• Journal of the Korean GEO-environmental Society
• /
• v.11 no.12
• /
• pp.57-62
• /
• 2010

In this study, the effect of different silt contents on the shear characteristics of silty sands was evaluated. Two series of triaxial compression tests were performed on the cylindrical specimens of compacted Nakdong river sand with 10% and 30% silt contents under unconsolidated undrained condition. All identical specimens were prepared to compact with same initial water content for five layers and saturated using control panel and then sheared under initial effective confining pressure, 100 to 400kPa. All specimens exhibited a strain softening tendency after failure in stress-strain curves and deviator stresses of specimens with 10% silt content were greater than those of specimens with 30% silt content. Pore water pressures of specimens with 10% silt content were observed negative(i.e. swelling) due to increasing void ratio after failure but those of specimens with 30% silt content were shown only positive. The behavior of compacted cylindrical specimens with low silt content was more dilative than that of high silt content. Peak deviator stresses decreased as increasing silt content and peak pore water pressures increased as increasing silt content.

• Communications of Mathematical Education
• /
• v.11
• /
• pp.259-277
• /
• 2001

본 연구는 개방형 문제를 활용한 평가가 수학적 창의력에 미치는 효과를 분석함으로써 수학적 창의력을 신장시킬 수 있는 평가 방법을 찾는데 그 목적이 있다. 이를 위해 대구광역시 소재의 C중학교 2학년 1개반과 S중학교 2학년 1개반을 임의로 선정하여 한 반은 개방형 문제를 활용한 평가 집단으로 하고 다른 한 반은 전통적 평가 집단으로 무선 할당하여 실험연구를 실시하였다. 실험처치는 두 집단에게 서로 다른 유형의 평가를 실시하는 것으로, 실험집단은 개방형 문제를 평가과제로 하여 실험집단 담임 교사가 평가를 실시하였으며, 비교집단은 객관식 및 주관식 단답형 문제를 평가과제로 하여 비교집단 담임교사가 전통적인 평가를 실시하였다. 본 연구에서 사용한 검사도구는 수학적 창의력 검사로 사전 사후검사 모두 같은 검사지를 사용하였다. 사후 수학적 창의력 검사의 평균의 차를 t-검정한 결과 유의도p=.025(p < .05)로 실험집단과 비교집단 사이에는 통계적으로 유의미한 차가 있는 것으로 나타났다. 수학적 창의력의 각 요소별로 차이가 있는지 알아보기 위해 사후 창의력 검사의 각 요소별로 평균의 차를 t-검정한 결과, 유창성과 융통성은 각각 유의도 p=.030, p=.040으로 p < .05 수준에서 통계적으로 유의미한 차이가 있었으며, 독창성은 유의도 p=.052로 p < .1 수준에서 통계적으로 유의미한 차이를 보였다. 연구결과 개방형 문제를 활용한 평가가 전통적 평가보다 수학적 창의력 향상에 더 효과적이며, 수학적 창의력의 세 가지 요소(유창성, 융통성, 독창성)의 향상에도 효과적인 것으로 나타났다. 결론적으로 개방형 문제를 활용한 평가가 수학적 창의력 신장에 효과적인 방법임을 시사한다.질공학적 특성의 위도별, 깊이별 변화는 탄산질 퇴적물과 규질 퇴적물의 분포, 수층의 생산성 및 수심변화에 따른 용해도와 퇴적을 차이 그리고 침식 및 재퇴적작용 등 퇴적 과정이 위도별로 달랐기 때문으로 판단된다.haetoceros resting spores/Chaetoceroe vegetative cells도 80 cm 보다 상층에서는 높게 나타나 규조온도지수 분포와도 일치하는 경향을 보인다. 이상의 규조군집 분석 결과에 의하면, 홀로세의 후빙기동안 본 연구 지역인 동해 북동부에는 대마 난류의 유입이후 현재와 유사한 환경이 우세하게 발달했으나, 난류종 P. doliolus의 변화는 동해내에서 대마난류의 세기가 반복되었음을 지시하고 있다./3 수준으로 높다. 결론적으로 풍부한 화학물질들을 함유한 제주해류는 남해 및 동해의 생지화학적 과정들에 있어 상당히 중요함을 시사한다.다. 수조 상층수 중 Cu, Cd, As 농도는 모든 FW, SW수조에서 시간이 지남에 따라 일관성 있게 감소하였고, 제거속도는 Cu가 다른 원소에 비해 빨랐다. 제거속도는 FW 3개 수조 중 FW5&6에서 세 원소 모두 가장 느렸고, SW 3개 수조 중에서는 SW1&2에서 가장 빨랐다. SW와 FW간 제거속도 차이는 세 원소 모두 명확치 않았다 Cr은 FW에서 전반적으로 감소하는 경향을 보였지만 SW에서는 실험 초기에 감소하다 24시간 이후에는 증가 후 일정한 양상을 보였다. Pb은 FW에서 전반적으로 감소했지만 SW에서는 초기에 급격히 증가 후 다시 급격히 감소하는 양상을 보였다 Pb 또한 Cu, Cd, As와 마찬가지로 SW1&2에서 제거속도가 가장 빠르게 나타났다. FW 상층수 중 Hg는 시간에 따라 급격히 감소했고,

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.8
• /
• pp.528-533
• /
• 2014

Recently, people interest in environmental pollution and attempt to improve the indoor air quality contaminated with various pollutants since it is very important to construct healthy and comfortable living environment. In the current study, we used the technology that has first received the certification of green technology for improving the removal efficiency of malodor causing substances. This green technology is a new technology to increase the reactivity of the odorous substances with OH radicals for oxidation reaction by using an infrared lamp in the existing air purification system. Comparing the efficiency of the green technology with the infrared lamp to that of the existing technology of air cleaner, there was a difference in the decomposition efficiency depending on the initial concentrations and speciation of the odorous substances. The removal efficiencies of contaminants were enhanced by 16.9 and 13.2% at low and high concentrations, respectively.

• The KIPS Transactions:PartC
• /
• v.14C no.3 s.113
• /
• pp.239-254
• /
• 2007

Ubiquitous computing supports environment to freely connect to network without restrictions of place and time. This environment enables easy access and sharing of information, but because of easy unauthorized accesses, specified security policy is needed. Especially, ubiquitous sensor network devices use limited power and are small in size, so, many restrictions on policies are bound to happen. This paper proposes double-key based light weight security protocol, independent to specific sensor OS, platform and routing protocol in ubiquitous sensor network. The proposed protocol supports safe symmetric key distribution, and allows security manager to change and manage security levels and keys. This had a strong merit by which small process can make large security measures. In the performance evaluation, the proposed light weight security protocol using double-key in ubiquitous sensor network allows relatively efficient low power security policy. It will be efficient to ubiquitous sensor network, such as smart of ace and smart home.

• Journal of the Economic Geographical Society of Korea
• /
• v.9 no.3
• /
• pp.441-458
• /
• 2006

Culture is an indispensable element in modern society in improving the quality of life for city dwellers and stimulating the urbanization. The conspicuous emergence of cultural cities, which is a new paradigm, can be understood in that context. Global cities are pursuing cultural cities, and autonomous regions in Korea are also pushing ahead with the urbanization which combines cultural elements. Specifically, Nam-gu of Incheon has set an example of successful cultural city for other autonomous regions. The cultural environmental policy of Nam-gu is deemed to have retained the infrastructure, cultural urban landscape and living space, and a plenty of contents. The real significance of cultural city lies in the pursuit of sustainable urban development as a culture-friendly city. For that, the direction of cultural environmental city has to be firmly set, and related law and system should be strengthened. Above all, it is critical to pursue human-oriented cultural city by showing citizens what roles they have to play, setting the right direction, and improving the partnership.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.9-9
• /
• 2020

하천공간은 홍수방어와 용수사용을 위한 수자원관리 측면의 공간에서 벗어나 국민들의 삶의 질 제고와 이용편익, 생활환경의 중심 공간으로 자리매김하고 있다. 국민의 하천에 대한 눈높이가 상승하고 있음에도 하천공간이 주는 여러 가치에 대해서는 학술적 검토가 미진하였으며, 그에 따라 정책에도 제한적으로 반영되고 있다. 본 연구에서는 설문조사, 요인분석 등을 통해 주민 입장에서 부여할 수 있는 하천의 다면적 가치를 식별하고 주민친화적 관리를 위한 성과지표를 개발하고자 하였다. 특히 본 연구가 개발하고자 하는 성과지표 체계는 기존 방식대로 객관화·정량화가 불가능한 주민의 정성적·주관적 만족도를 측정할 수 있는 지표를 개발하는 것에 목적이 있다. 먼저, 관련된 각종 선행연구 및 도로 등 타분야 사례, 일본 등 해외 사례 등을 종합하여 하천의 4가지 사업부문인 치수, 이수, 환경, 친수를 모두 포괄하는 지표체계안을 구축하였다. 다만 본 연구가 주민친화적 하천관리를 목적으로 하므로 상대적으로 환경·친수 부문 지표의 비중이 높았으며, 총 지표 개수는 25개로 도출하였다. 도출한 지표체계안을 바탕으로 주민 대상 설문조사를 실시하였으며, 요인분석법을 활용하여 지표체계를 재정리하였다. 요인분석법은 학술적·실무적으로 가장 널리 사용되는 PCA 추출법과 Varimax 회전법을 채택하였으며, KMO 및 Barlett's 검정법을 활용하여 자료 검정을 수행하였다. 그 결과, 하천 부문 주민만족 요인은 3가지로 나타났으며, 이를 각각 '최소친수기반요인', '안전·청결기반요인', '친수활동지원요인'으로 정의하였다. 요인 분석 결과를 바탕으로, 3개 영역, 6개 세부 영역, 24개 평가항목으로 구성된 성과지표 체계를 도출하였다. 마련된 성과지표의 항목별 중요도를 전국 대상 설문조사를 통해 분석한 결과, 영역 중에서는 '안전·청결기반요인'이 가장 중요한 것으로 나타났으며, 특징적으로는 CCTV, 장애·위험물 제거, 수질·공간청결성, 공공화장실 만족성 등이 중요한 것으로 나타났다. 또한 대전지역 국가하천과 지방하천을 사례지역으로 성과지표를 비교한 결과, 국가하천의 성과가 대체로 높게 나타났으며 '최소친수기반요인' 영역의 성과가 상대적으로 높은 것으로 나타났다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.1
• /
• pp.102-113
• /
• 2013

The purpose of this study was to examine parental perceptions on the importance, performance level, and satisfaction with foodservice quality at daycare centers in the Compensation and Welfare Service institute. The questionnaire was developed to measure thirty-two attributes of foodservice operations are administered to 598 parents and 23 foodservice supervisors from June 22, 2009 to July 10, 2009. The parents placed a high importance on the need for foodservices, earning 4.70 points out of 5 points. Their perceptions of foodservice quality menu, foodservice ingredients and effects, facilities, sanitation, and service scored even higher than performance. The overall satisfaction level for foodservice compared to performance was 4.33 and 4.03 points out of 5 points, respectively. Multiple regression analysis indicated that 98.6% of the variance in parents' overall satisfaction scores was explained by six dimensions.

• Journal of Internet Computing and Services
• /
• v.6 no.4
• /
• pp.59-73
• /
• 2005

Caching query results and reusing them in processing of subsequent queries is an important query optimization technique. Materialized view and view indexing are the representative examples of such a technique. The two schemes had received much attention for relational databases, and have been investigated for XML data since XML emerged as the standard for data exchange on the Web. In XML view indexing, XML view xv which is the result of an XML query is represented as an XML view index(XVI), a structure containing the identifiers of xv's underlying XML elements as well as the information on xv. Since XVI for xv stores just the identifiers of the XML elements not the elements themselves, when xv is requested, its XVI should be materialized against xv's underlying XML documents. In this paper, we address the problem of integrating an XML view index management system with an RDBMS based XML storage system. The proposed system was implemented in Java on Windows 2000 Server with each of two different commercial RDBMSs, and used in evaluating performance improvement through XML view indexing as well as its overheads. The experimental results revealed that XML view indexing was very effective with an RDBMS based XML storage system while its overhead was negligible.

• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.175-184
• /
• 2012

This study was conducted to develop new mattress systems with vegetation base materials for protecting stream bank and rapid rehabilitation. Vegetation base materials are primarily compounded with fine soil, organic composts and peat moss as plant fibers, a water retainer and a soil improver. Peat moss can usually provide necessary natural fibers and organic materials in soil. Especially, peat moss can absorb up to 25 times its own weight in water and is therefore valued as a water retainer to prevent drying effect of vegetation base materials which can harm the growth of vegetation in mattresses. Normally mattress systems resist the lateral earth pressures or stream power by their own weight. Therefore, filled materials must have suitable weight, compressive strength and durability to resist the loading, as well as the effects of water and weathering. In this project, 100 to 200-mm clean, hard stones were basically specified, and about 50-mm rubbles were also used. Test application of new mattress system carried out in the stream bank of a small stream in the Gwangreung experimental forest, belonging to Korea Forest Research Institute (KFRI) in December 16th, 2006. As a result of the monitoring of vegetation coverage of test application plots (each plot size is 4 by 2 m), the coverage of all plots reached 100% in the end of May, 2007 (approximately 50 days passed after the first gemination of vegetation). The coverage of the plots using big hard stones and organic composts and the plots containing peat moss increased more rapidly. The results show that peat moss is effective to retain soil moisture and establish more sound environment for vegetation gemination.

• Journal of Internet Computing and Services
• /
• v.12 no.6
• /
• pp.43-51
• /
• 2011

The recent development of the technology for wireless mobile computing and applied technology for location-based services has made it possible to support query processing faster than that in the past. However, some technological limitations on hardware and software still exist. The most critical aspects of query processing are accuracy and speed. For improving the accuracy, it is required that detailed information on the data involved in query processing be saved. In this case, the amount of information on the data increases, which decreases the speed. On the other hand, for increasing the speed, it is necessary to reduce the broadcast cycle, which enables rapid data acquisition as desired. In this case, because of insufficient index information, the listen time for the client increases, which may cause unnecessary energy consumption. Therefore, a trade-off occurs between the accuracy and speed. This paper proposes a hierarchical bitmap-based spatial index (HBI) as a solution for the aforementioned problems. HBI describes an object with 0 and 1 on the Hilbert curve map. It reduces the broadcast cycle by decreasing the index size on the basis of bit information and tree structure. Therefore, it is able to shorten the listen time and query processing time. In addition, HBI enables the detection of the locations of all the objects so that it is possible selectively listen to a broadcast. A performance evaluation of the proposed technique demonstrates that it is excellent.