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해수(海水)로부터 희유금속(稀有金屬) 회수(回收) 연구동향(硏究動向)
김종헌,노경란,김상우,최성배,길상철,Kim, Jong-Heon,Noh, Kyung-Ran,Kim, Sang-Woo,Choi, Sung-Bae,Kil, Sang-Cheol 한국자원리싸이클링학회 2013 資源 리싸이클링 Vol.22 No.6
Marine mineral resources are classified into submarine and seawater mineral resources. In seawater, huge amounts of useful minerals, such as uranium, lithium, magnesium, aluminum, zinc, iron, silver, copper, vanadium, nickel, titanium and cobalt are present. If the rare metals recovery technology from seawater is developed, the commercialization of the precess will be possible. For the 21st century, countries rich in resoures tend to weaponize the resources, according to the depletion of reserves and quality degradation of metal resources in the land. Therefore, Korea that relies on imports for most of the metal resources, should focus on the research and development of the rare metals recovery technology from seawater by using the geographical characteristics of the country that is on three sea-sides. 해양광물자원은 크게 해저면에 부존되어 있는 해저광물자원과 해수 중에 녹아 있는 해수광물자원으로 대별된다. 해수에는 막대한 양의 유용광물이 녹아 있어 회수기술 개발이 완료되면 상업화 가능성이 큰 것으로 알려져 있다. 21세기에 들어 육상금속자원의 저품위화 및 매장량 고갈에 따라 자원 보유국들이 자원을 무기화 하는 경향이 심화되고 있다. 따라서 대부분의 금속자원을 수입에 의존하는 우리나라는 삼면이 바다인 지리적 특성을 살려 해수로부터 희유금속 회수기술 개발에 적극적으로 나설 필요가 있다. 본 연구에서 해수로부터 희유금속 회수관련 논문분석 결과, 미국이 495편의 논문을 게재하여 양적 질적으로 가장 우수한 것으로 나타났다. 연구기관별로 보면 Chinese Acad. Sci.가 152편의 논문을 게재하여 양적으로 많은 연구가 이루어졌으며, 31편의 논문을 게재한 Univ. Oxford는 질적으로 가장 우수한 것으로 나타났다.
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평화로운 21세기를 위한 준비 : 지구적 안보의 도전과 신전략 Global Security and New Strategy
김종헌 부산 외국어 대학교 2000 外大論叢 Vol.20 No.1
Despite the disruption evident since the end of the Cold War, the great powers have yet to forge a clear, coherent strategy. for promoting gobal security. Instead, confusion and conflicting impulses abound. Form efforts to deal with the civil war in what was once Yugoslavia to coping with domestic turmoil in Somalia, their policics have been characterized by hesitation and false starts. The failure to prevent aggression stemming from long-suppressed ethnic hatreds, alongside percolating rivalries among themselves over trade issues, have heightened apprehensions about whether the great powers will be able to maintain peaccful relation in the long term. To xome extent, their struggles are understandable. Creating a global security policy for a chaotic and confusing post Cold War world is a formidable challenge. The simple bipolar system of the recent past rapidly is giving way to a more complex configuration of strength, and the prevailing uncertainty surrounding the great powers future intentions makes construction of a new security system difficult. In today's cloudy global atmosphere, military and economic might are becoming increasingly diffused. In contrast to bipolarity, where two superstates held a preponderance of strength compared to all other countries, the multipolar system of the future appears destined to contain as many as five roughly equal great powers: the U.S., China, Russia, Japan, and either Germany or a European Union with a common defense policy. A "power transition" is well under way, and the changes provoked by this redustribution promise to be fundamental. The relative capabilities of approximate parity. The diffusion of strength among the world's leading states demands attention because some previous forms of multipolarity have been more war-prone than others. For examples, the multipolar system of antagonistic blocs that developed on the of World War I proved particularly dangerous. When a world of many great powers splits into rival camps, there is little chance that competitors in one polocy arena will emerge as partners somewhere clse, so as to mitigate the competition. Rather, the gains made by other, ultimately causing minor disagreements to grow into larger face-offs from which neither coalition is willing to retreat. Since the international system of the early 21st century probably will include three or more extremely powerful states whose security interest are global, it is important that they do not become segregated into rival blocs. While the world can rejoice in the end of Cold War hostility, differences in the interest of the great powers have not disappeared and there is no assurance that future disagreement will not culminate in intense conflict. As former U.S. Security of State Lawrence S. Eagleburger warns, we are "returning to a more traditional and complicated time of multipolarity with a growing number of countries increasingly able to affect the course of events." The primary issues are how well the U.S. and Russia can adjust to their unequal decline from overwhelming preponderance and how well China, Japan and the European Union will adapt to their newfound importance. "The chance will not be easy for any of the players as such shifts in power relationships have never been easy." Can great-power cooperation, not renewed conflict prevail? At issue is whether the security threat that collectivly will face the world will be managed through multilateral great-power action instead of the unilateral pursuit of national advantage.
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김종헌,이한섭,홍대식,강창언 한국통신학회 1993 韓國通信學會論文誌 Vol.18 No.12
이 논문에서는 DS/SS(Direct Sequence Spread/Spectrum) 시스템에서 초기동기(aquisition)를 위해, 정합 필터의 출력중 부정합된 최대 상관값을 임계값(threshold)으로 결정하는 TDMMC(Threshold Decision from the Maximum Mismatching Correlation value) 알고리듬을 제안한다. PN코드는 주기성과 정합됐을 때의 상관값이 정합되지 않을 때의 상관값보다 크다는 성질을 가지고 있다. 기존의 방식은 위의 2가지 성질 중에서 후자에 기반을 두고 있는 반면, TDMMC는 위의 성질 둘 모두에 기반을 두고 있다. TDMMC의 궁극적인 목적은 수신기에서 신호 검파확률를 1에 가깝게 하는데 있다(Pd$\longrightarrow$1). TDMMC는 임계값 블록(threshold block)을 이용하여 S/N이 변함에 따라 적절한 임계값을 설정할 수 있다. 시뮬레이션 결과, 비동기식 DS/SS-CSK 시스템에 적용된 TDMMC는 기존의 방식에 비해 성능이 향상됨을 보여준다. An algorithm for the threshold decision from the maximum mismatching correlation value in a direct-sequence spread-spectrum system is presented. This algorithm is named the TDMMC(Threshold Decision from the Maximum Mismatching Correlation value). The purpose of the algorithm is to set the decision threshold in the system which will provide large probability of signal detection. Using this algorithm, the proper setting of the threshold for various SNRs is possible. An additional block called the Threshold Block is used to improve the system performance. The result from the computer simmulation has shown that appling the TDMMC to the noncoherent DS/SS-CSK system can achieve performance improvement.
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청양 지역에 분포하는 트라이아스기 후기의 조계리층에서 산출된 규화목 화석
김종헌,백승덕,이원국 공주대학교 과학교육연구소 2003 과학교육연구 Vol.34 No.-
충남 청양 지역에 분포하는 트라이아스기 후기의 조계리층에서 규화목 화석이 발견되었다. 규화목 화석의 산출은 남한에 분포하는 하부중생계 지층에서 최초의 기록이다. 분류학적 연구결과, 구과류에 속하는 Xenoxylon sp.와 Dadoxylon sp.의 2속 2종이 식별되었다. 본 논문에서 구과류 화석의 특징과 비교 및 그 의미에 대해서 고찰하였다. Petrified wood fossils are discovered from the Upper Triassic Jogyeri Formation distributed in the Cheongyang area. The occurrence of petrified fossils is the first record in the Lower Mesozoic strata distributed in South Korea. As a result of anatomical study of wood fossils, two specie belonging to two genera of Xenoxylon sp. and Dadoxylon sp. which belong to conifers, are recognized. This paper deals with the characteristics, comparison and significance of conifer wood fossils.
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탄화수소계(R290/R600a) 혼합냉매를 적용한 왕복동형 압축기 성능 해석
김종헌,정연구,박경우,박희용 대한설비공학회 1999 설비공학 논문집 Vol.11 No.2
A performance analysis simulation program that can be applied to a hermetic reciprocating compressor with various refrigerants has been developed. For the numerical analysis, the passage of refrigerant in compressor is subdivided into control volumes. Instead of the ideal gas assumption, CSD equation of state is applied to calculate the thermodynamic properties of refrigerants. To verify the validity of developed program, the result has been compared with the experimental data served by the compressor supplier. The performance of each refrigerant and the possibility of direct application are estimated by applying R12, 134a, R290, R600a and R290/R600a mixture to an existing compressor. Also, parametric study for various crank rotating speeds and the mole fractions of refrigerant has been performed.
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