• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.34-43
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• 2017

Large amounts of household water are required as common households change from the single-residence types of the past to group-residence types. Therefore, the management of reservoirs is urgently required to ensure the supply of clean household water to users. Important considerations for household water include the duration for which the water is stored in the reservoir, the disinfectant's dilution capacity, and the size of the reservoir to allow for the amount of water required for emergencies and firefighting. The drainage efficiency was analyzed in this study using computational fluid analysis for existing rectangular reservoirs and the newly proposed hexagonal reservoir. Thus, it was determined that the centrifugal force generated at the inlet was maintained until the outlet due to the approximately circular shape of the hexagonal reservoir. The findings of this study verified that the centrifugal force improved the flow rate by approximately 35% compared to existing rectangular reservoirs and that drainage was performed efficiently without stagnation zone.

• Journal of Multimedia Information System
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• v.3 no.3
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• pp.63-68
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• 2016

Environmental downtime produces a significant cost to organizations and makes them unable to do business because what happens in the data center affects everyone. In addition, the amount of electrical energy consumed by data centers increases with the amount of computing power installed. Installation of physical Information Technology and facilities related to environmental concerns, such as monitoring temperature, humidity, power, flood, smoke, air flow, and room entry, is the most proactive way to reduce the unnecessary costs of expensive hardware replacement or unplanned downtime and decrease energy consumed by servers. In this paper, we present remote system for monitoring datacenter implementing using open-source hardware platforms; Arduino, Raspberry Pi, and the Gobetwino. The sensed data displayed through Arduino are transferred using Gobetwino to the nearest host server such as temperature, humidity and distance every time an object hitting another object or a person coming in entrance. The raspberry Pi records the sensed data at the remote location. The objective of collecting temperature and humidity data allows monitoring of the server's health and getting alerts if things start to go wrong. When the temperature hits $50^{\circ}C$, the supervisor at remote headquarters would get a SMS, and then they would take appropriate actions to reduce electrical costs and preserve functionality of servers in data centers.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.444-449
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• 2001

In this paper, a novel ultraviolet sensor is presented based on a photoluminescent porous silicon. Porous silicon layer was formed by chemical etching of surface of pn junction in a $HF(48%)-HNO_3(60%)-H_20$ solution. Incident ultraviolet(UV) light is converted to visible light by photoluminescent porous silicon layer, and then this visible light generates electron-hole pairs in the pn junction, which produces a photocurrent flow through the device. In order to maximize detection efficiency, the peak sensitivity wavelength of the pn junction diode was matched with the peak wavelength of Photoluminescence from porous silicon layer. The porous silicon ultraviolet sensor showed a large output current as UV intensity increases and but very low sensitivity to visible light. The detection sensitivity of porous silicon sensor was calculated as 2.91mA/mW. These results are expected to open up a possibility that the present porous silicon sensor can be used for detecting UV light in a visible background, compared to silicon UV detectors which have an undesirable response to visible light.

• Proceedings of the Technology Innovation Conference
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• 2001.06a
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• pp.117-130
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• 2001

R&D is the core competence of an enterprise. Furthermore, R&D requires huge capital investment and has very risky characteristics. Therefore, to be successful in R&D process, several approaches of engineering economics are used prior to decision-making. Until now, typical approaches of engineering economics such as NPV(net present value) or DCF(Discounted cash flow) have been used. But, they cannot properly capture managerial flexibility to adapt and revise later decisions in response to unexpected market development. In a constantly changing and always uncertain marketplace, managerial operation flexibility and strategic adaptability have become vital in order to successfully capitalize on favorable future investment opportunities and limit losses from adverse market development. For the alternatives of conventional static decision-making approaches, new concept of using real options is introduced. Real option theory is based on financial option's characteristics and checks every revision interval whether situation have changed favorable to decision maker or not. In advantageous situation, the decision maker has only to go on. In contrast, with unfavorable situation, he abandons the investment immediately. In this aspect, real option model is more suitable in very uncertain and dynamic business environment in that it can provide the opportunity to cope with flexibility. This paper suggests efficient and effective R&D investment strategy by using real options model. In addition, this paper compares financial options and real options.

• English Language & Literature Teaching
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• v.16 no.4
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• pp.71-90
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• 2010

This study suggests that English literature educators need to be eclectic and flexible in applying theories and methods, not simply adhering to one or two for all situations and occasions. They need to be available to go with the flow and particularly employ whatever is needed at any given moment of class time. There is a current trend emphasizing English literature as merely a language resource rather than the study of English literature as an end in itself. Without much attention given to literary analysis and criticism, students tend to lack creative and critical thinking abilities. Given the current imbalance, it would seem important to address the issue, and create English class programs that maintain a balance between teaching the study of English literature to improve students' critical thinking abilities, and its use as a language resource. To fulfill this goal, thorough preparation is required. Indeed, we can direct our intelligence more effectively when we are well prepared and we are familiar with the basic methods and mechanics of teaching our subject. The greatest achievement of the English literature class I taught was that the students showed unexpectedly remarkable creative and critical appreciation of the novel we studied, in addition to improving their English language skills.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.349-352
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• 2008

This work is to observe combustion characteristics depending on variation of the solid propellent grain configuration. The LRE (Liquid Rocket Engine) enables adjusting the thrust by controling the required fuel mass glow, but the SRM(Solid Rocket Motor)is not easy to adjust th thrust due to the difficulty of th fuel flow control by its combustion behavior even its configuration is simple. This difficulty can be partly solved by changing th size or the configuration of the propellant grain. In this study a proper grain configuration of a small solid rocket is selected through both the theoretical design and the experimental tests.

• Journal of the Korean housing association
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• v.26 no.6
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• pp.83-92
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• 2015

The purpose of this study is to analyze the characteristics of exterior spaces used by the elderly of housing complex. The exterior spaces are used for going out in everyday life with the view point that the elderly have to go out from the inside home in order to prevent isolating the elderly from local community. For that Toyoshikidai housing complex in Kashiwa city of Chiba prefecture, Japan is selected and carried out questionnaire survey and field survey targeting residents. The results are following as. For spatial characteristics, the location installed benches, location occupied in one part by roof, wall, or plants, place connecting to moving flow of the aged, and an open expanse getting safety from vehicle are taken advantages for the elderly. For using benches, the elderly of 70.1% do not have experience using benches installed in all those places. The the biggest reason is that they are not tired. However, 36.8% of the elderly are using benches in order to take a rest and 20.8% of them are using benches in order to talk with the other people. Bench is ibasho of the elderly.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.41.3-42
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• 2016

No matter how intense magnetic flux it contains, a coronal magnetic structure has little free magnetic energy when a composing magnetic field is close to a potential field, or current-free field where no volume electric current flows. What kind of electric current system is developed is therefore a key to evaluating the activity of a coronal magnetic structure. Since the corona is a highly conductive medium, a coronal electric current tends to survive without being dissipated, so the free magnetic energy provided by a coronal electric current is normally hard to release in the corona. This work aims at clarifying how a coronal electric current system is structurally developed into a system responsible for producing a flare. Toward this end, we perform diffusive MHD simulations for the emergence of a magnetic flux tube with different twist applied to it, and go through the process of structuring a coronal electric current in a twisted flux tube emerging to form a coronal magnetic structure. Interestingly, when a strongly twisted flux tube emerges, there spontaneously forms a structure inside the flux tube, where a coronal electric current changes flow pattern from field-aligned dominant to cross-field dominant. We demonstrate that this structure plays a key role in releasing free magnetic energy via rapid dissipation of a coronal electric current, thereby producing a flare.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.11a
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• pp.197-202
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• 2008

The way we live on our own is distinguished from those of the other countries while the society changes rapidly globalized with the flow. It is called housing culture when culture is discussed in dwelling, what contains living. With the beginning of building Mapo Apartment in 1962, apartment has become the most popular type of housing and currently is provided more than 50% of housing unit in Korea. Even though it has been criticized for a problem of standardization in its form and social issues, its provide increases in its number and its types become hilghly diversified in construction. Therefore the housing culture of apartment should be accepted as a characteristic of our society and it's time to find the identity of our housing culture and make a progress in it. Studies related to apartment are also increased in its number and diversified in its range. The purpose of this study is to go through the trend of studies related to apartment and to analyze subject and content changes according to politic, social and economic changes for the recent 10 years. The study would provide the basic research material related to apartment both to academic area and companies in the future.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.2
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• pp.35-43
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• 2013

The green building is one of biggest factors to go the goal of energy saving and environmental conservation, "reduction of energy consumption, friendly energy technology, recycling of resource, and environmental pollution reduction technology. The purpose of these green buildings realized by the energy-saving technology such as the thermal bridge breaker(or thermal bridge block). Thermal bridges are localized elements that penetrate insulated portions of building envelope that results in heat loss. The purpose of this paper is to describe the technical interactions for patents of a thermal bridge breaker(TTB) used in green building practices, and be subject to investigation to TTB in the leading countries, that is, United State, Europe Union, Japan, and Korea. As a result, there are four TTB categories(roof, wall-slab connection, opening, footing) in house or building. The TTB categories is remarkable technology that is apparatus in slab-wall joints and sealing element of opening frame in walls.