• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.26-32
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• 2015

During the course of a severe accident in a light water nuclear reactor, large amounts of hydrogen can be generated and released into the containment during reactor core degradation. Additional burnable gases [hydrogen ($H_2$) and carbon monoxide (CO)] may be released into the containment in the corium/concrete interaction. This could subsequently raise a combustion hazard. As the Fukushima accidents revealed, hydrogen combustion can cause high pressure spikes that could challenge the reactor buildings and lead to failure of the surrounding buildings. To prevent the gas explosion hazard, most mitigation strategies adopted by European countries are based on the implementation of passive autocatalytic recombiners (PARs). Studies of representative accident sequences indicate that, despite the installation of PARs, it is difficult to prevent at all times and locations, the formation of a combustible mixture that potentially leads to local flame acceleration. Complementary research and development (R&D) projects were recently launched to understand better the phenomena associated with the combustion hazard and to address the issues highlighted after the Fukushima Daiichi events such as explosion hazard in the venting system and the potential flammable mixture migration into spaces beyond the primary containment. The expected results will be used to improve the modeling tools and methodology for hydrogen risk assessment and severe accident management guidelines. The present paper aims to present the methodology adopted by Institut de Radioprotection et de $S{\hat{u}}ret{\acute{e}}$ $Nucl{\acute{e}}aire$ to assess hydrogen risk in nuclear power plants, in particular French nuclear power plants, the open issues, and the ongoing R&D programs related to hydrogen distribution, mitigation, and combustion.

• KIEAE Journal
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• v.3 no.3
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• pp.35-42
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• 2003

It is required impressive expression of urban night environment that makes city as the safe pleasant, convenient place for the economic activity, cultural pleasure and landmarks. This study aims to establish the proper direction to the outdoor lighting in Seoul by analyzing and comparing the lighting situation and policies among Seoul, Shanghai and Yokohama. 1986 Asian Game and 1988 Olympic Game became very important role of activation of outdoor lighting in Korea. Then, outdoor lighting were facilitated in the cultural heritages and bridges along Han river. Millenium Light Plan, Outdoor Lighting Field of Seoul Architectural Award, 2002 Lightscape Local Plan, hosting 2002 World Cup have been good opportunities for the improvement of outdoor lighting in Seoul. In China, outdoor lighting was introduced to the city of Shanghai according to the orders of the president in 1988. Outdoor lighting of Shanghai have created unique lighting with beautiful color and intensive brightness under the direction of city government. Outdoor lighting of Shanghai needs the standard of lighting design and improvement of lighting facilities. Outdoor lighting was introduced to Japan with 1964 Tokyo Olympic games. Urban outdoor lighting plan was carried out in Yokohama in 1986. In Yokohama, outdoor lighting of civilian and public facilities have been harmonized. And the city government of Yokohama established the committee of promotion of outdoor lighting in its government to support and manage the outdoor lighting with corporation of civilian organization. As the result of comparative analysis on Seoul, Shanghai, Yokohama, Seoul Metropolitan Government needs the criteria and incentive system of outdoor lighting.

• Smart Structures and Systems
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• v.17 no.6
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• pp.957-980
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• 2016

Structural damage detection (SDD) is a challenging task in the field of structural health monitoring (SHM). As an exploring attempt to the SDD problem, a hybrid self-adaptive Firefly-Nelder-Mead (SA-FNM) algorithm is proposed for the SDD problem in this study. First of all, the basic principle of firefly algorithm (FA) is introduced. The Nelder-Mead (NM) algorithm is incorporated into FA for improving the local searching ability. A new strategy for exchanging the information in the firefly group is introduced into the SA-FNM for reducing the computation cost. A random walk strategy for the best firefly and a self-adaptive control strategy of three key parameters, such as light absorption, randomization parameter and critical distance, are proposed for preferably balancing the exploitation and exploration ability of the SA-FNM. The computing performance of the SA-FNM is evaluated and compared with the basic FA by three benchmark functions. Secondly, the SDD problem is mathematically converted into a constrained optimization problem, which is then hopefully solved by the SA-FNM algorithm. A multi-step method is proposed for finding the minimum fitness with a big probability. In order to assess the accuracy and the feasibility of the proposed method, a two-storey rigid frame structure without considering the finite element model (FEM) error and a steel beam with considering the model error are taken examples for numerical simulations. Finally, a series of experimental studies on damage detection of a steel beam with four damage patterns are performed in laboratory. The illustrated results show that the proposed method can accurately identify the structural damage. Some valuable conclusions are made and related issues are discussed as well.

• Wind and Structures
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• v.10 no.3
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• pp.287-300
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• 2007

Wind action is a factor of fundamental importance in the structural design of light or slender constructions. Codes for structural design usually assume that the incident mean wind velocity is parallel to the ground, which constitutes a valid simplification for frequent winds caused by meteorological phenomena such as Extratropical Storms (EPS) or Tropical Storms. Wind effects due to other phenomena, such as thunderstorms, and its combination with EPS winds in so-called squall lines, are simply neglected. In this paper a model that describes the three-dimensional wind velocity field originated from a downburst in a thunderstorm (TS) is proposed. The model is based on a semi empirical representation of an axially-symmetrical flow line pattern that describes a stationary field, modulated by a function that accounts for the evolution of the wind velocity with time. The model allows the generation of a spatially and temporally variable velocity field, which also includes a fluctuating component of the velocity. All parameters employed in the model are related to meteorological variables, which are susceptible of statistical assessment. A background wind is also considered, in order to account for the translational velocity of the thunderstorm, normally due to local wind conditions. When the translation of the TS is caused by an EPS, a squall line is produced, causing the highest wind velocities associated with TS events. The resulting vertical velocity profiles were also studied and compared with existing models, such as the profiles proposed by Vicroy, et al. (1992) and Wood and Kwok (1998). The present model predicts horizontal velocity profiles that depend on the distance to the storm center, effect not considered by previous models, although the various proposals are globally compatible. The model can be applied in any region of interest, once the relevant meteorological variables are known, to simulate the excitation due to TS winds in the design of transmission lines, long-span crossings, cable-stayed bridges, towers or similar structures.

• Journal of Agricultural Extension & Community Development
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• v.3 no.1
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• pp.67-81
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• 1996

Our agricultural extension system with all its success and failures, rewards and punishment was introduced 50 years ago with particular reference from United States. Some of the established principles and policies of effective extension work were shaken off for immediate result. But the results were not praiseworthy. The purpose of this study is to throw some light on the question of systems and approaches on agricultural extension that can adequately meet the challenges of the future. Our extension system is `special government type` which administers a nation-wide network of extension and training services in close collaboration with that of the experiment station. This type, however, has innate weakness which inclined to be standardized, inflexible, and irrelevant to actual needs of farming communities and problems of farmers. In this regard, it is necessary to consider another approaches of agricultural extension: `Government Type`, `Agricultural University`, `Farmers Organization`. The characteristics features, advantages and disadvantages of these models have been discussed. Each model has been found wanting in one way or another to meet the needs and interest of the present Korean situation. In view of the agricultural situation, and considering the expected changes of farmers and technologies in the years ahead, the `modification (especially to the direction of provincial government) of preset system` was expected which would be operationally flexible and organizationally unified and decentralized. The modification of present system should include the following characteristics: 1) universal contact with client system, 2) local planning based on the needs of clients, 3) using multiple method of nonformal education, 4) fitting with both general and specialized farming systems, 5) accommodating variable clients, technologies and educational objects.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.219-227
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• 2013

The purpose of this study was to quickly and effectively identify the Nosema disease of bumblebees in Gangwon Province in Korea. Bumblebees are crucial pollinators of various crops, and microsporidia are the critical pathogens of these hosts. When bumblebees are infected with Nosema bombi, their abdomens can become distended. Paralyzed and infected workers often become sluggish and die early. We have identified the morphology of the microsporidium by light and electron microscopy, and found it to have fairly small oval spores, as has been described previously in many other articles. For the specific and sensitive diagnosis of the microsporidian parasite N. bombi in bumblebees, we have developed an improved method of the polymerase chain reaction (PCR) for expeditious diagnosis. Two pairs of primers were tested on N. bombi and the related microsporidia Nosema apis and Nosema sp., both of which infect Bombus ignitus and Bombus hypocrita sapporoensis. Furthermore, we have verified and analyzed the 16SrRNA sequence data of N. bombi in bumblebees by using the Basic Local Alignment Search Tool (BLAST) server at the National Center for Biotechnology Information.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.12a
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• pp.7-8
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• 2011

Although yttrium iron garnet (YIG) has provided a great vehicle for the study of spin waves in the past, associated difficulties in film deposition and device fabrication using YIG had limited the applicability of spin waves to practical devices. However, microfabrication techniques have made it possible to characterize both the resonant as well as the travelling characteristics of spin waves in permalloy (Py). A variety of methods have been used for measuring spin waves, including Brillouin light scattering (BLS), magneto-optic Kerr effect (MOKE), vector network analyzer ferromagnetic resonance (VNA-FMR), and pulse inductive microwave magnetometry (PIMM). PIMM is one of the most preferred methodologies of measuring travelling spin waves. In this method, an electrical impulse is applied at one of two coplanar waveguides patterned on top of oxide-insulated Py, producing a local disturbance in the magnetization of the Py. The resulting disturbance travels down the Py in the form of waves, and is inductively picked up by the other coplanar waveguide. We investigate the effect of the pulse width of excitation pulses on the generated spin wave packets using both experimental results and micromagnetic simulations. We show that spin wave packets generated from electrical pulses are a superposition of two separate spin wave packets, one generated from the rising edge and the other from the falling edge, which interfere either constructively or destructively with one another, depending upon the magnitude and direction of the field bias conditions. A method of spin wave amplitude modulation is also presented by the linear superposition of spin waves. We use interfering spin waves resulting from two closely spaced voltage impulses for the modulation of the magnitude of the resultant spin wave packets.

• Korean Journal of Medicinal Crop Science
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• v.1 no.2
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• pp.162-165
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• 1993

To determine optimal sowing date of Job's Tears in southern-Region of Korea,Job's Tears cv. Local cultivars Ewon and Heuksuk were grown under the three different sowing dates. As sowing date was delayed, the heading and maturing date were delayed also and yield components such as plant height, stem diameter, number of stems, weight of 100grains and that of 1 l, etc. were the highest at the sowing date of Apr. 15. Yield of stem and seed were the heaviest in Apr. 15 seeding and they were light in the early or late sowing, Judging from the results reported above, optimum seeding date of Job's Tears seemed to be Apr. 15.

• KIEAE Journal
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• v.12 no.3
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• pp.3-10
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• 2012

The purpose of this study is to seek a planning approach for children's museum within Korean context that promotes community participation. A literature review method and a field survey method were used. Literature reviews on community participation paradigm, residents' participation and donation networks in community regeneration processes, and finally on case studies on children's museum in Korea were carried out. Through the field survey on Chicago Children's Museum(CCM) located in downtown Chicago, its role was identified as networking systems of community participation and donation and was verified as a socio-physical base for vitalizing donation culture that is an active and a leading community participation method. As a result, CCM has engaged many partnerships with city organizations and local schools to provide diverse and unique programs that are not only targeted to children but also parents, teachers and visitors. Also, an evolution of CCM through various types of donations and community participation was delineated. CCM was found successfully in restoring community spirit and vitalizing economical growth where it once was a decayed city area. Rather than focusing on descriptive technique of typical children's museum, this study explored how community fabric is made and acted out, through rethinking community participation's value, and how it can influence a physical space. CCM, as a good example of community participatory museum, the results can be used as a reference in planning and directing community participation based children's museums in Korea. It is significant to shed light on children's museum as an opportunity of social space which can empower community.

• Archives of design research
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• v.15 no.3
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• pp.83-92
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• 2002

In the 21st century, as localization is reinterpreted as an important part of globalism and as local culture is recognized as a device to increase the competitive power, every city is trying to develop its identity and improve its image while coping with change of the international and domestic environment. Therefore, basic research was preformed to establish the city image identity of Gwangju and as a result, an ideological slogan " City of Light and Life, Gwangju" and basic factors were developed. This study aims to analyze the condition of the city, focusing on design factors that the city image is comprised of, and establishes a long-term strategy for urban environment development by considering the developmental potential of the city. and focuses on case studies for establishment of an image suitable for Gwangju. Case studies focusing on the urban environmental development were presented and the results were applied to Gwangju. From the results, further studies can be pursued according to a long-term strategy. strategy.