• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.334-336
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• 2005

이동적응망(MANET: Mobile Ad-hoc Network)은 네트워크 하부 구조를 필요로 하지 않은 무선 단말들로 구성된 네트워크이다. 이러한 특성은 네트워크 단절 가능성을 높게 하기 때문에 이동단말들의 데이터 액세스률이 낮아지게 된다는 문제점을 갖는다. 이를 해결하기 위하여 이동 노드들은 데이터의 중복사본을 갖는다. 이동 노드가 갖는 중복사본은 데이터 일관성을 유지하기 위하여 별도의 중복관리 기법이 필요하다. 하지만 MANET을 구성하는 이동 노드들은 일반적으로 제한된 전력을 가지고 있고 단절될 가능성이 높기 때문에 중복 사본의 일관성 보장은 어려운 문제로 지적되고 있다. 기존에 제안된 MANET에서의 데이터 중복관리 기법은 데이터 액세스 빈도수를 계산하여 액세스률을 높이는 방법에 주안점을 두고 있고 갱신 데이터의 일관성 보장은 그 어려움 때문에 주로 판독 연산만 고려하였다. 갱신 트랜잭션을 지원하는 경우 대부분 높은 통신비용을 이유로 데이터 일관성을 보장하지 않는다. 또한 이동 노드가 다수의 서버를 통해서 갱신 연산을 실행하기 때문에 통신 오버헤드로 인하여 전력소모가 크다. 본 논문에서는 주사본 노드를 통하여 갱신을 가능하게 함으로써 데이터 일관성을 유지할 수 있는 데이터 중복 기법을 제안한다. 제안된 기법은 이동 노드들의 에너지 특성을 고려하여 더 않은 에너지를 가진 노드에게 갱신 전파 및 일관성 유지를 의뢰함으로써 상대적으로 낮은 에너지를 갖는 이동 노드의 에너지 효율을 고려하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.51-57
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• 2009

Ubiquitous sensor network is the communication environment where sensor nodes move freely and construct network to get the services from the system. So, it does not need fixed infrastructure and can easily be placed in unaccessible regions like war or calamity area. Wireless sensor network protocol has self-organizing capability, need to adapt topology change flexibly and also has technique that sensor nodes work cooperatively, because network disconnection is frequently occurred due to the active mobility of sensor nodes. In this paper, we design a cluster based fault-tolerant routing protocol for the efficient topology construction and to guarantee stable data transmission in USN. The performance of the proposed protocol is evaluated by an analytic model.

• Journal of Educational Research in Mathematics
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• v.23 no.2
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• pp.237-252
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• 2013

The philosophy of science of Bachelard is introduced mainly with epistemological obstacles in the discussions within mathematics education. In his philosophy, epistemological obstacles are connected with the dialectical developments of science. Science progresses through generalization of concepts and theories by negating things which were recognized as obvious. These processes start with ruptures against the existing knowledge. Epistemological obstacles are failure in keeping distance with the existing knowledge when reorganization is needed. This concept means that there are the inherent difficulties in the processes of concept formation. Finally I compare the view of Bachelard on the developments of science and the 'interiorization-condensation-objectification' scheme of reflexive abstraction in mathematics education and discuss the inherent difficulties in the learning mathematics.

• Membrane Journal
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• v.6 no.2
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• pp.109-116
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• 1996

This work is a fundamental study for applying hybrid process coupling adsorption with microfiltration to waste-water treatment. Phenol was separated by adsorption on powdered activated carbon, adsorbed phenol with activated carbon was separated by microfiltration. As the particle size in suspension increased, filtration resistance decreased, and effect of particle concentration on resistance was less pronounced. The rate of uptake was greatly dependent on the degree of phenol loading. For a smaller amounts of activated carbon, the change of permeate concentration before break point and phenol loading with time were steeper than in the case of large amounts. Permeate concentration before break point decreased with decreasing particle size, this could be due to the increase of outer surface of particle and film mass transfer coefficient.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2002.10a
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• pp.17-30
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• 2002

삼척-도계지역 일대에 분포하는 조선누층군의 풍촌층 석회석은 품위 및 암상에따라 상부고품위대와 하부석회암대로 분대가 가능한데, 이는 삼척-태백간을 북북동으로 흐르는 오십천을 경계로 서쪽에 분포하는 풍촌층과 비교할 때 다소간의 암상차이를 보인다. 즉, 풍촌층의 특징중에 하나인 중부백운암대가 본 역 일대에서는 백운암화가 미약하여 비교적 소폭으로 확인되며, 상부백색대 역시, 발달정도가 미약한 특징을 보인다. 시추탐사결과 확인된 삼척-도계지역의 풍촌층 상부고품위대는 일반적으로 상부백색대$(\pm15m)$ - 백운암대$(\pm5m)$ - 암회색대$(\pm50m)$로 구분되는 것으로 나타났다. 각각의 품위는 상부백색대 : CaO $53_4\~55.6\%$, 백운암대 : MgO $3.0\~18.4\%$, 암회색대 : CaO $50.4\~54.2\%$로 나타나 제철용으로의 사용이 가능하나 백운암대에 대한 선별채광이 부분적으로 요망된다. 이들 석회석은 오십천대단층의 수반단층인 수조의 NNE계열 정단층들에 의해 빈번히 단절되어 있으며 일부지역에서는 EW향의 역단층에 의해 규제되기도 한다. 상기 제단층들은 석회암층을 단절시킬 뿐만 아니라 단층각력, 단층점토, 암맥 등의 불순대를 수반하므로 개발에 장애요소가 되고 있다. 상부고품위대 부존표고는 지역에 따라 다소 차이가 있으나 200ML 내외에서 대부분 확인이 가능하며 지표노출 규모는 작은 편이나 $10^{\circ}$이하의 완경사로 화절층 하부에 부존되어 있어 갱도 채광에 적합한 형태를 이루고 있다.

• The Journal of Korean Association of Computer Education
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• v.7 no.3
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• pp.35-43
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• 2004

Internet-based P2P computing with independent machines suffers from frequent disconnections and security threats caused by leaving, failure, network diversity, or anonymity of participated machines. Replication schemes of shared resources are used for solving these issues in many studies and implementations. We propose an operational replication scheme in P2P computing to share computing resources, and the scheme verifies the correctness of operation against faults and security threats. This verifications are carried out periodically on replicated and dependent working units without global message exchanges over the whole system. The verified working units are treated as checkpoints, and thus they could be put to practical use for fault-tolerance with rollback recovery.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.4
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• pp.527-548
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• 2008

It is said that there exist trouble factors of female-owned businesses and they disturb the growth of female-owned businesses. This paper, focusing on the balancing of work and family roles and discontinuance of career, examines whether trouble factors of female-owned businesses can explain the characteristics of female-owned businesses in Kwangju-Cheonnam region. The results show that these disturbing factors effect the accumulation of capitals for start-ups of femaleowned businesses and careers of female business owners, so that female-owned businesses enter disproportionately on service industry and their sizes are small. These support existing study results.

• Journal of Science and Technology Studies
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• v.8 no.2
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• pp.83-108
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• 2008

A analytical framework is suggested to explain how different standardization each country makes with incorporation of institutional elements such as the state's intervention and inter-firm relations which are considered to have a significant effect on it. Application to mobile telecommunication industry of the framework shows that different innovation system has its own technological standardization. In isolated inter-firm relation system, standardization is achieved through market but in cooperative one, through coordinating activities between participant firms. The state, however, intervenes more deeply in standardization and inter-firm relations are shorter in state-led and isolated firm relation system than in state-led and cooperative firm relation system.

• Journal of Families and Better Life
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• v.28 no.1
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• pp.87-98
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• 2010

The purpose of the present study was to examine the desire of married women to be re-employed and the factors related to this desire. The study gathered information from 240 women who gave up their jobs and careers after marriage. Information included their career history, current psycho-social condition, and family situation. Multiple regression and covariation structure analyses indicated that the desire of married women to go back to paid work was influenced by family economic condition, psycho-social condition, and child care situation. Specifically, the study found that family's monthly income and the age of the last child were negatively related to the women's desire for re-employment. On the other hand, economic pressure and achievement motivation were positively related to the women's desire. Finally, the study found that socio-economic background and external social support were not significantly related to the women’s wish to go back to the workforce.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.649-656
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• 2011

The increase in the traffic demand and behavioral pattern of its use reached the limit for the only means of road construction to bear; thus the multilateral efforts to find a solution to this problem together with the examination and research on this issue, among which the most representative strategy is Ramp Metering System controlling access traffic volume to connection roads. The operation standard and running time was re-established in consideration of geographical conditions and traffic circumstances by considering the standard of operation and running time of the currently operated Jangsu- Jungdong section of the outer ring expressway of Seoul. For this purpose, this research analyzed the operative standard of RMS home and abroad and suggested a new operative standard of ramp metering through the analysis of break points.