• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.535-543
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• 2002

In this paper, we propose $\pi$/8 shift 8PSK and trellis-coded $\pi$/8 shift 8PSK-OFDM techniques by applying $\pi$/4 shift QPSK to trellis-coded modulation (TCM), and performing signal set expansion and set partition correspondingly based on phase difference. In our Viterbi decoding algorithm, up to L phase differences from successively received symbols are employed in the new branch metrics. Such sliding multiple symbol detection (SMSD) method provides improved bit-error-rate (BER) performance in the differential detection of the trellis-coded $\pi$/8 shift 8PSK-OFDM signals. The performance improvements are achieved for different communication channels without sacrificing bandwidth and power efficiency. It thus makes the proposed modulation and sliding detection scheme more attractive for power and band-limited systems.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.259-264
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• 2005

Transplantation of cultured chondrocytes can regenerate cartilage tissues in cartilage defects in humans. However, this method requires a long culture period to expand chondrocytes to a large number of cells for transplantation. In addition, chondrocytes may dedifferentiate during long-term culture. These problems can potentially be overcome by the use of undifferentiated or partially developed cartilage precursor cells derived from neonatal cartilage, which, unlike chondrocytes from adult cartilage, have the capacity for rapid in vitro cell expansion and may retain their differentiated phenotype during long-term culture. The purpose of this study was to compare the cell growth rate and phenotypic modulation during in vitro culture between adult chondrocytes and neonatal chondrocytes, and to demonstrate the feasibility of regenerating cartilage tissues in vivo by transplantation of neonatal chondrocytes expanded in vitro and seeded onto polymer scaffolds. When cultured in vitro, chondrocytes isolated from neonatal (immediately postpartum, 2 h of age) rats exhibited much higher growth rate than chondrocytes isolated from adult rats. After 5 days of culture, more neonatal chondrocytes were in the differentiated state than adult chondrocytes. Cultured neonatal chondrocytes were seeded onto biodegradable polymer scaffolds and transplanted into athymic mice's subcutaneous sites. Four weeks after implantation, neonatal chondrocyte-seeded scaffolds formed white cartilaginous tissues. Histological analysis of the implants with hematoxylin and eosin showed mature and well-formed cartilage. Alcian blue/ safranin-O staining and Masson's trichrome staining indicated the presence of highly sulfated glycosarninoglycans and collagen, respectively, both of which are the major extracellular matrices of cartilage. Immunohistochemical analysis showed that the collagen was mainly type II, the major collagen type in cartilage. These results showed that neonatal chondrocytes have potential to be a cell source for cartilage tissue engineering.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.2
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• pp.27-39
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• 1998

The interaction of monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A&M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier.

• Journal of Korea Multimedia Society
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• v.14 no.11
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• pp.1450-1457
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• 2011

Currently most of leak detection monitoring systems use digital maps with paying royalties, and this increases the cost of system construction and financial burdens on local self-governing bodies that manage such systems. Moreover, they have inefficiencies in repair and maintenance, functional expansion, and compatibility with other systems. Thus, this study developed a waterworks pipe network monitoring system that pursues low cost and high efficiency using general-purpose maps on the Internet such as google maps. As this system uses highly compatible free maps, it costs less in construction and its hardware requirements are lower than existing systems, and consequently, overall monitoring performance is enhanced and the cost of construction goes down sharply. This study also proposed a method for pipeline DB construction, which can be started together with the construction of the monitoring system, in order to improve the field applicability of the system.

• Journal of Biomedical Engineering Research
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• v.36 no.3
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• pp.61-68
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• 2015

In this paper, we studied the effects of intersection angles of the flow-foucusing type droplet generation device inlet channel on droplet diameter using numerical simulation modeling. We modeled different intersection angles with a fixed continuous channel width, dispersed channels width, orifices width, and expansion channels width. Numerical simulations were performed using COMSOL Multiphysics$^{(R)}$ to solve the incompressible Navier-Stokes equations for a two-phase flow in various flow-focusing geometries. Modeling results showed that an increase of the intersection angle causes an increase in the modification of the dispersed flow rate ($v^{\prime}{_d}$), and the increase of the modification of the continuous flow rate ($v^{\prime}{_c}$) obstructs the dispersed phase fluid flow, thereby reducing the droplet diameter. However, the droplet diameter did not decrease, even when the intersection angle increased. The droplet diameter decreased when the intersection angle was less than $90^{\circ}$, increased at an intersection angle of $90^{\circ}$, and decreased when the intersection angle was more than $90^{\circ}$. Furthermore, when the intermediate energy deceased, there was a decrease in the droplet diameter when the intersection angle increased. Therefore, variations in the droplet diameter can be used to change the intersection angle and fluid flow rate.

• Journal of KIISE:Software and Applications
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• v.35 no.12
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• pp.741-752
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• 2008

Aspect-Oriented Software Development(AOSD) is the software development methodology that classifies concerns of the system and identifies crosscutting concerns and organizes aspect class, and AOSD has emerged as an important user-oriented software development methodology with high maintainability. However, most of related studies worked on identification and specification and coding of crosscutting concerns. And there have been few studies on slicing technique for tracing method of specified crosscutting concerns. Therefore, this paper proposes slicing technique based on AOSD that identifies and specifies crosscutting concerns through interactive analysis between use cases; also, suggests slicing technique which improves traceability centering on identified crosscutting concerns; applies the aspect-oriented slicing technique to Learning Management System(LMS) for case-study. LMS is a cyber educational system that demands a lot of functional changes and expansion, so it is effective to apply AOSD with high maintainability in developing LMS; and shows the results that compared with related studies by comparing six elements.

• Journal of Labour Economics
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• v.26 no.3
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• pp.115-147
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• 2003

This paper scrutinizes the robustness of the profit-sharing findings first employing an original panel data on the Employee Welfare Fund over the period from 1992 to 2000. In examining the effects of profit-sharing schemes on labor productivity, it controls for simultaneity among profit-sharing, production factors, and productivity using both the two-stage least squares procedure and the lagged variable method. The empirical results show that an increase in firm's contribution to the Employee Welfare Fund is associated with capital-embodied and disembodied productivity enhancement, which is both statistically and economically highly significant. The empirical results are in contrast with predictions of both agency and transaction cost theories, and they imply that more tax benefits and financial incentives for expansion of the Employee Welfare Fund should be required to get productivity gains.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.197-206
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• 2011

The Korean government concentrates on supplying public transit facilities for the mobility handicapped. In other hands, increasing needs of transfer information when the mobility handicapped use transit facilities are substantial but not satisfactory as a whole. This study focuses on evaluating the applicability of developed K-path algorithm to provide user-customized route information that could make an active using of public transit while considering the mobility handicapped preferences. Developed algorithm reflects on requirements considering transfer attributes of the mobility handicapped. Trip attributes of the handicapped are addressed distinguished from handicapped types such as transfer walking time, transfer ratio, facility preferences and etc. This study examines the verification and application of the proposed algorithm that searches the least time K-paths by testing on actual subway networks in Seoul metropolitan areas. It is shown that the K-path algorithm is good enough to provide paths that meet the needs of the mobility handicapped and to be adoptable for the future expansion.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.16-23
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• 2012

Research into the development of high strength (1 GPa) and superior formability, such as total elongation (10%), and stretch-flangeability (50%) in hot-rolled steel was conducted with a thermomechanically controlled hot-rolling process. To improve the overall mechanical properties simultaneously, low-carbon steel using precipitation hardening of Ti-Nb-V multimicroalloying elements was employed. And, ideal microstructural characteristics for the realization of balanced mechanical properties were determined using SEM, EBSD, and TEM analyses. The developed steel, 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V), consisted of ferrite as the matrix phase and second phase of granular bainite with fine carbides (20-50 nm) in both phases. The significant factor of the microstructural characteristics that affect stretch-flangeability was found to be the microstructural homogeneity. The microstructural homogeneity, manifest in such characteristics as low localization of plastic strain and internally stored energy, was identified by grain average misorientation method, analyzed by electron backscattered diffraction (EBSD) and hardness deviation between the phases. In summar, a hot-rolled steel having a composition 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V) demonstrated a tensile strength of 998 MPa, a total elongation of 19%, and a hole expansion ratio of 65%. The most important factors to satisfy the mechanical property were the presence of fine carbides and the microstructural homogeneity, which provided low hardness deviation between the phases.

• Hwankyungkyoyuk
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• v.10 no.2
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• pp.249-268
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• 1997

This Study developed 'Environment Management Integrated Leader(EMIL)' program and evaluated the effect of the Program. The procedure of EMIL program development is as follows; 1) Identifying the training needs Through the interview and discussion with corporate environmental staff and research members, training need are collected. 2) Setting the training objectives 30 objectives are developed through specifying and organizing the training needs. 3) Determining the scopes of the program This program consists of the four scopes. First, the scope of Environmentally Acceptable Management is developed based on ISO 14000 and certification of environmentally friendly business. Second, the scope of Environmentally Acceptable Technology includes air pollution, water pollution, solid wasted management, and pollution prevention. Third, the scope of Integrated Environmental Management focuses on master plan, green marketing, green production, and green accounting. Finally, the scope of Integrated Environmental Concepts focuses on food pollution, environmental activities, and bio-diversity. 4) Selecting the training methods Various methods are used such as off-site visits, exercises, case study, workshop, discussion, role-playing as well as lecture. 5) Implementing the program 49 trainees participated the program for 6weeks. All trainees are working for D. Company Group. 6) Measuring training effects To evaluate the effects of the program, pre-post training evaluation method is used. The results are highly significant at all 4 scopes by the p<.01. This study has some implications in order to establish the environmental management climate. First, the development of new environmental education program for management is necessary. Second, Vast investment are required. Third, more systematic approaches are desired in environmental education. Lastly, more customized program development and implementation to fit in industries will accelerate the expansion of environmental concept.