• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.6
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• pp.408-415
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• 2016

Small fishing ports and coastal structures installed in a relatively low sea water depth disturb the wave induced current and cause the collapse of equilibrium state of sediment transport. These structures creates diffracted waves and matter the concentration of waves to cause the beach erosion. In order to mitigate these eroding problems on the beach, many counter measurements were proposed such as detached breakwater, groin or headland; however, these methods interrupt the aesthetic view of sandy beach due to the exposed structures above the sea level and have difficulty of applying to those beaches with the good scenery. Furthermore, some of these methods create secondary environmental problems after the installations. To eliminate these problems, one of the countermeasures, artificial reefs have been selected and used worldwide to minimize the disturbance of the scenery and secondary effects on the environment. Meanwhile, it is important to set the design elements for installing the artificial reefs such as that of length, opening width, clearing distances from the shoreline and more. Nevertheless, there are no construction manuals or standards for designing the artificial reefs with these important design elements yet. In this study, different conditions of artificial reefs were used with various cases throughout hydraulic model test to precisely analyze the changes of waves and currents to propose the standards of design elements to install the artificial reefs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3363-3372
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• 2009

Continued jobless growth in economy, coupled with the current economic recession, is aggravating the situation of job market. In order to create more jobs and reduce the economic gap in a society, an independent creative firm of a sole entrepreneurs is suggested as an alternative mean. Understanding entrepreneurial motivations of a sole entrepreneur will be helpful in developing educational programs on starting an independent creative firm and in establishing a relevant government policy. This study, therefore, proposes a new model on entrepreneurial motivations in the independent creative firm and performs case study. The results of the study show that the personal environment and the personal characteristics of entrepreneurs have much effects on motivation of starting the independent creative firms. Among the personal environments, entrepreneurs' educational backgrounds, work experiences, and personal networks have great influences on entrepreneurial motivations. The processes of sustained entrepreneurship involve: (a) the determination of business ideas and goals, (b) the inception of a new business and managerial activities, (c) the entrepreneur's assessment of both intrinsic and extrinsic rewards of business performances, and (d) the adjustment of business ideas and goals in accordance with the results of the assessment. The results of the study could be applied in developing educational programs and consulting guidelines on independent creative firms and in establishing government's supportive policies on the firm.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.717-724
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• 2010

The flash point is one of the most important physical properties used to determine the potential for fire and explosion hazards of flammable liquids. Despite the needs of the experimental flash point data for the design and construction of chemical plants, there is often a significant gap between the demands for the data and their availability. This study have built and compared two models of partial least squares(PLS) and support vector machine(SVM) to predict the experimental flash points of 893 organic compounds out of DIPPR 801. As the independent variables of the models, 65 functional groups were chosen based on the group contribution method that was oriented from the assumption that each fragment of a molecule contributes a certain amount to the value of its physical property, and the logarithm of molecular weight was added. The prediction errors calculated from cross-validation were employed to determine the optimal parameters of two models. And, an optimization technique should be used to get three parameters of SVM model. This work adopted particle swarm optimization that is one of heuristic optimization methods. As the selection of training data can affect the prediction performance, 100 data sets of randomly selected data were generated and tested. The PLS and SVM results of the average absolute errors for the whole data range from 13.86 K to 14.55 K and 7.44 K to 10.26 K, respectively, indicating that the predictive ability of the SVM is much superior than PLS.

• Journal of Pharmaceutical Investigation
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• v.29 no.4
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• pp.295-307
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• 1999

Using a Rheometries Fluids Spectrometer (RFS II), the dynamic viscoelastic properties of aqueous poly(ethylene oxide) (PEO) solutions in small amplitude oscillatory shear flow fields have been measured over a wide range of angular frequencies. The angular frequency dependence of the storage and loss moduli at various molecular weights and concentrations was reported in detail, and the result was interpreted using the concept of a Deborah number De. In addition, the experimentally determined critical angular frequency at which the storage and loss moduli become equivalent was compared with the calculated characteristic time (or its inverse value), and their physical significance in analyzing the dynamic viscoelastic behavior was discussed. Finally, the relationship between steady shear flow and dynamic viscoelstic properties was examined by evaluating the applicability of some proposed models that describe the correlations between steady flow viscosity and dynamic viscosity, dynamic fluidity, and complex viscosity. Main results obtained from this study can be summarized as follows: (1) At lower angular frequencies where De<1, the loss modulus is larger than the storage modulus. However, such a relation between the two moduli is reversed at higher angular frequencies where De>l, indicating that the elastic behavior becomes dominant to the viscous behavior at frequency range higher than a critical angular frequency. (2) A critical angular frequency is decreased as an increase in concentration and/or molecular weight. Both the viscous and elastic properties show a stronger dependence on the molecular weight than on the concentration. (3) A characteristic time is increased with increasing concentration and/or molecular weight. The power-law relationship holds between the inverse value of a characteristic time and a critical angular frequency. (4) Among the previously proposed models, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. The Osaki relation can be regarded to some extent as a suitable model. However, the DeWitt, Pao and HusebyBlyler models are not applicable to describe the correlations between steady shear flow and dynamic viscoelastic properties.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.786-792
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• 2010

This paper presents a real-time lane detection method which can accurately find the lane-mark boundaries in complex road environment. Unlike many existing methods that pay much attention on the post-processing stage to fit lane-mark position among a great deal of outliers, the proposed method aims at removing those outliers as much as possible at feature extraction stage, so that the searching space at post-processing stage can be greatly reduced. To achieve this goal, a grid-based morphology operation is firstly used to generate the regions of interest (ROI) dynamically, in which a directional edge-linking algorithm with directional edge-gap closing is proposed to link edge-pixels into edge-links which lie in the valid directions, these directional edge-links are then grouped into pairs by checking the valid lane-mark width at certain height of the image. Finally, lane-mark colors are checked inside edge-link pairs in the YUV color space, and lane-mark types are estimated employing a Bayesian probability model. Experimental results show that the proposed method is effective in identifying lane-mark edges among heavy clutter edges in complex road environment, and the whole algorithm can achieve an accuracy rate around 92% at an average speed of 10ms/frame at the image size of $320{\times}240$.

• Journal of Environmental Policy
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• v.13 no.3
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• pp.43-73
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• 2014

Cities in Korea have rapidly urbanized and they are not well prepared for natural disasters which have been increased by climate change. In particular, they often struggle with urban flooding. Recently, green infrastructure has been emphasized as a critical strategy for flood mitigation in developed countries due to its capability to infiltrate water into the ground, provide the ability to absorb and store rainfall, and contribute to mitigating floods. However, in Korea, green infrastructure planning only focuses on esthetic functions or accessibility, and does not think how other functions such as flood mitigation, can be effectively realized. Based on this, we address this critical gap by suggesting the new green infrastructure planning framework for improving urban water cycle and maximizing flood mitigation capacity. This framework includes flood vulnerability assessment for identifying flood risk area and deciding suitable locations for green infrastructure. We propose the use of the combination of frequency ratio model and GIS for flood vulnerability assessment. The framework also includes the selection process of green infrastructure practices under local conditions such as geography, flood experience and finance. Finally, we applied this planning framework to the case study area, namely YeonJe-gu an Nam-gu in Busan. We expect this framework will be incorporated into green infrastructure spatial planning to provide effective decision making process regarding location and design of green infrastructure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.241-241
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• 2008

Macrofore formation in silicon and other semiconductors using electrochemical etching processes has been, in the last years, a subject of great attention of both theory and practice. Its first reason of concern is new areas of macropore silicone applications arising from microelectromechanical systems processing (MEMS), membrane techniques, solar cells, sensors, photonic crystals, and new technologies like a silicon-on-nothing (SON) technology. Its formation mechanism with a rich variety of controllable microstructures and their many potential applications have been studied extensively recently. Porous silicon is formed by anodic etching of crystalline silicon in hydrofluoric acid. During the etching process holes are required to enable the dissolution of the silicon anode. For p-type silicon, holes are the majority charge carriers, therefore porous silicon can be formed under the action of a positive bias on the silicon anode. For n-type silicon, holes to dissolve silicon is supplied by illuminating n-type silicon with above-band-gap light which allows sufficient generation of holes. To make a desired three-dimensional nano- or micro-structures, pre-structuring the masked surface in KOH solution to form a periodic array of etch pits before electrochemical etching. Due to enhanced electric field, the holes are efficiently collected at the pore tips for etching. The depletion of holes in the space charge region prevents silicon dissolution at the sidewalls, enabling anisotropic etching for the trenches. This is correct theoretical explanation for n-type Si etching. However, there are a few experimental repors in p-type silicon, while a number of theoretical models have been worked out to explain experimental dependence observed. To perform ordered macrofore formaion for p-type silicon, various kinds of mask patterns to make initial KOH etch pits were used. In order to understand the roles played by the kinds of etching solution in the formation of pillar arrays, we have undertaken a systematic study of the solvent effects in mixtures of HF, N-dimethylformamide (DMF), iso-propanol, and mixtures of HF with water on the macrofore structure formation on monocrystalline p-type silicon with a resistivity varying between 10 ~ 0.01 $\Omega$ cm. The etching solution including the iso-propanol produced a best three dimensional pillar structures. The experimental results are discussed on the base of Lehmann's comprehensive model based on SCR width.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.476-482
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• 2012

In this paper, we analyze and compare several co-channel interference mitigation algorithms for WBAN application in 2.4 GHz ISM frequency bands. ML (Maximum Likelihood), OC (Optimal Combining) and MMSE (Minimum Mean Square Error) has been considered for the possible techniques for interference cancellation in view of the trade off between the performance and the complexity of implementation. Based on the channel model of IEEE 802.15.6 standard, simulation results show that ML and OC attains the lower BER performance than that of MMSE if we assume the perfect channel estimation. But, ML and OC have the additional requirement of implementation for his own and other users's channel estimation process, hence, besides the BER performance, the complexity of implementation and the sensitivity to channel estimation error should be considered since it requires the simple and small sized equipment for WBAN system application. In addition, the gap of detection BER performance between ML, OC and MMSE is much decreased under the imperfect channel estimation if we adopt real channel estimation process, therefore, in order to apply to WBAN system, the trade off between the BER performance and complexity of implemetation should be seriously considered to decide the best co-channel interference cancellation for WBAN system application.

• Management & Information Systems Review
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• v.31 no.3
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• pp.307-321
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• 2012

This paper examines the spillover effect between Korea stock market and Chinese stock market according to increasing economic power of Chinese. Chinese stock market start the transaction one hour and half early than Korea stock market. Especially we focuses the response of Korea stock market after Chinese stock market starts. So we analyze the return an volatility of Korea stock market after 10:30. We employee daily and intraday stock return and volatility. The sample period ranges from January 2008 to April 2010 total 28 months. Our results show that the gap of open price between Korea and Chinese stock market affect the five minute return and volatility of Korea stock market but don't affect the ten minute return and volatility. Recently, this spillover effect has increased more and more. This shows the rapid increase of economic power of Chinese to affect the Korea capital market.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.4
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• pp.191-200
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• 2017

As Korea experienced a Asian foreign exchange crisis in 1997 and a world financial crisis in 2008, the social structure of Korea has undergone many changes. The problem of polarization has become more serious, and the social class has become harder to move between strata. This problem has been accompanied by a growing sense of crisis that the power of social development can be lost along with the problem of population cliffs. Behind the crisis is a reflection of the fact that the growth-oriented economic policies and welfare policies implemented in various European countries can not solve the problem. As an alternative to this, the emergence of social enterprises is attracting attention. Social enterprises have the characteristic of seeking to generate economic profit in order to achieve the purpose of the public interest to provide jobs to the underprivileged. In recent years, the importance of social ventures to expand the scope of new social enterprises in innovative ways has increased. The social venture is a venture business in that it takes risks to develop new areas, not existing business areas, but it also has the character of a social enterprise to achieve the public interest. In other words, an innovative corporate model that provides a creative and challenging solution of social problems in the venture spirit. Although the interest and importance of social enterprises and social ventures are increasing, this academic research is still lacking. The purpose of this study is to introduce and analyze cases of successful social enterprises and social ventures in order to reflect these social interests and their importance and to fill the gap of previous studies. In addition, I hope that this study will stimulate interest and research on the start - up of social venture.