• Journal of IKEEE
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• v.26 no.3
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• pp.483-487
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• 2022

In this paper, we design a self-powered Arduino system for solar energy harvesting and explain its operation. To perform the operation, the Arduino system senses the amount of solar energy that changes every moment and adjusts the ratio of the active mode and sleep mode operation time according to a given solar light intensity. If the intensity of sunlight is strong enough, the Arduino system can be continuously driven in active mode and receive sufficient power from sunlight. If not, the system can run in sleep mode to minimize power consumption. As a result, it can be seen that energy consumption can be minimized by reducing power consumption by up to 81.7% when using sleep mode compared to continuously driving active mode. Also, when the light intensity is at an intermediate level, the ratio between the active mode and the sleep mode is appropriately adjusted according to the light intensity to operate. The method of self-control of the operating time ratio of active mode and sleep mode, proposed in this paper, is thought to be helpful in energy-efficient operation of the self-powered systems for wearables and bio-health applications.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.2
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• pp.53-67
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• 2008

In this study, seismic control performance of friction dampers installed in a reinforced concrete shear wall-moment frame system, of which main lateral force resisting system is a shear wall, is investigated. Three configurations of friction dampers are investigated. One is a diagonal brace type reinforcing the shear wall directly, another is a diagonal brace type reinforcing the moment frame without the shear wall, and the other one is a vertical boundary element type installed at both ends of the shear wall. In addition, various levels of the total friction force and its distribution methods are examined. Time history analysis considering material nonlinearity is conducted for seismic loads increased by the enhanced design code compared to the initial design loads, and energy dissipation, lateral loads and structural member damages are analyzed. As a result, the shear wall-reinforcing diagonal brace type with the total friction force of 30 % of the reference friction force gives the best performance on the whole, and the distribution methods of the friction force do not have remarkable difference in effects. Also, concentrated installation in adjacent four stories shows just a little compromised control performance compared to the entire story installation.

• The Journal of Sustainable Design and Educational Environment Research
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• v.16 no.2
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• pp.44-53
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• 2017

Facility management is to maintain and develop the primary structural, functional, aesthetic performance of facility in order to guaranty the users' daily convenience and safety. However it is hard to maintain and serve their intended function and safe environment from the beginning as times go by. As present educational government of city and local area has been performing formally facility check and management as well as maintenance of school facility, it is hard to respond a dangerous situation at the suitable time and safety prevention plans are delayed. In addition, educational environment improving budget have been unreasonably decided not according to the allocating criteria. Therefore, this research developed a same, simple, and quantitative evaluation method of deterioration level of elementary, middle, and high School in Korea and verified usability of the method through the case study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.743-754
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• 2014

Recently, Information-Centric Networking(ICN), different from traditional IP-based networking, has been highlighted. Content-Centric Networking(CCN), proposed by Van Jacobson, is a representative scheme of the ICN architectures. It can deliver messages slightly faster than the IP-based networking by focusing on the access and delivery to the content itself. However, CCN is restricted to distribute the information without transmitting the request packet in advance because it is pull-based architecture by content requester. In addition, it has a problem that the Pending Interest Table(PIT) could be overloaded easily when DDoS attack happens. In this paper, we suggest an algorithm using a push-based scheme without request packets and overcoming PIT overload situation by Interest Group Push Table(IGPT). The proposed scheme enables to transmit a large amount of content than an existing scheme during the same amount of time in terms of timely-delivery and security.

• Culinary science and hospitality research
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• v.3
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• pp.23-40
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• 1997

This study has been made on the basis of the theoretical model of Beeker's time allocation concerning housewives' advance into society-- a primary cause for enlargint the scope of our food service market and developing the food service industry as a whole. The primary purpose of this study is to clarify the close relationship between housewives' activities in the course of allocating their time and the demand for the food service through Beeker's theory of“Total income and Total price”, analyzing the information obtained through the questionaires sent to the housewives in metropolitan areas. The result of the questionaires shows that the demand of food service is closely related to women's market activities. Yet it has become clear that the demand for food service correlates with housewives' allocation of time in terms of sharing profits. As a result, it is true that the increase in housewives' income per hour has brought about the increase of the term of employment and the decrease in their cooking time, thus greatly increasing the opportunities to dine out. In order words, the increase of housewives' income and the decrease in their cooking time have come to make a great contribution to shortening the time needed to take care of family matters while increasing the demand for eating out, or food service. And it is also clear that the common practice to dine out is derived from the reduction in our domestic duties, indicating the choice of social division of labour, but is needs to be noted that the gradual increase in women's income is sure to have exerted a considerable influence on this practice of eating out.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.575-582
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• 2008

다목적댐의 레크레이션 편익은 수자원 관리 측면에서 매우 중요한 요소이다. 그러나, 레크레이션 편익의 중요성에도 불구하고 이에 대한 충분한 고려없이 댐의 관리와 다목적댐에 대한 평가가 이루어진 결과 경쟁적인 물의 용도간 부적정한 유량배분의 결과를 초래하고 있었다. 최근 비록 시범적이지만 하천의 환경개선을 위해 다목적댐의 flusing 방류가 이루어지고 잇는 점도 댐의 기능이 점차 확장되어 가고 있음을 보여주고 있다. 다목적댐의 레크레이션 편익에 대한 인식은 효율적인 수자원 관리뿐만 아니라 레크레이션 이외의 다목적댐의 다른 용도의 진실된 가치 및 효율성을 확보하기 위해 어떻게 효율적으로 시간의 흐름에 따라 다목적댐의 저수(貯水)가 방류되어야 하는지에 대한 이해로 연결된다. 다목적댐의 레크레이션 편익 측정은 댐의 역할에 대한 진정한 평가가 될 수 있으며 그동안 간과되어 왔던 댐 건설로 인해 가능하게 된 레크레이션 기회를 가치화하는 시도가 될 수 있다. 본 연구는 조건부가치측정법(Contingent Valuation Method, CVM)을 이용하여 서울과 춘천지역을 대상으로 표본에 대한 설문조사와 함께 집중그룹인터뷰(Focus Group Interview, FGI)를 통해 소양강댐의 레크레이션 편익을 측정하였다. 서울은 소양강댐의 하류지역에 위치하면서 일반적으로 소양강댐의 건설로 인해 가장 큰 혜택을 누리는 지역이며 춘천지역은 소양강댐의 주변지역으로 소양강댐의 건설로 인해 가장 많은 피해를 입는 지역으로 여겨지고 있어 양 지역에서 느끼는 소양강댐에 대한 인식은 매우 독특할 것이라는 기대와 함께 댐으로 인한 레크레이션은 댐 저수지뿐만 아니라 댐 하류 하천 전체에 걸쳐 이루어지기 때문에 댐 저수지 지역인 춘천과 댐 하류지역인 서울을 대상지역으로 삼았다. 4개의 시나리오를 적용한 결과 소양강댐의 연간 레크레이션 편익은 235억원$\sim$913억원으로 추정되어 소양강댐의 주요 기능인 용수공급이나 발전에 따른 편익과 비교할 때도 결코 작지 않은 편익을 보여주고 있다. 아울러, 일반적으로 댐 건설로 인한 피해자로 인식되고 있는 하천의 상류지역인 댐 주변지역에 거주하는 사람들의 지불의사액(Willingness to Pay, WTP)이 댐의 수혜자로 인식되는 하류지역에 거주하는 사람들의 WTP보다 크다는 것과 댐 주변지역에 거주하는 사람들은 댐에 대하여 양 극단적인 태도, 즉 강한 애착과 강한 반감을 함께 보이는 것으로 나타났다. 본 연구는 레크레이션 기능이 댐의 주요 기능으로 고려되어야 하는 가에 대한 해답을 줄 수 있는데, 그동안 댐의 레크레이션 편익 측정을 어렵게 하였던 댐의 레크레이션 편익의 개념화를 통해 편익이 측정 가능하며 소양강댐의 경우 다른 목적의 물 사용 용도보다 편익이 클 수 있기 때문에 향후 다목적댐의 주요 기능을 확장할 필요성을 보여준다. 또한, 레크레이션 편익을 어떻게 내재화(內在化)하여야 하는지에 대한 향후 연구의 필요성도 제기한다.

• Journal of Korean Society of Forest Science
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• v.80 no.4
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• pp.427-435
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• 1991

Linear programming(LP) is a well-known method in optimizing timber harvest schedules. This paper describes a linear programming formulation of korean pine stands for timber harvest scheduling problems. Simulation technique and LP were applied to optimize the time and space distribution of the sustained yield for the 10-year forest management planning horizon. Growthfunction of korean pine stands in study area was derived with the yield table. This growthfunction was contained to the simulation model in estimating of changing stand volume conditions for the planning horizon. These estimated values were served as the basic data of LP model, and LP model was formulated with the maximum of periodical harvest volume calculated by the classical yield regulation method (Paulsen-Hundeshagen formula) and the maximum of periodical harvest area calculated for the normal age distribution. The timber harvest schedule was established periodically for each subcompartment of korean pine stands in experiment forest of College of Forestry in Kangweon National University with the here developed LP model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2191-2204
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• 1997

An efficient packet transmit scheduling algorithm should be able to allocate the resource to each connection fairly based on the bandwidth and quality of service requirements negotiated during the call admission procedure and it should be able to isolate the effects of users that are behaving badly. In this paper, we propose an effective round-robin packet transmit scheduling mechanism, which we call the delay tolerant packet reserving scheme (DTPRS) based on delay QoS requirments. The proposed scheme can not only provide fairness and but also reduce delay, delay variation, and packet loss rate by reserving output link time slots of delay tolerant packets and assigning the reserved slotsto delay urgent packets. Our scheme is applicable to high speed networks including ATM network because it only requires O(1) work to process a packet, and is simple enough to implement.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.385-392
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• 2012

The definition of the product market in a supplier's point of view can cause various problems in the market activities of companies because specific situations are excluded and the consideration for discontinuity is lacking by identifying segmented markets with processes, raw materials, the similarity of product functions and so forth. Furthermore, as this definition is static and general, it is difficult to express and predict the dynamic market changes. Meanwhile, customer-oriented market segment can be obtained by grouping substitutable products and related customers in the situation pursuing specific benefits. This definition of the product market enables us to find threats and opportunities emerging in markets and promotes effective performance assessments and resource allocation. The purpose of this paper is suggesting a framework to select data mining techniques proper for the customer data characteristics to identify customer oriented product market.

• The Mathematical Education
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• v.48 no.2
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• pp.191-206
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• 2009

In this study, we investigate the effects of the methods of time allocation in lecturing on the mathematical academic achievement of freshmen in institute of technologies. The subjects are 392 freshmen from three universities participated in ABEEK(Accreditation Board for Engineering Education of Korea). They belong to three groups in accordance with the methods of time allocation in lecturing; 75 minutes twice a week(79 students) and 150 minutes continuously once a week(77 students) (university 1 of 156 students), 100 minutes twice a week(56 students) and 200 minutes continuously once a week(60 students) (university 2 of 116 students) and 50 minutes and 100 minutes separately once a week(62 students) and 150 minutes continuously once a week(58 students) (university 3 of 120 students). The results of this paper are summarized as follows: Firstly, the achievement of separate time-allocation groups is higher than that of continuous time-allocation groups. Secondly, the achievement of middle class students and low class students has higher effects when they are taught by using the methods of separate time-allocation in lecturing. Finally, the achievement of groups using 75 minutes twice a week is higher than that of using 50 minutes and 100 minutes separately once a week. In conclusion, this study suggests that the method of separate time allocation in lecturing using 75 minutes twice a week could be an advisable means to help those who achieve middle and low scores in the first college mathematics.