• Journal of the Korean Applied Science and Technology
• /
• v.21 no.2
• /
• pp.132-139
• /
• 2004

Film forming behavior of monodispersed model composite latexes with particle size of 190 nm, which consist of n-butyl acrylate as a soft phase monomer and methyl methacrylate as a hard phase monomer with different morphology was examined. Five different types of model latexes were used in this study such as random copolymer particle, soft-core/hard-shell particle, hard-core/soft-shell particle, gradient type particle, and mixed type particle. The film forming behavior was evaluated using pseudo on-line measurements of the cumulative weight loss, the UV transmittance, and the tensile fracture energy. Each stages of film formation I, II were not sensitive to the morphology of model latexes, but stage-ill was largely dependent on the morphology of model latexes. The chain mobility of polymer which composed the shell component was found to dominantly determine the behavior of film forming stage-III.

• YAKHAK HOEJI
• /
• v.44 no.6
• /
• pp.595-600
• /
• 2000

Transdermal delivery of ketorolac tromethamine, a potent non-narcotic analgesic, through human cadaver skin was investigated in vitro. A mixture of ethanol/water (40/60) containing 0, 1, 3, 5, and 8 (w/v)% L-menthol were used as a vehicle and penetration enhancer respectively. The permeation of ketorolac through human cadaver skin from saturated drug solution was evaluated at $37^{\circ}C$ with modified Franz diffusion cell. The in vitro skin flux and lag time were $1.23\;{\pm}\;0.11\;{\mu}g/cm^2{\cdot}hr$ and $5.56\;{\pm}\;0.34\;hr$, respectively. The cumulative amount of penetrated ketorolac containing L-menthol in ethanol/water (40/60) binary system was increased by the following order; 3%, 5%, 8%, 1%, 0%, and the lag time was decresed by the following order; 3%, 5%, 8%, 0%, 1%. The results suggested that a potential use of 3% L-methol is an effective penetration enhancer of ketorolac tromethamine through the human cadaver skin.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.5
• /
• pp.271-280
• /
• 2018

This paper presents a framework for developing aftershock fragility curves for reinforced concrete bridges initially damaged by mainshocks. The presented aftershock fragility is a damage-dependent fragility function, which is conditioned on an initial damage state resulting from mainshocks. The presented framework can capture the cumulative damage of as-built bridges due to mainshock-aftershock sequences as well as the reduced vulnerability of bridges repaired with CFRP pier jackets. To achieve this goal, the numerical model of column jackets is firstly presented and then validated using existing experimental data available in literature. A four-span concrete box-girder bridge is selected as a case study to examine the application of the presented framework. The aftershock fragility curves are derived using response data from back-to-back nonlinear dynamic analyses under mainshock-aftershock sequences. The aftershock fragility curves for as-built bridge columns are firstly compared with different levels of initial damage state, and then the post-repair effect of FRP pier jacket is examined through the comparison of aftershock fragility curves for as-built and repaired piers.

• Journal of Korean Society of Forest Science
• /
• v.99 no.2
• /
• pp.204-212
• /
• 2010

This study was performed in 22 unthinned Larix olgensis plantations in northeast China. Data were collected on 95 sample trees of different canopy positions and the diameter at breast height ($d_{1.3}$) ranged from 5.7 cm to 40.2 cm. The individual tree models for the prediction of vertical distribution of live crown, branch and needle biomass were built. Our study showed that the crown, branch and needle biomass distributions were most in the location of 60% crown length. These results were also parallel to previous crown studies. The cumulative relative biomass of live crown, branch and needle were fitted by the sigmoid shape curve and the fitting results were quite well. Meanwhile, we developed the crown ratio and width models. Tree height was the most important predictor for crown ratio model. A negative competition factor, ccf and bas which reflected the effect of suppression on a tree, reduced the crown ratio estimates. The height-diameter ratio was a significant predictor. The higher the height-diameter ratio, the higher crown ratio is. Diameter at breast height is the strongest predictor in crown width model. The models can be used for the planning of harvesting operations, for the selection of feasible harvesting methods, and for the estimation of nutrient removals of different harvesting practices.

• Asia pacific journal of information systems
• /
• v.12 no.1
• /
• pp.87-101
• /
• 2002

In the past few years, many Korean companies have implemented various ERP systems. Despite the enormous efforts and costs, however, there have been doubts about the effectiveness of ERP implementation. The purpose of this study is to identify whether the announcement of ERP implementation affects the market value of the firm. To achieve the research objective, event-study methodology was used assessing the cumulative abnormal returns(CARs) for 33 firms' announcements of ERP investments. Findings of the study are summarized as follows: First, the announcements of ERP implementation have no effect on the firm value though the sign is negative. Second, there is marginally significant difference in the market value of the firm between the first mover of ERP implementation and its followers. In order to figure out any possible reasons of such unexpected results, several investors and fund managers of major investment firms were interviewed. They reached the two agreements that ERP hardly increases the firm value. One was mainly due to the misfit between the foreign business processes built in the ERP systems and Korean firms' traditional business processes. The other was the possibility of financial deterioration caused by substantial costs for ERP implementation.

• Geomechanics and Engineering
• /
• v.4 no.3
• /
• pp.191-208
• /
• 2012

Due to rapid industrialisation, large scale infrastructure development is taking place worldwide. This includes railways, high speed highways, elevated roads etc. To meet the demands of society and industry, many innovative techniques and materials are being developed. In developed nations like USA, Japan etc. for railways applications, new material like geocells, geogrids are being used successfully to enable fast movement of vehicles. The present research work was aimed to develop design methodologies for improvement of grounds subjected to cyclic loads caused by moving vehicles on roads, rail tracks etc. Deformation behavior of ballast under static and cyclic load tests was studied based on square footing test. The paper presents a study of the effect of geo-synthetic reinforcement on the (cumulative) plastic settlement, of point loaded square footing on a thick layer of granular base overlying different compressible bases. The research findings showed that inclusion of geo-synthetics significantly improves the performance of ballasted tracks and reduces the foundation area. If the area is kept same, higher speed trains can be allowed to pass through the same track with insertion of geosynthetics. Similarly, area of machine foundation may also be reduced where geosynthetics is provided in foundation. The model tests results have been validated by numerical modeling, using $FLAC^{3D}$.

• STI Policy Review
• /
• v.5 no.1
• /
• pp.57-74
• /
• 2014

This review organises the fragmented management literature on platform business according to a conceptual map and a meta-theoretical scheme. Since the early 2000s, numerous researchers have examined platform business and two-sided networks with platform business and strategy being an important business innovation model for many industries, creating value primarily by enabling direct interactions. Platforms such as Google or Amazon contain a common set of rules and components in most user transactions. Thirty-two core papers and books on Strategic Management Journal, Industrial Economics and Operation Management-related disciplines are reviewed, with further observations on how cumulative research streams on the platform are carried out independently from each academic perspective. The first of the two arguments in this paper is that because interactive relationships bridge the platform and stakeholders such as end-users and developers, it is crucial for platform companies to be aware of their relationship with stakeholders in order to support and sustainably provide content to their platform. The second is that integrative perspectives are essential due to the low number of interdisciplinary investigations conducted thus far. The paper's final section deals with implications for theory and practice, concluding that integrative studies and interactive relationship studies should be the main research streams in future platform research.

• Journal of Korean Society for Quality Management
• /
• v.25 no.1
• /
• pp.80-99
• /
• 1997

This paper considers designing the simple (2-level) constant-and step-stress ALTs minimizing the asymptotic variance of the maximum likelihood estimator of the accelaeration factor, which is defined as the ratio of the 100qth percentile at use stress to that a specified stress, for items having lognormally-distributed lives. It is assumed that (i) the log-linear relationship exists between the stress and the mean log life, (ii) the standard deviation of the log life is constant, and (iii) the cumulative exposure model holds for the effect of changing stress. For the constant-stress ALT the low stress and the sample proportion allocated to low stress are determined and for two modes of stress loading of step-stress ALTs, the low-to-high and high-to-low, the low stress and the stress change time are determined. For selected values of the design parameters the optimum plans are figured, two modes of step-stress ALTs and the constant-stress ALT are compared to each other, and the effects of the incorrect pre-estimates of the design parameters are investigated.

• Journal of fish pathology
• /
• v.16 no.1
• /
• pp.23-30
• /
• 2003

On September in 1998, a microsporidian infection was recognized in ayu, Plecoglossus altivelis, farmed on Kyongnam province of South Korea. Cumulative mortality was around 10% in 10 days. Infected fish which were piping for air near the surface of the water or in the asphyxic, lethargic condition revealed darkening of body and abdominal distention. Numerous whitish nodules up to 3mm in size were observed throughout most of body organs and tissues including gill, operculum, peritoneal wall and organs. Xenomas were also histologically confirmed in multiple internal organs with the evidences suggesting circulatory disturbance. Based on the morphology of spore and xenoma, and the distribution of xenomas in organs and tissues, this disease was diagnosed to be a microsporidiosis caused by Glugea plecoglossi. The mortality might be deeply related to the local circulatory disturbance by xemonas rather than the mechano-chemical effect of xenomas on adjacent tissues.

• Architectural research
• /
• v.1 no.1
• /
• pp.31-40
• /
• 1999

In this age of "Information", many people consider it a deterrent to information flow to provide a hierarchy with private rooms in a modern office layout. There are others, however, who insist that visual and acoustical privacy are more important than any other design factor in achieving higher productivity. The debate may never end, but the partitioned open plan, which is a new form of the vast open plan, has merits of each concept - open and closed layout. Consequently, office design has dramatically shifted to partitioned open planning, with shorter, temporary walls or partitions, originally intended for increasing privacy and diminishing hierarchy, yet still keeping flexibility in spatial organization. The introduction of low-level partitioned spaces in an office layout, however, produces a complicated lighting design problem. Obviously, accurately predicted daylighting performance data are needed not only for daylighting design but for artificial lighting system design. Scale models of 12 sets of unit partitioned spaces are constructed and extensive scale model measurements of both daylight and reflected sunlight have been performed within an artificial sky simulator. The prototype-building interior is modeled with different partition configurations, each of which is modeled using the different envelope geometry and exterior configurations, and then the variations in interior light levels are estimated. The result indicates that partitioned spaces employed in an open plan of modern offices still offer a large potential for daylighting and energy saving as well. Much of the savings may derive from the cumulative effect of reflected sunlight. Optimal design for building envelope geometry and exterior configuration promises additional savings.