• The Korean Journal of Physiology and Pharmacology
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• 제14권6호
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• pp.441-447
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• 2010

B13, a ceramide analogue, is a ceramidase inhibitor and induces apoptosis to give potent anticancer activity. A series of thiourea B13 analogues was evaluated for their in vitro cytotoxic activities against human renal cancer Caki-2 and leukemic cancer HL-60 in the MTT assay. Some compounds (12, 15, and 16) showed stronger cytotoxicity than B13 and C6-ceramide against both tumor cell lines, and compound (12) gave the most potent activity with $IC_{50}$ values of 36 and $9\;{\mu}M$, respectively. Molecular modeling of thiourea B13 analogues was carried out by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). We obtained highly reliable and predictive CoMSIA models with cross-validated $q^2$ values of 0.707 and 0.753 and CoMSIA contour maps to show the structural requirements for potent activity. These data suggest that the amide group of B13 could be replaced by thiourea, that the stereochemistry of 1,3-propandiol may not be essential for activity and that long alkyl chains increase cytotoxicity.

• International Journal of Computer Science & Network Security
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• 제24권4호
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• pp.141-146
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• 2024

A local area network (LAN) is a computer network within a small geographical area such as a home, school, computer laboratory, office building or group of buildings. A LAN is composed of interconnected workstations and personal computers which are each capable of accessing and sharing data and devices, such as printers, scanners and data storage devices, anywhere on the LAN. LANs are characterized by higher communication and data transfer rates and the lack of any need for leased communication lines. Communication between remote parties can be achieved through a process called Networking, involving the connection of computers, media and networking devices. When we talk about networks, we need to keep in mind three concepts, distributed processing, network criteria and network structure. The purpose of this Network is to design a Local Area Network (LAN) for a BAEC (Bangladesh Atomic Energy Commission) Head Quarter and implement security measures to protect network resources and system services. To do so, we will deal with the physical and logical design of a LAN. The goal of this Network is to examine of the Local Area Network set up for a BAEC HQ and build a secure LAN system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1579-1602
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• 2020

In the design of production system, buffer capacity allocation is a major step. Through polymorphism analysis of production capacity and production capability, this paper investigates a buffer allocation optimization problem aiming at the multi-stage production line including unreliable machines, which is concerned with maximizing the system theoretical production rate and minimizing the system state entropy for a certain amount of buffers simultaneously. Stochastic process analysis is employed to establish Markov models for repairable modular machines. Considering the complex structure, an improved vector UGF (Universal Generating Function) technique and composition operators are introduced to construct the system model. Then the measures to assess the system's multi-state reliability and structural complexity are given. Based on system theoretical production rate and system state entropy, mathematical model for buffer capacity optimization is built and optimized by a specific genetic algorithm. The feasibility and effectiveness of the proposed method is verified by an application of an engine head production line.

• Preventive Nutrition and Food Science
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• 제13권1호
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• pp.28-32
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• 2008

Water vapor sorption by sodium alginate-based films may result in swelling and conformational changes in the molecular structure and affecting the water vapor barrier properties. Sodium alginate film specimens were dried in a vacuum freeze dryer and their moisture content was determined by an air-oven method. The water vapor absorption was determined at two different levels of water activities (0.727 and 0.995) and at three temperatures (10, 20, and $30^{\circ}C$), and kinetics were analyzed using a simple empirical model. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs 1/t. It was found that water vapor absorption kinetics of sodium alginate films were accurately described by a simple empirical model. The rate of water vapor sorption increased with increase in temperature and it showed temperature dependency following the Arrhenius equation. The activation energies varied from 49.18$\sim$149.55 kJ/mol depending on the relative humidity.

• Journal of Biosystems Engineering
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• 제31권4호
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• pp.305-314
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• 2006

Precision farming has been known as an environment friendly farming technology. This study was conducted to develop a variable-rate granule fertilizer applicator as an attempt for introducing the precision farming technologies to rice cultivation in Korea. In this paper, concept design process and manufacturing of prototype variable rate granule applicator was reported. For concept design, some design guide lines were selected. Based on the design guide line and some engineering knowledge, concept design was conducted. The designed prototype granule applicator was mounted at the rear of riding type cultivator for paddy field and had a 10m wide boom structure with pneumatic conveying and application system as well as 1GPS receiver, 1 granule hopper, 12 blow heads, 2 metering devices and 1 controller. The fertilizer applicator had 942 ka of weight, 740m of ground clearance and 1,117mm of center of gravity from the ground. The applicator was designed to be able to $34{\sim}428kg/ha$ of granule at $0.2{\sim}0.8m/s$ of fertilizer working speed.

• The Journal of Asian Finance, Economics and Business
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• 제8권7호
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• pp.525-532
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• 2021

This study examines the association between a firm's business strategy and audit report lags. This study employs 5,072 firm-year observations from 2015 to 2019. Our sample comprises all of the firms listed on the Korea Composite Stock Price Index (KOSPI) market and Korea Securities Dealers Automated Quotation (KOSDAQ). We perform OLS regression analysis to test our hypothesis. The OLS regression analysis was conducted through the SAS and STATA programs. We find that business strategy is positively associated with audit report lags. Especially, we find that defender firms are negatively associated with audit report lags. The findings of this study suggest that prospector-like firms would increase their performance uncertainty as well as audit risk. Therefore, prospector-like firms interfere with the efficient audit procedures of auditors. On the other hand, our findings indicate that defender-like firms would decrease their performance uncertainty as well as an audit risk because they focus on simple product lines and cost-efficiency. For this reason, auditors will be able to carry out the audit procedures much more easily. Our results present that a prospector-like business strategy degrades audit effectiveness as it exacerbates a company's financial risk, willingness to accept uncertainty, and the complexity of organizational structure.

• 유통과학연구
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• 제19권7호
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• pp.19-27
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• 2021

Purpose: Former research has argued that organizations in distribution channels face several issues to make a better team-based system. The purpose of the present research is to measure between employee's job performance and three major issues which disturb a solid team system. Research design, data and methodology: Scant past studies are available to guide for team practitioners which elements should be eliminated to improve team performance. To achieve this goal, the present authors obtained 267 US workers in distribution channels and conducted ANOVA test to measure the relationship between three team issues (Free-rider, Trust, and Communication) and job performance. Results: Our statistical findings clearly suggests that there was a statistically recognizable difference at the significance level of probability between the mean value of employees' job performance and three major issues, showing the high degree of job performance can be occurred by eliminating three major team issues. Conclusions: Therefore, the present research concludes that it is necessary that team-based management in the supply chain should focus on removing free-rider issues and also adopt open communication lines to overcome team-building challenges due to communication. Above all else, the ability to increase trust can be enhanced via task delegation and more team members' engagement.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2279-2284
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• 2011

기존의 수지상 배전계통은 사고 등에 대한 설비보호 및 전력공급 신뢰도 향상을 위하여 과전류보호협조방식을 채택하고 있다. 국내 배전계통의 경우, 그 보호방식 협조체계는 배전용변전소 동일 변압기 동일 모선에서 다수의 배전선이 각각 CB(변전소 차단기)를 통하여 인출되어 각 배전선로 이하에서 사고발생시 고장전류를 검출하여 해당 CB를 차단하도록 되어있다. 그러나, 이와 같은 보호방식을 채용하고 있는 배전계통에 분산전원이 도입될 경우 변전소 인출차단기의 차단용량은 영향을 받게 되므로 충분한 검토가 필요하다. 본 논문에서는 분산전원 도입시, 국내 배전용 변전소의 인출차단기에 대한 차단용량을 초과하지 않는 보호협조방법을 제시하고, 이를 PSCAD-EMTDC 계통해석 S/W Tool에 의하여 모의하여 검증하였다.

• 천문학회지
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• 제38권2호
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• pp.279-282
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• 2005

We report the millimeter-wave radio observations of molecular cloud cores in Taurus. The observed line is the $N_2H^+$ emission at 93 GHz, which is known to be less affected by molecular depletion. We have compared starless (IRAS-less) cores with star-forming cores. We found that there is no large difference between starless and star-forming cores, in core radius, linewidth, core mass, and radial intensity profile. Our result is in contrast with the result obtained by using a popular molecular line, in which starless cores are larger and less condensed. We suggest that different results mainly come from whether the employed molecular line is affected by depletion or not. We made a virial analysis, and found that both starless and star-forming cores are not far from the critical equilibrium state, in Taurus. Together with the fact that Taurus cores are almost thermally supported, we conclude that starless Taurus cores evolve to star formation without dissipating turbulence. The critical equilibrium state in the virial analysis corresponds to the critical Bonnor-Ebert sphere in the Bonnor-Ebert analysis (Nakano 1998). It is suggested that the initial condition of the molecular cloud cores/globules for star formation is close to the critical equilibrium state/critical Bonnor-Ebert sphere, in the low-mass star forming region.

• The Korean Journal of Physiology and Pharmacology
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• 제8권6호
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• pp.345-349
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• 2004

Heat shock ($43^{\circ}C$ for 60 minutes) is sufficient to induce apoptosis in a wide number of cell lines. In this study, we asked whether DNA strand breaks are responsible for this phenomenon. Using the highly sensitive comet assay for DNA damage detection, we were unable to demonstrate DNA breaks immediately after heat shock in Raji human Iymphoid cells. It showed that DNA breaks were not necessary for hyperthermic apoptosis, since its activity is indicative of DNA lesions. Here, we present a suggestion that a protein(s) is the major target for heat shock apoptosis. We firstly found glycerol, which reportedly stabilizes protein structure, showed a protective effect in Raji cells against hyperthermic apoptosis. In addition, quercetin, which modulates transcription of the heat shock protein family members, enhanced apoptotic death induced by hyperthermia. Furthermore, Raji cells are protected by a pre-mild heat treatment prior to the killing dose of heat shock.