• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.90-96
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• 1998

Helical gear system is widely used to transmit heavy duty power with harmonies and silences between parallel shafts. This paper predicts a life with Weibull distribution and estimates a reliability based on recycle principle of helical gear systems. 2-parameter Weibull distribution is generally adopted to estimate the mechanical life and the reliability of most gear systems, because this Weibull distribution is proper to explain a characteristics or a life of parts of gear systems with linearity of probability density data on weibull data sheet. For a high reliability, this paper estimates a number of overhaul times and a number of needed substitutes (exchange attachment,1 or parts) with following renewal theory, One is make an exchange of whole module include failure attachments/parts and second estimating method is only exchange of a failure attachments / parts.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.12
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• pp.1285-1296
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• 2012

This study investigates the effects of changes in price, total consumption expenditures and economic sitations on Korean household demands for clothing and footwear using time-series data. The clothing and footwear category was reclassified as clothing, footwear and clothing services items for the demand analysis. This study utilized the Linearized Almost Ideal Demand System (LAIDS) model to analyze household demand. The results indicate that price and total consumption expenditures are significantly related to Korean household consumption expenditure allocations for clothing and footwear items. The effects of the IMF bailout crisis in 1997 and the global financial crisis in 2008 on household expenditure shares for clothing and footwear items were very weak and statistically insignificant. All the demand elasticities were estimated with respect to total consumption expenditures and prices. Clothing was expenditure elastic (greater than one) and other items were classified as inelastic. All the own price elasticities of demands were negative (other than clothing). Through the estimations of cross price elasticity the relationships between the demands for items and other item prices were evaluated (i.e., substitutes and complements).

• Journal of Life Science
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• v.9 no.1
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• pp.17-21
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• 1999

Chitosan derivitives, a sulfated N-acetylchitosan was synthesized, and artificial skin of sulfated N-acetylchitosan and N-carboxyl butyl chitosan were investigated. Sulfated derivatives of chitosan were analyzed by {TEX}${13}^C${/TEX}-NMR and the structure on N-acetyl chitosan 3,6-O-disulfate were confirmed. Rabbits underwent a midline laparotomy followed either by a bilateral peritoneal sidewall abraison(3.0×1.5cm). The injured surface was then covered with 0.2mm thick sulfated N-acetyl chitosan membrane. Sulfated N-acetyl chitosan membrane was found to reduce postsurgical bleeding after abraison of peritoneal surface treated with sulfated N-acetyl chitosan membrane. Sulfated N-acetyl chitosan implanted rabbit showed quick wound healing than N-carboxybutyl chitosan. With a sterilization procedure of chemical sterilization, sulfated N-acetyl chitosan seem to be better substitutes than N-carboxybutyl chitosan.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.2
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• pp.72-92
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• 1996

식물유, 어유 및 축산 폐기물을 포함한 동식물성 기름은 어느 연료든지 기관의 연료로서 사용 가능하지만, 이들 연료는 점도가 높고, 저휘발성이어서 착화지연기간동안에 가연성혼합기 생성이 어려워 저 NOx이며, 정숙한 운전이 사능할 뿐 아니라 경유정도의 열소비율 및 배기 매연농도로 디젤기관의 대체 연료로서의 충분한 가능성이 있는 연료임을 확인하였다. 그러나, 고점도에 의한 분무 특성의 악화에 기인한 분무입자의 증대로 미연소분에 의한 carbon deposit 및 piston ring stick 등이 문제점으로 지적되었다. 그러나, 이같은 문제점의 해결책으로 경질유와의 혼합, 에스테르 변환 및 연료의 가열등 여러 해결책을 제시하였고, 배기가스분석결과도 양호함을 확인하였다. 이같은 biomass 연료 일종인 식물유가 아무런 변화없이 이용되기 위해서는 고과급화, 단열 및 연소실의 적절한 설계가 필요할 것으로 생각된다. 따라서, 현재의 실황을 생각한다면 기존기관을 특별하게 개조함이 없이 사용을 전제로 할 때 식물유의 이용은 local 에너지로서, 생산, 전환 또는 이용기술의 개발과 동시에 화석에너지의 보충적인 에너지로 고려하는 것이 유효할 것으로 생각된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1459-1467
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• 1997

The current on the thin planar structure as an element of the transversely fed electromagnetically coupled(EMC) microstrip dipole array antenna is obtained by using the integral forms of the finite difference time domain(FDTD) method. This method was applied to calculating the optimum current distribution (Doplh-Tchebyscheff distribution) of each dipole element on the feed line as a function of their offset positions for the narrow main beam width and the side beam level below -20 dB. The current on each dipole substitutes for the electric and magnetic current densities on the virtual surface of the FDTD calculation to express the far field intensity, the calculation time and the computer memeory can be reduced to about 80% and 1.3 Mbyte, respectively. The calculated radiation patterns are compared to the measured values and these are in good agreement.

• Journal of Information Technology Applications and Management
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• v.16 no.3
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• pp.1-15
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• 2009

The paper analyzes a copyright owning firm's incentive to enforce its copyright in the presence of file-sharing networks. I devise a two-period model where a copyright owner sells two different versions of a creator's information good, and show that the firm's overall profits are enhanced by a strategy of differential inter-temporal enforcement of the copyright protection, compared to strategies of no enforcement or full enforcement in both periods. If the firm enforces no copyright protection in the first period, the low-valuation consumers may make and consume copies that are imperfect substitutes for the original information good. If there is a significant increase in the willingness-to-pay of some low-valuation consumers after they experience the information good, the firm can extract the increased consumer surplus by enforcing a positive level of copyright protection in the second period. Social welfare, however, is maximized in the case of no enforcement.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.81-88
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• 1998

The aim of this study is to evaluate several plant extracts with a view to developing UV sunscreen agents. In this study, 150 plant extracts were screened to elucidate their UV spectra using spectrophotometric method. Several plant extracts such as Phellodendron amurense, Morus alba, Rhododendron mucronulatum, Brassica alba have strong absorbency at UVA region (350nm), the suntanning wavelength. And Sophora flavescens, Caesalpinia sapper, Morus alba, Phellodendron amurense, showed absorption plateau value at UVB region (308nm), the erythema action wavelength. These extracts have a good absorbency property as synthetic filter and could be served as substitutes for synthetic UV sunscreen agents.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.341-349
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• 2006

These day, Internet Recruiting needs negotiation of recruiting items. So in this paper, Internet Recruiting Negotiation System(IRNS) proposes multilateral negotiation that substitutes applicants and employers. Previous NSS uses preference value of multi-attribute and sequential negotiation. But proposed IRNS uses parallel negotiation of multi-attribute. parallel negotiation supplies multi-attribute negotiation including single-attribute and results of parallel negotiation. This paper proposes effective negotiation using weight strategy of multi-attribute.

• Asia pacific journal of information systems
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• v.8 no.1
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• pp.65-86
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• 1998

This paper empirically examines relationships among corporate strategy, competitive advantage of information technology(CAIT), and organizational performance. Effects of information technology on the linkage between corporate strategy and performance is investigated and CAIT measures suggested by Sethi and King(1994) as well as Sung(1997) are tested for verification. Research results confirm that information technology provides several traits of strategic advantages such as efficiency, threat, functionality, preemptiveness, and synergy and significantly contributes to corporate performance. CAIT measures developed by Sethi and King show strong reliability and validity, Generally, service industry firms show more strong relationship among CAT strategy, and performance than manufacturing industry firms. The findings reinforce the accepted belief that alignment between corporate strategy and CAT is critical for firms to attain sustainable competitive advantage, subsequently enhances corporate performance and competitive position against rivals, potential entrants, substitutes, suppliers, and buyers.

• The Journal of Korea Robotics Society
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• v.1 no.2
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• pp.197-202
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• 2006

We present the synergy effect of humanoid robot walking down on a slope and support vector machines in this paper. The biped robot architecture is highly suitable for the working in the human environment due to its advantages in obstacle avoidance and ability to be employed as human substitutes. But the complex dynamics in the robot and ground makes robot control difficult. The trajectory of the zero moment point (ZMP) in a biped walking robot is an important criterion used for the balance of the walking robots. The ZMP trajectory as dynamic stability of motion will be handled by support vector machines (SVM). Three kinds of kernels are also employed, and each result from these kernels is compared to one another.