• The KIPS Transactions:PartC
• /
• v.11C no.6 s.95
• /
• pp.835-842
• /
• 2004

In this paper, we have analyzed the MC-DS/CDMA system with input signal synchronized completely through adjustment of the gain in the PLL loop, by using the hybrid SC/MRC-(2/3) technique, which is said to one of the optimal diversity techniques under the multi-path fading environment, assuming that phase error is defined to the phase difference between the received signal from the multi-path and the reference signal in the PLL of the receiver. Also, assuming that the regarded radio channel model for the mobile communication is subject to the Nakagami-m fading channel, we have developed the expressions and performed the simulation under the consideration of various factor, in the MC/DS-CDMA system with the hybrid SC.MRC-(2/3) diversity method, such as the Nakagami fading index(m), $the\;number\;of\;paths\;(L_p),$ the number of hybrid SC.MRC-(2/3) $diversity\;branches\;(L,\;L_c),$ the number of users (K), the number of subcarriers (U), and the gain in the PLL loop. As a result of the simulation, it has been confirmed that the performance improvement of the system can be achieved by adjusting properly the PLL loop in order for the MC/DS-CDMA system with the hybrid SC/MRC-(2/3) diversity method to receive a fully synchronized signal. And the value of the gain in the PLL loop should exceed 7dB in order for the system to receive the signal with prefect synchronization, even though there might be a slight difference according to the values of the fading index and the spread processing gain of the subcarrier.

• Korean Journal of Construction Engineering and Management
• /
• v.15 no.6
• /
• pp.92-104
• /
• 2014

CM services have been increasingly practiced over the two decades in the Korean construction industry, and recent efforts focus on further development in advanced CM capabilities and expansion to overseas market. However, there has been lack of holistic research to investigate current status and future direction of CM industry in Korea. In this context, the purposes of this study are 1) to analyze current status of Korean CM industry in terms of owners, market, CM firms, contracts, and work scopes, 2) to define different types of CM practices, and 3) to propose growth models for Korean CM firms based on the defined CM project types. An extensive literature review and statistical analysis of 2012 CM contracts were performed in order to analyze the CM status. Based on the analyses, ten different CM types are defined, and growth paths of CM firms are illustrated. Implications and lessons learned during the statistical analysis and workshops are briefly introduced as well.

• Journal of the Korea Concrete Institute
• /
• v.15 no.6
• /
• pp.848-855
• /
• 2003

During concrete placement, the partially distributed load due to the concrete placement paths creates the lateral force in the connection parts of the shore. In order to restrain this lateral force, the nails must be used in the upper and lower connection parts of shores. But, for the convenience of the construction and dismantling of the shores, the workers hardly use the nails. In this case, the connections of shore cannot resist the shear force and rotation. And this situation may cause the collapse of form-shore system. Therefore, contact and spring models for the connection analysis of the form-shore systems are required. If we take into account this construction situation, we need to understand the effects of shear and rotation stiffness according to the several types of connection parts in shores as a case study. This study evaluates the shear and rotation stiffness of the connection parts of shores according to the variations of the lengths, numbers and positions of nails, and then presents the experimental results depending on the end conditions of shores. And, these results can be used as a spring model and critical load evaluation data for the connection analysis of form-shore system.

• Korean Journal of Social Welfare
• /
• v.65 no.2
• /
• pp.335-356
• /
• 2013

Physical resources are central to coping with economic hardships for people in low-income, yet life experiences such as resource loss and gain and their relationships with a sense of well-being received scarce attention. Thus this study investigated levels of loss and gain of physical resources, economic stability and well-being of 254 adults who participated in welfare-to-work programs; correlations and paths among these variables; and direct and indirect effects of economic stability by structural equation modeling. Major results were: first, the levels of resource loss and gain were below a moderate level and the level of gain was significantly higher than the loss level. Second, in the relationships with both economic stability and well-being, resource loss showed negative correlations, while resource gain showed significantly positive correlations. Third, the negative direct effect of resource loss either on the economic stability or on the well-being respectively was significant and the indirect effect on well-being through economic stability was also significant. Finally, the direct effect of resource gain on either economic stability or well-being was significant; and the indirect effect of resource gain on well-being was also significant. Thus in both models for resource loss and gain, the indirect effect of economic stability was significant, which supports partial mediation model. Based on these results, implications for social work practice and research were examined, particularly for enabling social work practice to utilize information regarding resource loss and gain, economic stability, and a sense of well-being that were embedded in the community life of people in low-income.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.3
• /
• pp.170-179
• /
• 1999

The SUS (Signal, Underwater Sound)-OAT experiment was carried out in the Ulleung Basin of the East Sea on 3 June 1997. The SUS-OAT system consisted of aircraft deployed shots as sources and a vertical line array (VLA) tethered by a receiver ship was used to survey a large area where a mesoscale warm eddy appears frequently. The experiment was carried out such that explosive charges set to detonate at 800 ft depth were dropped in a rectangular ($120{\times}120$ km). Sources were a rapidly deployable SUS charge (MK 61 MOD 0), and receiver is a fixed VLA, 90 m in length (150-240 m in receiver depth), composed of 10 elements equally spaced. The reference ray paths are computed by range-dependent acoustic model in canonical ocean based on the historical data. The singular value decomposition (SVD) method is used to obtain the horizontal perturbation of the temperature fields. Horizontal distributions of temperature fields at 150 m and 200 m depth show a weak warm eddy observed by AXBT and the inversely estimated temperature shows similar patterns in terms of the location of the warm eddy. In conclusion, the SUS-OAT experiment has been successful to estimate the position of warm eddy and its temperature field in the East Sea of Korea.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.10
• /
• pp.72-81
• /
• 2011

In this paper, we proposed and designed a novel floating point converter which supports single and double precisions of IEEE754 standard. The proposed convertor supports conversions between floating point number single/double precision and signed fixed point number(32bits/64bits) as well as conversions between signed integer(32bits/64bits) and floating point number single/double precision and conversions between floating point number single and double precisions. We defined a new internal format to convert various input types into one type so that overflow checking could be conducted easily according to range of output types. The internal format is similar to the extended format of floating point double precision defined in IEEE754 2008 standard. This standard specifies that minimum exponent bit-width of the extended format of floating point double precision is 15bits, but 11bits are enough to implement the proposed converting unit. Also, we optimized rounding stage of the convertor unit so that we could make it possible to operate rounding and represent correct negative numbers using an incrementer instead an adder. We designed single cycle data path and 5 cycles data path. After describing the HDL model for two data paths of the convertor, we synthesized them with TSMC 180nm technology library using Synopsys design compiler. Cell area of synthesis result occupies 12,886 gates(2 input NAND gate), and maximum operating frequency is 411MHz.

• Journal of Korean Home Economics Education Association
• /
• v.25 no.3
• /
• pp.105-121
• /
• 2013

This study aimed to investigate the validity and appropriate way of career education according to the integration of home economics subjects, as a way of revitalization of career education in technology and home economics subjects, after the implementation of free semester system. For this goal, the meaning and trend of free semester system, trend of subject-integrated career education, analysis of curriculum in technology home economics education subject, and trend of research about career education in home economics were investigated. The result was as in the following. First, in spite of the ambiguity of the meaning of free semester, the career education will be expanded as the importance of lifelong career education was more and more required. Second, the career paths separated from subjects had problem in its effectiveness, therefore, subject-integrated career education emphasizing on school subjects will become more crucial. Third, it was presented that extracting core achievement standard in subject-integrated career education in technology home economics education according to core achievement standard was critical. For these reasons, the objective and model of career education in home economics education under free semester system were illustrated.

• The Journal of the Korea Contents Association
• /
• v.11 no.8
• /
• pp.187-197
• /
• 2011

There are many researches about effects of consumer innovativeness on the new product adoption behavior. However most of these studies regard this construct as one dimensional concept so that the extant studies suggest very ambiguous results about the relationship between consumer innovativeness and adoption behavior. This study subdivides the construct as cognitive innovativeness and sensory one and suggest these two types of consumer innovativeness affect on the risk perception of the potential adopter differently when the consumer adopt new product. In the empirical research through regression analysis and structure equation model with 217 samples, the study shows the consumer who have high level of cognitive innovativeness are more sensitive to functional risk of new products compared to one who have high level of sensory innovativeness. On the other side, sensory innovative consumer perceive social risk more when they adopt new products than cognitive innovator who have higher level of cognitive innovativeness. The result means there are dual paths on the relationship between consumer innovativeness and new products adoption behavior. Unlike the early studies, this study shows that there's dual path in relationship between the consumer's innovativeness and new product adoption. That is the consumer who have higher sensory innovativeness perceive the social risk of new products more sensitively than functional risk but the consumer who have cognitive innovativeness perceive functional risk more. So, new product adoption behavior would be different depending on the sensory or cognitive innovativeness.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2009.06a
• /
• pp.187-187
• /
• 2009

Opening of fractures induced by shear dilation or normal deformation can be a significant source of fracture permeability change in fractured rock, which is important for the performance assessment of geological repositories for spent nuclear fuel. As the repository generates heat and later cools the fluid-carrying ability of the rocks becomes a dynamic variable during the lifespan of the repository. Heating causes expansion of the rock close to the repository and, at the same time, contraction close to the surface. During the cooling phase of the repository, the opposite takes place. Heating and cooling together with the, virgin stress can induce shear dilation of fractures and deformation zones and change the flow field around the repository. The objectives of this work are to examine the contribution of thermal stress to the shear slip of fracture in mid- and far-field around a KBS-3 type of repository and to investigate the effect of evolution of stress on the rock mass permeability. In the first part of this study, zones of fracture shear slip were examined by conducting a three-dimensional, thermo-mechanical analysis of a spent fuel repository model in the size of 2 km $\times$ 2 km $\times$ 800 m. Stress evolutions of importance for fracture shear slip are: (1) comparatively high horizontal compressive thermal stress at the repository level, (2) generation of vertical tensile thermal stress right above the repository, (3) horizontal tensile stress near the surface, which can induce tensile failure, and generation of shear stresses at the comers of the repository. In the second part of the study, fracture data from Forsmark, Sweden is used to establish fracture network models (DFN). Stress paths obtained from the thermo-mechanical analysis were used as boundary conditions in DFN-DEM (Discrete Element Method) analysis of six DFN models at the repository level. Increases of permeability up to a factor of four were observed during thermal loading history and shear dilation of fractures was not recovered after cooling of the repository. An understanding of the stress path and potential areas of slip induced shear dilation and related permeability changes during the lifetime of a repository for spent nuclear fuel is of utmost importance for analysing long-term safety. The result of this study will assist in identifying critical areas around a repository where fracture shear slip is likely to develop. The presentation also includes a brief introduction to the ongoing site investigation on two candidate sites for geological repository in Sweden.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.27-27
• /
• 2011

For the design of real applicable molecular devices, current-voltage properties through molecular nanostructures such as metal-molecule-metal junctions (molecular junctions) have been studied extensively. In thiolate monolayers on the gold electrode, the chemical bonding of sulfur to gold and the van der Waals interactions between the alkyl chains of neighboring molecules are important factors in the formation of well-defined monolayers and in the control of the electron transport rate. Charge transport through the molecular junctions depends significantly on the energy levels of molecules relative to the Fermi levels of the contacts and the electronic structure of the molecule. It is important to understand the interfacial electron transport in accordance with the increased film thickness of alkyl chains that are known as an insulating layer, but are required for molecular device fabrication. Thiol-tethered RuII terpyridine complexes were synthesized for a voltage-driven molecular switch and used to understand the switch-on mechanism of the molecular switches of single metal complexes in the solid-state molecular junction in a vacuum. Electrochemical voltammetry and current-voltage (I-V) characteristics are measured to elucidate electron transport processes in the bistable conducting states of single molecular junctions of a molecular switch, Ru(II) terpyridine complexes. (1) On the basis of the Ru-centered electrochemical reaction data, the electron transport rate increases in the mixed self-assembled monolayer (SAM) of Ru(II) terpyridine complexes, indicating strong electronic coupling between the redox center and the substrate, along the molecules. (2) In a low-conducting state before switch-on, I-V characteristics are fitted to a direct tunneling model, and the estimated tunneling decay constant across the Ru(II) terpyridine complex is found to be smaller than that of alkanethiol. (3) The threshold voltages for the switch-on from low- to high-conducting states are identical, corresponding to the electron affinity of the molecules. (4) A high-conducting state after switch-on remains in the reverse voltage sweep, and a linear relationship of the current to the voltage is obtained. These results reveal electron transport paths via the redox centers of the Ru(II) terpyridine complexes, a molecular switch.