomalous microwave conductivity coherence peak in c-axis MgB2 thin film
B. B. Jin,T. Dahm,A. I. Gubin,Eun-Mi Choi,Hyun Jung Kim,Sung-IK Lee,W. N. Kang,N. Klein
Physics , 2003, DOI: 10.1103/PhysRevLett.91.127006
Abstract: The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by bandstructure calculations. In addition, the observation of a coherence peak indicates that the pi-band is in the dirty limit and dominates the total conductivity of our films
Phonon structure in I-V characteristic of MgB$_{2}$ point-contacts
I. K. Yanson,V. V. Fisun,N. L. Bobrov,Yu. G. Naidyuk,W. N. Kang,Eun-Mi Choi,Hyun-Jung Kim,Sung-Ik Lee
Physics , 2002, DOI: 10.1103/PhysRevB.67.024517
Abstract: The search of the phonon structure at the above-gap energies was carried out for $d^{2}V/dI^{2}(V)$ spectra of MgB$_{2}$ point contacts with a normal metal. The two-band model is assumed not only for the gap structure in $dV/dI(V)$-characteristics, but also for phonons in $d^{2}V/dI^{2}(V)$ point-contact spectra, with up to the maximum lattice vibration energy. Since the current is carried mostly by charges of 3D-band, whereas the strong electron-phonon interaction occurs in 2D-band, we observe the phonon peculiarities due to ''proximity'' effect in {\it k}-space, which depends on the variation of interband coupling through the elastic scattering.
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