Expensive PCBN or ceramic cutting tools are used for processing of difficult-to-cut materials such as Ti and Ni alloy materials. These tools have the problem of breaking easily due to their high hardness but low fracture toughness. To solve these problems, cutting tools that form various coating layers are used in low-cost WC-Co hard material tools, and research on various tool materials is being conducted. In this study, binderless-WC, WC-6 wt%Co, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are densified using horizontal ball milled WC-Co, WC-Co-Mo2C powders, and spark plasma sintering process (SPS process). Each SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co- 2.5 wt% Mo2C hard materials are almost completely dense, with relative density of up to 99.5 % after the simultaneous application of pressure of 60 MPa and almost no significant change in grain size. The average grain sizes of WC for Binderless- WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are about 0.37, 0.6, 0.54, and 0.43 μm, respectively. Mechanical properties, microstructure, and phase analysis of SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are investigated.

Tungsten carbide (WC) hard materials are used in various industries and possess a superior hardness compared to other hard materials. They have particularly high melting points, high strength, and abrasion resistance. Accordingly, tungsten carbide hard materials are used for wear-resistant tools, cutting tools, machining tools, and other tooling materials. In this study, the WC-5wt.%Co, Fe, Ni hard materials are densified using the horizontal ball milled WC-Co, WC-Fe, and WC-Ni powders by a spark plasma sintering process. The WC-5Co, WC-5Fe, and WC-5Ni hard materials are almost completely densified with a relative density of up to 99.6% after simultaneous application of a pressure of 60 MPa and an electric current for about 15 min without any significant change in the grain size. The average grain size of WC-5Co, WC-5Fe, and WC-5Ni that was produced through SPS was about 0.421, 0.779, and 0.429 μm, respectively. The hardness and fracture toughness of the dense WC-5Co, WC-5Fe, WC-5Ni hard materials were also investigated.

북한의 수자원 현황을 분석하고 미래를 전망하는 일은 수자원 분야 전문가들의 공통 관심사 중 하나이다. 그러나 북한의 폐쇄적인 정책으로 인해 수자원에 대한 정보를 획득하기 매우 어려운 현실이다. 이에 대한 대안으로 위성으로부터 획득한 정보와 글로벌 지형정보를 이용하면 개략적으로나마 북한의 수자원 또는 홍수로 인한 재해에 대해 확인할 수 있다. 본 연구는 위성으로부터 유도된 위성강우 자료와 글로벌 지형자료를 활용하여 대표적인 비접근 지역인 북한지역의 청천강 상류에 위치한 동신군 지역을 대상으로 유출분석을 수행하는 것을 목적으로 하였다. 언론보도에 나타난 북한지역의 2013년 7월 19일부터 21일 사이에 북한의 기상수문국 통보에 의하면 자강도의 동신군 413mm, 송원군 383mm, 희천시 322mm의 폭우가 쏟아졌다고 보고하고 있다. 이 시기의 위성으로부터 유도된 강우자료인 GSMaP_NRT자료에서는 최대 173.2mm, 유역 평균 160.3mm 정도의 강우가 발생한 것으로 제시하고 있다. 이는 Xie 등(2011)에 의하면 2000-2009년의 10년간의 연평균 강수량에 대하여 CMORPH자료를 분석한 결과 공간분포 패턴은 매우 잘 반영하고 있으나, 열대 및 아열대 지역에서는 과대 산정되고 중간 및 고위도 지역에서는 과소하게 산정되는 것으로 발표한 바 있어 본 연구에서 사용한 위성강우도 같은 결과를 제시하고 있다. 이 위성강우자료와 글로벌 지형자료인 Aster GDEM, GLCC자료를 이용하여 유출분석을 수행한 결과 첨두유출이 957.6㎥/sce의 유출이 발생한 것으로 분석되었다. 향후 위성강우의 정확도 평가와 위성강우와 지점 및 레이더를 이용한 보정을 통해 보정된 시계열 자료를 생산하여 유출분석을 수행할 계획이다.

This April 5th dam and Hwanggang dam, which are located in Imjin river, North Korea, become the main causes of water shortages and damages in Imjin river downstream. April 5th dam is assumed a small or medium-sized dam, its total storage volume reaches about 88 million ㎥. And Hwanggang dam, multi-purposed dam of total storage volume approximately 0.3 billion ㎥ to 0.4 billion ㎥ is used as source of residental or industrial water in Gaeseong Industrial Complex. North Korea, which has April 5th dam and Hwanggang dam in Imjin river, manages water of approximately 0.39 billion ㎥ to 0.49 billion ㎥ directly. As water is storaged or discharged through dam, it causes a severe damage to areas in Yeoncheon-gun and Paju city, South Korea. Therefore, this study intends to analyze and estimate runoff through dam construction by using hydrological observation data and artificial data such as service water supply and agricultural water in Imjin river, water shortage and damage correctly.

The meaning of integration is creation of new characteristics by integration of different elements. The meaning of integration is different from case to case, from simple mixing two different characteristics, to the best, perfect integration. Traditionally integration is integration of different subjects so as to teach effectively and efficiently in contrast to teach each subject independently. Here I would like to conceptualize the integration as the integration of internal world of the learner rather than the external world. The integration of subject is classified as multidisciplinary, interdisciplinary and transdisciplinary approaches. Integration in a single subject is integration of cognitive, psychomotor, and affective domains, integration of unit among some subjects and integration of real life situation. The strong points for integration are to provide quality of education that can have perspectives for the meaning of life, provide accustomed teaching & learning environments. Also it is afformative effect to integrate cognitive, psychomotor and affedtive domain. The shortcomings of integration is the loss of the system of contents for teaching for coresponding subject, time consuming teaching and learning activities in classrooms, limitation of concepts or contents introduced in the classroom for teaching, lack of materials to support the integrated approach and difficulty of developing curriculum and related materials. The strategies for integrations are activity centered learning, respect for the selection of students, respect for the interests and concern of students, approach for the problem centered learning, stress relationship of related subject. Also examplary materials of integrations are provided for deeper understanding of integration.