• Natural Product Sciences
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• v.15 no.3
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• pp.173-179
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• 2009

To determine the cytotoxic activity of natural compounds, chromatographic separation of the hexanesoluble fraction from the fruiting body of Ganoderma lucidum led to the isolation of four steroids and one triterpenoid. They were identified as ergosterol peroxide (1), stella sterol (2), ergosterol (3), 9(11)-dehydroergostrol peroxide (4), and ganodermanontriol (5) based on spectroscopic evidence and physicochemical properties. These compounds were examined for their cytotoxic activity against HL-60, MCF-7, and LLC cancer cell lines. Ganodermanontriol (5) showed cytotoxic activity with IC$_{50}$ values of 24.8 and 22.9 $\mu$g/mL against HL-60 and MCF-7 cancer cell lines, respectively, whereas compounds 1 - 4 were inactive.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.268-270
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• 1999

국내외를 불문하고 네트워크 환경의 대중화로 인한 그 수요의 증가로 네트워크 기술 자체에 대한 이해는 물론이며, 네트워크에 연결된 수 많은 장비들에 대한 트래픽 문제의 해결과 효율적인 관리가 필수적이다. 중앙집중형 NMS는 네트워크에 연결된 수 많은 NE들을 구성하고 제어하기 위하여 대부분의 네트워크에서 SNMP를 이용하고 있으나, Manager와 Agent 들의 계속적인 Polling과 정보교환은 오히려 네트웍 트래픽을 증가시키는 역할을 하고 있다. 그리하여 최근에 SNMPv2를 이용한 분산형 망관리 시스템이 도입되고 있다. 따라서 본 논문은 망 관리 시스템의 내부적 부하인 SNMP의 네트워크 트래픽을 중앙집중형과 분산형 망관리 시스템으로 구분하여 시스템 다이내믹스 모델링 기법과 시스템 다이내믹스 시뮬레이션 툴인 STELLA를 이용하여 네트워크 트래픽 패턴을 분석하여, 망 관리 시스템 구축시 적절한 요소의 가감을 통해 네트워크 트래픽을 줄이고, 효율적인 망관리 시스템을 구축하는데 그 목적이 있다.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.64.3-64.3
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• 2019

A bright post-breakout emission was detected for a Type Ic supernova (SN Ic) LSQ14efd, which was among the first for SNe Ic. To explain the early-time light curve and color evolution, the effects of the circumstellar medium (CSM) are investigated. Four main parameters, CSM mass, CSM radius, nickel distribution, and explosion energy, are systematically explored in multi-group radiation hydrodynamics simulations, STELLA. Matching the model light curves and color evolution with the observation, we could constrain the parameter space and find out the best fit models. Our results imply that the progenitor suffered a strong mass loss shortly before the explosion and had a massive CSM of ~0.1 M_⊙.

• Macromolecular Research
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• v.17 no.9
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• pp.638-645
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• 2009

We report the effect of the amount of the mesoporous material, SBA-15, on the basic traits of fully aliphatic polyimides (API). For this purpose, water soluble, fully aliphatic poly(amic acid) triethyl amine salts ($PAA_{(s)}$) were prepared and mixed with various amounts of SBA-15. Fully aliphatic polyimide hybrid composites containing the SBA 15-type mesoporous silica were synthesized successfully from bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and alicyclic diamine, 4,4'-methylene bis(2-methylcyclohexylamine). The structure of the hybrid composites was confirmed by IR spectroscopic analysis. Scanning electron microscopy revealed the morphology of the compounds. The hybrid composites exhibited good thermal stability, reasonable transparency, and a low dielectric constant.

• Water Engineering Research
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• v.1 no.4
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• pp.267-277
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• 2000

This study reports an examination of the sensitivity of water resources in the Keum River basin to climate change. Assuming a doubling in $CO_2$ concentrations, a cooperative study provided four climate change scenarios for this study, which have been translated into temperature and precipitation scenarios on a basin scale. The study utilized these temperature and precipitation data for each climate change scenario as inputs to the NWS-PC model to generate the corresponding streamflow scenario over the Keum River basin. A reservoir simulation model for the Dae-Chung Dam in the Keum River basin has been developed with an object-oriented simulation environment, STELLA. For each streamflow scenario, the performance of the reservoir was assessed in terms of reliability, resiliency, and vulnerability. Although the simulation results are heavily dependent on the choice of the climate change scenarios, the following conclusions can be clearly concluded: (1) the future streamflow over the Dae-Chung Dam tends to decease during the dry period, which seriously increases competitive water use issues and (2) flood control issues predominate under the $2CO_2$-High case.

• Korean System Dynamics Review
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• v.4 no.2
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• pp.95-130
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• 2003

The purpose of this study is to find what causes make public projects hold off, going beyond the planned deadline and budget. Using System Dynamics(SD) and their derivative Urban Dynamics(UD) models, it intends to analyze major feedback loops based on VENSIM and to simulate them with STELLA software, all of which are interrelated with various causes of project delay. To prevent or ameliorate project delay, first of all it advises to focus on endogenous delaying factors not exogenous ones. These factors either reinforce or balance certain loops in complex causal structure, In the case example on the Cremation Building Project in Cheongju, Residents’ participation demand make negotiation put off and delayed negotiation reinforces administrative-expediency planning in order to observe a time limit, on the other hand, once building consensus, it increase both the level of planning performance and public trust. In the meantime, the real planning process used to neglect residents opinions and manage public grievance only through compensation, he a result of simulation, visible fruit of negotiation in the initial phase seems to be not satisfactory owing to funds and time consumed, but after reaching an mutual agreement among stakeholders, planning performance is effective and strategic than administrative-expediency planning viewed in both financial and time angle. It proposes to devise specific tools schematizing project implementation. In order to upgrade the quality of project management, it recommends for planners to adopt key concepts based on SD/UD diagrams and causal loops, which would contribute to enriching Planning abbots.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.33.1-33.1
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• 2017

Molecular clouds are the sites of stellar birth, and conditions within the clouds control the mode and tempo of star formation. In particular, turbulence largely determines the density and velocity fields, and can affect the gas kinetic temperature as it decays via shocks. However, despite its central role in star formation and many years of study, the properties of turbulence remain poorly understood. As a part of the TRAO key science program, "Mapping turbulent properties of star-forming molecular clouds down to the sonic scale (PI: Jeong-Eun Lee)", we mapped the northern region of the Orion A molecular cloud and the L1688 region of the ${\rho}$ Ophiuchus molecular cloud in 2 sets of lines (13CO 1-0/C18O 1-0 and HCN 1-0/and HCO+ 1-0) using the Taeduk Radio Astronomy Observatory (TRAO) 14-m telescope. We analyze these maps using a python package 'Turbustat', a toolkit which contains 16 different turbulent statistics. We will present the preliminary results of our TRAO observations and various turbulence statistical analyses.

• Knowledge Management Research
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• v.20 no.4
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• pp.57-74
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• 2019

Self-driving technology is changing the paradigm of automotive industry. Since it is imperative to converge this emerging technology with ICT and there is a time lag between securing this emerging technology and occurrence of firm performance, it is difficult to make decisions on technology development. This study investigates patent indicators to understand the impact of self-driving technology on performance of automotive parts companies. We analyze 611 of self-driving technology patents from 2000 to 2016 and the financial performance of 270 small and medium businesses that register the corresponding patents with consideration of up to four years of time lag. Our analysis results show that patents related to self-driving has a positive impact on asset growth of 2 years and sales growth of 3 years in terms of time lag. This study contributes to the literature by analyzing the impact of technology development on the firm performance in case of convergence of the automotive and ICT industries. Additionally, this study provides a role of patent in knowledge management planning through technology development as a practical implication.

• Macromolecular Research
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• v.15 no.2
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• pp.114-128
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• 2007

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants $(\varepsilon)$. The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low $\delta$values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

• Journal of Veterinary Science
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• v.23 no.2
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• pp.30.1-30.6
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• 2022

This report aims to describe the first case of muscular and collagenous choristoma in a dog. A 10-yr-old female mixed-breed dog presented with lateral recumbence, vocalization, positional vertical nystagmus, divergent strabismus, anisocoria, and status epilepticus. The clinical condition evolved to stupor and ultimately, death. Necropsy revealed a white mass causing an irregular increase in the volume of the cerebellar vermis. In histological analysis, a well circumscribed, unencapsulated mass was observed in the cerebellum, consisting of fibers of striated skeletal muscle and collagen fibers, mostly mineralized. Based on the histopathological and histochemical findings, a diagnosis of muscular and collagenous cerebellar choristoma was made.