Equo-Tip경도값에 미치는 실험변수의 영향

남승훈,전승범,김종집 ( S . H . Nahm,S . B . Jeon,J . J . Kim ) 한국열처리공학회 1990 熱處理工學會誌 Vol.3 No.2

For the accurate measurements of hardness in a material, it is necessary to have a thorough understanding of the effects of test variables on the accuracy of hardness value. For the rebound hardness test, major test variables are the radius of hammer ball tip, type of backing materials, size and roughness of the specimen. In this study, effects of these variables on Equo-Tip hardness value were investigated. Hardness measurements were carried out using WC balls with various sizes of worn-ot zone. The sample materials chosen for the experiments were commercial standard hardness blocks and SM45C steel bars subjected to either normalization or quench and temper treatments. As backing materials, aluminum, steel and rubber plates were used in all the experiments. Experimental results show that for the accurate measurements of Equo-tip hardness, it is necessary to use the hammer ball with a worn-out zone parameter of less than 0.23, and the recommended minimum thickness and width of the specimen are 25㎜ and 70㎜, respectively. Further for the surface preparation, the specimens need to be polished with an emery paper of No. 400 or finer, and for the backing matrials, it is recommended to use steels or rubbers.

일본 중앙즉응집단의 특성과 군사전략적 함의

남승훈 육군군사연구소 2018 군사연구 Vol.- No.145

In today's complex and uncertain Northeast Asian security environment, Japan is looking for change to a 'normal nation'. The international public opinion is divided about the Japan's change. However, R.O.K should pay close attention to these changes in Japan. Because Japan is a country that has a common alliance and common threats with R.O.K. From this point of view, this study was analyzed about the Japan's central readiness force. Specifically, this study examines the present position of Japan's military strategy based on 'integrated maneuvering defense force' today, and studies the details of the Central readiness force organization that plays a key role in such Japanese military strategy. Through this, I evaluated the actual power projection capability that exists behind Japan's active security movement today. The Central readiness force was created for purpose of 'international contribution', but it is a different type of unit than a defensive unit like the existing Japan's Self-defense-force. In this sense, the Japanese Central readiness force is also a 'double-edged sword' that raises concerns about in R.O.K and neighboring countries. In addition, the characteristics of the Central readiness force also provide important implications for R.O.K troops, who are now becoming 'game changers' on the Korean peninsula. Therefore, in this study, provides military strategic implications of conventional deterrence, strategic paralysis, and integrated cooperations. 오늘날 복잡하고 불확실한 동북아 안보환경 속에서 일본은 ‘보통국가’로의 변화를 모색하고 있다. 이러한 일본의 움직임에 대한 국제사회의 여론은 분분하다. 하지만 한국은 이러한 일본의 변화를 경계하면서도 주의 깊게 살펴볼 필요성이 있다. 그 이유는 일본은 한국과 공동의 위협과 공동의 동맹을 갖고 있다는 특성 때문이다. 이러한 관점에서, 본 연구는 2007년 일본 육상자위대 예하에 창설된 부대인 중앙즉응집단에 대하여 살펴보았다. 구체적으로 본 연구는 오늘날 통합기동방위력을 바탕으로 한 일본 군사전략의 현 주소를 살펴보고, 이러한 전략의 핵심 축을 담당하는 중앙즉응집단의 세부 특성을 알아보았다. 이를 통해 오늘날 일본의 적극적 안보행보 이면에 존재하는 실질적인 전력투사 능력을 평가하였다. 중앙즉응집단은 ‘국제공헌’을 목적으로 창설되었지만, 기존 자위대와 같은 방어적 성격의 부대와는 다른 형태의 부대라고 할 수 있다. 특히 중앙즉응집단의 특성인 기동성과 특수성은 오늘날 일본의 새로운 방위개념을 실현할 수 있는 핵심적인 수단임을 의미한다. 이러한 의미에서 일본 중앙즉응집단은 한국과 주변국들에게 일본 군사력에 대한 우려를 자아내는 ‘양날의 칼’과 같은 존재이기도 하다. 또한, 중앙즉응집단이 가진 재래식 억제와 전략적 마비능력과 같은 군사전략적 측면에서의 적실성, 그리고 협동성을 강화할 수 있도록 조직된 중앙즉응집단의 군 구조 형태는 한국군에게 중요한 시사점을 제공해 주고 있다. 따라서 이러한 중앙즉응집단의 특성을 벤치마킹하여 한국군에 적용한다면 전쟁의 목적, 수단, 범위가 제한된 현대전에서 더욱 효과적인 능력을 발휘할 수 있을 것으로 예상된다.

산업설비 안전관리기술

남승훈,백운봉 대한기계학회 2018 기계저널 Vol.58 No.6

순동의 고온에서의 크리프 균열성장 특성 ( Characteristics of Creep Crack Growth in Pure Copper at Elevated Temperature )

남승훈,김엄기,정민우,서창민 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.1 No.1

전기비저항을 이용한 금속합금 열화도 평가기술

남승훈,유광민,류제천 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.5

재료의 노화에 의한 강도 및 인성 감소치를 정량적으로 평가하는 비파괴적 기법의 개발이 시도되고 있으며 전기비저항법도 그 중의 하나이다. 본 연구에서는 전기비저항법의 열화도 평가에의 적용성을 살펴보기 위해 먼저 6종 10 가지의 비자성 금속을 측정시료로 선택하여 직류 two-point probe법(혹은 2탐침법)으로 전기비저항을 계산한 결과와 비접촉식 와전류 방법으로 전기비저항을 측정한 결과를 서로 비교하였다. 또한, 1Cr-1Mo-0.25V강에 대하여 비파괴적 측정 방법인 four-point probe 방법(혹은 4탐침법)을 사용하여 얻은 결과와 기존의 2탐침법을 사용하여 얻은 결과를 서로 비교하여 현장에서의 4탐침 기술의 적용 가능성을 살펴보았다. 1Cr-1Mo-0.25V강에 대하여 2탐침법으로 구한 비저항값과 4탐침법으로 구한 비저항 측정값의 차이는 0.6%였다. 따라서 4탐침법을 사용하여 현장에서 금속소재의 열화도의 비파괴적 평가가 가능하다고 사료된다. Developments of nondestructive evaluation techniques for reduction of strength or toughness by aging of material have been carried out, and the method using electrical resistivity is one of them. In this study, to examine the application of electrical resistivity to the evaluation of the evaluation of degradation of metallic alloy, ten different non-magnetic materials were selected as test materials. Electrical resistivities measured by DC two-point probe method and those measured by non-contact type eddy current method were compared with each other. In addition, to examine the application possibility of four-point probe technology in field, the electrical resistivities for 1Cr-1Mo-0.25V steel measured by DC two-point probe method and four-point probe method were compared with each other. Differences between two measure values for the 1Cr-1Mo-0.25V steel were0.6%. Therefore, the four-point probe method can be applied to the estimation of the degradation of metallic alloy.ect.

부가응력과 반발경도와의 관계

남승훈,김시천,전승범 ( S . H . Nahm,S . C . Kim,S . B . Jeon ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.4

Information of change of hardness values during applying load is needed often to control the quality of metal products efficiently, but the relation between applied stress and hardness has not been established. In this paper the theoretical relation between the rebound hardness and stress was examined briefly and the experiment was performed with some materials. Materials used in test were mild steel(SB41), 7-3 brass and copper, which were widely used in the commercial plants. Hardness was measured during stress applied using the Equo-Tip hardness tester as a kind of rebound hardness tester. Hardness values decreased as tensile stress increased, the decreasing rate was effected by the Young`s modulus of each material, and the rebound hardness values showed linear relationship with the applied stress in elastic region.

열화된 1Cr-1Mo-0.25V강의 DBTT 크기효과 보정에 관한 연구

남승훈,김엄기,이대열,Nam, Seung-Hun,Kim, Eom-Gi,Lee, Dae-Yeol 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.12

Miniaturized specimen technology is useful to characterize the mechanical behavior when it is difficult to sample the material enough for the test. In this study, two kinds of miniaturized Charpy impact specimens(i.e., miniaturized specimen with side groove and without side groove) of aged 1Cr- lMo-0.25V steel were prepared and tested. The relationship between the extent of degradation in terms of ductile brittle transition temperature(DBTT) and the fracture stress of 1Cr-1Mo-0.25V steel was established. The fracture stress obtained from miniaturized specimen without side groove turned out to be linearly related with the DBTT of standard specimen. Therefore the fracture toughness of aged turbine rotor steel might be evaluated by the fracture stress. In addition, the correlation between DBTT of standard specimen and that of miniaturized specimen was investigated. As the results of normalizing DBTT by maximum elastic tensile stress, the normalized DBTT of miniaturized specimen without side groove allows one to estimate that of standard specimen.

영상처리기법을 이용한 표면균열길이 측정 ( Measurement of Surface Crack Length Using Image Processing Technology )

남승훈,김용일,김시천,류대현 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.1 No.1

소형 샤르피 충격시험편에서의 파괴응력에 관한 연구 ( A Study on the Fracture Stress in Miniaturized Charpy Impact Specimens )

남승훈,김엄기,이대열,김시천 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.1 No.1

Environmental Impact Assessment of Composite Small Craft Manufacturing Using the Generic Work Breakdown Structure

남승훈,이동건,정용국,Philippe Lee,신종계 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.4

The number of studies on the environmental impact of products and services has increased in order to protect the environment. Recently, environmental impact assessments (EIA) and life cycle assessments (LCA), typically used for evaluating environmental impacts, have been gaining in popularity. Accordingly, this study performed an EIA using LCA methodology focusing on the manufacture of composite small craft. A work breakdown structure (WBS) is used in most shipyards to manage the overall life cycle of a craft. Therefore, for the EIA performed as part of this study, the generic WBS for environment (GWBSE) was defined by utilizing existing shipyard information. Unlike a general WBS with a determined structure, the GWBSE structure supports different combinations depending on the objectives; the EIA can be performed by combining different methods, materials, and product structures used in the manufacturing process for composite craft. Further, this study developed an application to effectively perform EIA utilizing GWBSE. The EIA was performed according to the manufacturing method and the combination of materials used for small leisure craft; the results were then analyzed.