• Polymer Science and Technology
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• v.15 no.2
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• pp.228-233
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• 2004

본 기고부분에서는 레이저 라만 분광법을 이용하여 나노입자에 흡착된 자기조립박막의 구조를 밝히고 응용성을 모색하는 일을 소개하고자 한다 Au 나노입자는 최근 재료과학과 의학 및 생물학에서 그 쓰임의 폭이 넓어지고 있다. 나노입자가 처음 사용된 예들 중에 가장 잘 알려진 것은 고대 로마 시대의 Lycurgus 컵에 기인한다고 한다. 컵 안에 함유된 미량의 은이나 금 나노입자에 의해서 반사했을 때와 투과할 때의 빛깔이 다르게 보이며 이러한 성질은 중세건축물의 스탠드 글라스에 이용되어 왔다. 근대적인 의미에서 Au 콜로이드의 수용액이 작은 미세입자가 분산되어 있다고 생각한 사람은 전기화학의 창시자라 할 수 있는 영국의 Faraday라 할 수 있다.(중략)

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.553-558
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• 2010

To solve the problems of the low combustion activity of Korean anthracite and the abundant loss of unburned carbon in fly ash, pellet coal was fabricated from coal fines and fly ash, and the mixed combustion of coarse coal with the pellet coal was examined in the circulating fluidized bed combustor of a 0.1 MW scale test unit. In the combustion of the raw coal only, the significant amount of coal fines was entrained, resulting in overheat at the top of the combustor. With the coarse coal that most fines were eliminated, however, the combustion temperature was maintained stable. The mixed combustion of coarse and raw coals was also feasible even though it often went unstable. The mixed combustion of the coarse coal with the pellet coal was as stable as the coarse coal combustion, showing a promise that the combustion of the Korean anthracite in commercial circulating fluidized bed boilers could be further enhanced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.305-314
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and a shear connector to combine the two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, a new steel-plate concrete composite (SPCC) beam was developed to reduce the size of the shear connector and improve its workability. The SPCC beam was composed of folded steel plates and concrete, without any shear connector. The folded steel plate was assembled with high strength bolts instead of welding. To improve the workability in field construction, a hat-shaped cap was attached in the junction with the slab. Monotonic two-point load testing was conducted under displacement control mode. The flexural strength of the SPCC beam specimen was calculated to be 76% of that of the complete composite beam by using the plastic stress distribution method and strain compatibility method. The cap acted as the stud and accessory. The synthesis rate could be increased by controlling the gap of the cap, and the bending performance could be evaluated by using the strain fitting method considering the synthesis rate of the SPCC beam.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1397-1406
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• 1996

In this paper, we propose a discrete model of conveyor systems, which is frequently used in flexible manufacturing systems to transfer work-in-process( WIP) between manipulators. In the case where the time required for transferring WIP's between manipulators are greater than that of manufacturing itself, as in many flexible assembly lines, the quantitative model of the transfer systems is needed to analyze the behavior and productivity of the whole manufacturing system. The proposed model is based upon the assumptions that the length of any unit conveyor component is integer multiple of the length of a pallet and hat the transferring speed of the conveyor is constant. Under these assumptions, the observation moments and the length of the conveyor can be quantized. Hence, the state of a conveyor can be represented by two kinds of Boolean variables: one representing the presence of a pallet on each quantize conveyor length and the other representing the mobility of this pallet. The whole conveyor system can be modeling as a network composed of branches and knots based on these two Boolean variables. The proposed modelling method was tested with various conveyor system configurations and showed that the model can be adopted successfully for the simulation of transfer systems and of the piloting of manufacturing processes.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.129-138
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• 1996

The ores of the Bobae mine are mainly composed of sericite and quartz, and with appreciable amount of some other minerals such as andalusite. pyrophyllite, and albite, etc.. Sericite occurs in various a1teration zones having different crystal size and habit. Sericites can be c1assified into two types based on the crystal size; fine-grained and coarse-grained sericite. Fine-grained sericite occurs as an aggregate. Mineralogical characterizations of both types of sericites have been studied with various methods. Lattice parameters of two types of sericites occurred in various alteration zones are almost identical. but b parameter of coarse-grained sericite appears to be slight1y bigger than that of fine-grained aggregates. Average structural formula of fine- and coarse-grained sericite is $K_{1.44}Al_{3.86}(Si_{6.35}Al_{1.65})O_{20}(OH)_4$ and $K_{1.71}Al_{3.82}(Si_{6.20}Al_{1.80})O_{20}(OH)_4$, respectively. Structural formulae of coarse-grained sericites are close to that of muscovite. Infrared spectra show that there is slight distinction between sericites occurred in andalusite-pyrophyllite zone and other subzones. IR spectra of sericites due to Si-O vibration ($540{\sim}530cm^{-1}$) tend to shift to smaller wavenumber side from center to outer alteration zone. All samples have litt1e or no interstratified minerals. and this is demonstrated by Ir and DTA-TG results. It indicates that the Bobae mine is formed at relatively high temperature. That the ratio of quartz to sericite in ores varies greatly indicates that several discontinuous hydrothermal alteration processes have been involved.

• Korean Journal of Ecology and Environment
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• v.53 no.4
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• pp.355-364
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• 2020

This study was carried out to investigated changes in sediments in the eight weir sections of Nakdong River. Sediments were collected and analyzed for Grain Size, Ignition loss, Total Organic Carbon, Total Nitrogen, Total Phosphorus, and Meta. The upstream of the weir was found that fine-grained sediments have repeated increases and decreases. It was found that coarse-grained sediments were being maintained in the downstream part of the weir. The sediments Ignition Loss, Total Organic Carbon, Total Nitrogen, Total Phosphorus are strongly correlated with Grain Size, and these increased at the point where sediments are fine. In the case of metal, the concentration increased across the board, and the correlation with Grain Size, Ignition loss, Total Organic Carbon, Total Nitrogen, and Total Phosphorus was weak. Although there were some sections where fine-grained sediments, organic materials, nutrients, metals increased in the Nakdong River, the overall pollution level is considered weak.

• Management & Information Systems Review
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• v.33 no.4
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• pp.63-75
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• 2014

The paper investigates empirically the determinants of standardization activity at the industry level, focusing on market structure. The enactments or amendments of collective standards is used as the proxy variable for standardization activity. The independent variables, in addition to market structure, are technological opportunity, factor intensity, export ratio, and industry characteristics(assembly). We estimated the logistic regression model(so-called Logit), using the pooling data for 9 Korean industries, including foods, textiles, chemicals, nonmetallic minerals, metals, electronics and electrics, machinery, automobiles, and shipbuilding, over 2006-2009. The empirical finding shows that market structure has no any effects on the enactments or amendments of collective standards in Korea. This might infer that oligopolistic firms devote themselves to de facto standards determined by market rather than de jure standards such as collective standards and Korean Standards(KS). Besides market structure variable, whereas technological opportunity and assembly characteristics are likely to relate positively with the enactments or amendments of collective standards, capital intensity and export ratio have no any relationship with industrial standardization, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.807-815
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• 2008

The brittle failure where is occurred the welding position of column-beam flange of WUF-B connection that consider about a seismic detail possess a superior ductility capacity before Northridge earthquake 1994, require newly study about WUF-B connection. SAC Steel Project suggests a seismic detail to FEMA-350 by supporting of FEMA. It revise shape of weld access holes of WUF-B connection, welding processand welding material etc, In spite of these revision, AISC Seismic Provisions (2005) prescribe WUF-B connection using an only OMF. Recently in Korea, as the earthquake of about seismic intensity 5 occur, the necessity of revision for connection seismic detail comes to the front in Korea and FEMA-350 connection seismic details are going to include in KBC-2008 as it is. In this study, two column-beam connection specimens were marked by using SM490, SN490 built-up H-section, and based on WUF-B detail prescription of FEMA350. The parameters of the specimens are types of steel (SM, SN), and evaluate the capacities of structure and seismic by experiment. Finally we confirm a superior ductility capacity aboutspecimens JB-1 and JB-2, using SM490 and SN490,and these specimens had sufficient OMF and SMF seismic capacity, as indicated in AISC Seismic Provisions (2005).

• Journal of the Korean association of regional geographers
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• v.13 no.1
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• pp.43-53
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• 2007

Rapid geomorphic changes occur in Nakdong River deltaic coast which is composed of deltaic barrier islands and tidal flats. We investigate the pattern of these rapid geomorphic changes by analyzing the distributions of sediment grain size characteristics. The distributions of sediment grain size characteristics analysis is a very efficient method to explain geomorphic changes of deltaic barrier islands. In sediments from Jinwoo Island, Sinja Island, and Doyo Island which are composed of Nakdong River deltaic coast, mean particle size increases to onshore direction and become coarser in tidal inlets. All sediments are very well sorted. Though almost sediments show little negative skewness, several sediments from tidal inlets show negative skewness. These results provide that the stronger and more regular energies affect Nakdong River deltaic coast and make fine sediments selectively move toward tidal inlets. Because of this mechanism, the recurved spits of deltaic barrier islands enlarge.