• Journal of Distribution Science
• /
• v.14 no.1
• /
• pp.29-38
• /
• 2016

Purpose - The purpose of paper is to review and look into the process of port development of each country, and compare with their system of port management. Research design, data and methodology - The methods to be taken is to examine a process of port development in terms of historic and regulated point of views, and each country's port is compared with various port models. Results - China has evolved of port governance into 3 stages, which has lead to almost liberalized port management system in process of privatization slogan. Japan has three stages of port development, and key commitments have been done by local government, rather than national one. Korea has also several stages of port reforms, and national government has been deeply involved in port industry, as well as regional government and port authority in certain areas. Conclusions - whatever port management system each countries has taken, it eventually aims to port productivity in country's port. To adopt most proper port management system may be answer for country to cope with environmental changes around port industry.

• Journal of the Korean housing association
• /
• v.16 no.1
• /
• pp.73-79
• /
• 2005

The ventilation efficiency of apartment housing bathroom has been measured by the flexible's diameter, length, and installation format to the exhaust In. The gas density attenuation method of Tracer Gas Method has been specifically utilized for this measurement. Full size mock-up of apartment housing bathroom, which was approximately $100 m^2$ in size, has been established for the ventilation emciency measurement. In addition, the ventilation efficiency has been studied by the possibility of air-supply In. The diameters of flexible are 100 mm, 125 mm, and 150mm. It also have the length of 1.0m, and 1.5 m. The installation formats are I shape, L shape, and S shape. As a result of this measurement, the flexible which has the highest ventilation efficiency was the one has bigger diameter, short in length, and I shape installation format.

• International Journal of Precision Engineering and Manufacturing
• /
• v.2 no.2
• /
• pp.17-25
• /
• 2001

In this paper, a theoretical study has been made to reduce the residual stress and birefringence in the injection-molded parts. An optimization program has been used to minimize the residual stresses and birefringence calculated from a simulation program. The thermally induced stress has been calculated using a linear viscoelasticity model. The flow stress and birefringence has been calculated using the Leonov's viscoelasticity model. This has been applied to the injection molding of a circular disc and a plate. the optimization has been done either by changing process variables while maintaining the mold temperature constant or by varying the mold-wall temperature with time. This study shows the significant reduction in residual stress and birefringence is possible through the optimization of processing conditions.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.5
• /
• pp.99-107
• /
• 2003

In a winding process, important control specifications include regulation of web tension and velocity. In this research, an adaptive controller has been developed for controlling web tension and velocity in winding processes. For the controller design, the linear quadratic regulator theory has been adopted and a gain-scheduling scheme has been incorporated. A prototype winding system has been constructed, and the controller has been implemented in a real-time PC-based environment. The performance of the closed loop system has been evaluated via simulation and experiments, and it was observed that both the web tension and velocity could be regulated within a small tolerance.

• Tribology and Lubricants
• /
• v.23 no.4
• /
• pp.149-155
• /
• 2007

The CAD model of a elliptical gear for wire cutting has been developed. The rolling contact of pitch ellipses whose rotation axes coincide with their focus has been analyzed, and the perimeter of the pitch ellipse has been divided into equal-length segments by the number of teeth. A master tooth profile, which is a composite curve of circular arcs that represents involute, has been introduced. The elliptical gear has been designed by imposing the master tooth on the divided points of the pitch ellipse, and a full fillet has been achieved between neighbour teeth. Thus, the whole profile of an elliptical gear is a composite curve of arcs only, and consequently NC codes for wire cutting can be easily generated. Furthermore, a computer simulation program is developed to verify the mesh of the elliptical gear.

• Journal of the Korea Furniture Society
• /
• v.26 no.3
• /
• pp.274-285
• /
• 2015

Wood carving has been extremely widely practiced, but survives much less well than the other main materials, being vulnerable to decay, insect damage, and fire. It therefore forms an important hidden element in the art history of many cultures. Even though wood is less durable than either steel or stone, it has been used for a long time due to its usefulness. Wood has a lot of benefits. So people have used wood for materials in houses, trains, cars, bridges, and simple utilities in their ways according to their own religions, climates, and environment they are living in. Nowadays, there are wood products that are made up for its weaknesses and this has made wood be used in variety fields. Moreover, wood has been widely selected materials for sculptures, interior, and also for architecture thanks to its colors and textures. Wood has helped our life more abundant and beautiful.

• Journal of the Korean Society for Heat Treatment
• /
• v.8 no.4
• /
• pp.255-265
• /
• 1995

Stainless steel type 304L has been nitrided in the low pressure (600Pa) and high nitrogen (80% $N_2$+20% $H_2$) environment for 5 hours by the square-wave-pulsed-d.c. plasma as a function of temperature $400{\sim}550^{\circ}C$ and pulsation. At the lower temperature range of $400{\sim}500^{\circ}C$ and at the relatively high ratio of pulse duration to pulse period. "S-phase" has been developed in the form of thin nitrided surface layer which has many cracks, leading to be nearly impossible for the industrial anti-wear and anti-corrosion applications. At the higher temperature up to $550^{\circ}C$ with the increasing ratio of the pulse duration to pulse period up to $50{\mu}s/100{\mu}s$, the nitrided layer, whose growth rate has increased also, has been composed mainly of CrN and $Fe_4N$ phases and has become thick, uniform and nearly crack-free.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1998.06e
• /
• pp.259-262
• /
• 1998

In this paper, we have studied measurement technique for inhomogeneous residual stress using acoustic microscopy with quadrature detector. In experiment, aluminum tensile specimen with the flaw has been made and loaded by Instrone. A spherical typed acoustic transducer of center frequency 5MHz has been used for sending a longitudinal acoustic wave into a stressed specimen. It has been shown in experimental results that the phase has largely changed around the flaw that residual stress has been largely distributed and acoustic microscopy has been used in the field of residual stress measurement.

• Kyungpook Mathematical Journal
• /
• v.55 no.4
• /
• pp.817-826
• /
• 2015

Let R be a commutative ring with total quotient ring K. Each monomorphic R-module endomorphism of a cyclic R-module is an isomorphism if and only if R has Krull dimension 0. Each monomorphic R-module endomorphism of R is an isomorphism if and only if R = K. We say that R has property (${\star}$) if for each nonzero element $a{\in}R$, each monomorphic R-module endomorphism of R/Ra is an isomorphism. If R has property (${\star}$), then each nonzero principal prime ideal of R is a maximal ideal, but the converse is false, even for integral domains of Krull dimension 2. An integral domain R has property (${\star}$) if and only if R has no R-sequence of length 2; the "if" assertion fails in general for non-domain rings R. Each treed domain has property (${\star}$), but the converse is false.

• Journal of Technology Innovation
• /
• v.11 no.2
• /
• pp.219-238
• /
• 2003

This study aims to investigate the impact of wide use of digital technology, in particular, the Internet, on innovation process and corporate strategy in electronics industry. The introduction of digital technology has changed innovation process, business model and organizational structure of the electronics companies. With the wide use of digital technology, the entire value chain of electronics industry from procurement, sales, and marketing to R&D and manufacturing has been restructured. This paper examine how digital technology has changed firms' behaviors in various areas through e-commerce, virtual reality and simulation, the rise of a new type of firm called EMS (Electronics Manufacturing Services), and etc. Amidst these changes building up innovation-friendly organization has emerged as a critical concern for firms. Due to the striking decrease of transaction cost, a network type of organization has proliferated, and a business function turns into a modular organization. As a whole, digital technology has pushed electronics firms into developing their own business model, which takes consideration of standardization of business platform and their core competency.