• 한국분말재료학회지
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• 제31권1호
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• pp.37-42
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• 2024

Friction stir spot welding (FSSW) is a solid-state joining process and a rapidly growing dissimilar material welding technology for joining metallic alloys in the automotive industry. Welding tool shape and process conditions must be appropriately controlled to obtain high bonding characteristics. In this study, FSSW is performed on dissimilar materials AA5052-H32 aluminum alloy sheet and SPRC440 steel sheet, and the influence of the shape of joining tool and tool insertion depth during joining is investigated. A new intermetallic compound is produced at the aluminum and steel sheets joint. When the insertion depth of the tool is insufficient, the intermetallic compound between the two sheets did not form uniformly. As the insertion depth increased, the intermetallic compound layer become uniform and continuous. The joint specimen shows higher values of tensile shear load as the diameter and insertion depth of the tool increase. This shows that the uniform formation of the intermetallic compound strengthens the bonding force between the joining specimens and increases the tensile shear load.

• 한국강구조학회 논문집
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• 제28권3호
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• pp.151-162
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• 2016

본 연구는 합성보와 하이브리드보의 장점을 활용한 신형상 하이브리드 합성보의 형상을 개발하였으며, 그 중 춤이 작은 형상의 휨성능을 검증하기 위해 12개의 휨 실험체를 제작하여 단조가력 실험을 진행하였다. 휨성능 실험결과, 공칭하중에 대한 실험체 최대하중의 비는 평균 1.24배로 안정적인 내력을 확보하였으며, 합성보의 내력평가는 기존 합성보 내력평가식(KBC 2009)을 적용 가능한 것으로 판단된다. 또한 하부강판에 고강도강($F_y=650MPa$) 적용 시 소재의 기계적 특성 및 구조성능에 대한 충분한 사전검토가 필요할 것으로 판단된다.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1931-1940
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• 2014

x본 논문에서는 키넥트(Kinect) 시스템에서 획득한 깊이 영상으로부터 convex-hull을 이용한 기하학적 특징 기반의 손 모양 인식 기법을 제안한다. 키넥트 시스템은 깊이 영상과 사용자의 골격 정보를 제공하는 카메라로 손 영역 검출에 유용하게 활용할 수 있다. 제안하는 기법에서는 키넥트로 획득한 깊이 영상에서 손 영역을 검출하고, 이 손 영역의 convex-hull을 구한다. 손 모양에 따라서 변하는 convex-hull에서 잡음으로 생긴 경계점 및 인식에 불필요한 경계점을 일련의 기법을 통해 제거한다. 추려진 경계점을 통해 재구성된 convex-hull을 특정 다각형으로 판단하고, 이 다각형의 내각의 합을 이용하여 손 모양을 인식하게 된다. 실험을 통해 제안하는 기법이 인식하고자 하는 모델에 대하여 높은 인식률을 보여준다는 것을 확인하였고, 단순히 특정 방향으로 고정된 손 모양뿐만 아니라 같은 모양이나 방향이 틀어진 손 모양에 대해서도 우수한 인식 성능을 확인하였다.

• 한국산업융합학회 논문집
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• 제7권2호
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• pp.153-159
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• 2004

The purpose of this research is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area, the depth and shape of the piston top cavity (main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. And another purpose of this research is to make a new diesel engine that is satisfied fuel consumption and regulation value of exhaust gas. 1. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load than low speed and low load. The influence of jet passage large area was proven to decrease the rate of fuel consumption. 2. Smoke was affected significantly by the depth of the piston top cavity, but exhaust temperature and the rate of fuel consumption wasn't affected. The rate of fuel consumption was affected by changing injection timing. 3. The rate of fuel consumption, exhaust temperature and Smoke were affected significantly by the shape of the piston top cavity from rectangular to trapezoid. That is we have all high value. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions. 4. We made a new diesel engine that is satisfied design target values(sfc=190 g/hr, NOx + THC=6.0 g/KWh, PM=0.3 KWh), the rate of fuel consumption and emission standard etc., through changing injection timing at the maximum torque point and rated power point. Although we have a little high NOx value.

• 한국강구조학회 논문집
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• 제28권6호
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• pp.403-414
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• 2016

최근 강재가격 하락과 인건비 상승으로 강구조 및 합성구조의 연구가 활발히 진행되고 있다. 이에 본 연구에서는 보 춤이 큰 고성능 하이브리드 합성보에 대해 10개의 실험체를 제작하여 휨성능을 평가하였다. 휨 실험 결과 공칭하중에 대한 최대하중의 비($P_u/P_n$)는 평균 1.19배로 안정적인 내력을 확보하였으며, 변형능력(${\delta}_{0.8P_u}/{\delta}_y$)은 약 3.9~4.5배의 범위로 확인되었다. 또한 하이브리드 합성보의 내력평가는 현행 건축구조기준(KBC 2009)을 적용하여 평가하는 것이 적절한 것으로 판단된다.

• 한국기계가공학회지
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• 제12권6호
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• pp.159-166
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• 2013

In order to develop the optimum shape of an MQL carbide end-mill suitable for high speed machining of wing ribs which are a detailed part of larger wing structures, using a new material Al-Li alloy, a new MQL carbide end-mill is created that has various quantities of holes, hole sizes, and hole locations. A theoretical machining graph is generated using the hammer test and FRF simulation, and a machining test is performed in order to verify the machining stability in the high speed machining area. The optimum configuration of the MQL carbide end-mill is also presented through comparing the chattering, machining noise and cutting conditions, including the maximum cutting depth, rpm, and feed rate per teeth, for each cutter.

• Animal Systematics, Evolution and Diversity
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• 제31권3호
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• pp.141-145
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• 2015

A new marine sponge, Antho (Acarnia) seogwipoensis n. sp., of the family Microcionidae, was collected from Seogwipo-si, Jeju-do, Korea, about 100 m in depth using a gill net on 1969. The genus Antho Gray, 1867 including Demospongiae, Poecilosclerida, Microcionidae, is a large group of sponges. About 100 species in Antho were reported from worldwide. The genus Antho contains five subgenera: Antho, Acarnia, Isopenectya, Jia, and Plocamia. Among them, about 30 species in Acarnia were described in world sponge. A new sponge's body shape is branching, size up to 124 mm wide, 213 mm high, 3-8 mm thick in branch and 7-9 mm thick in stalk. Antho (Acarnia) seogwipoensis n. sp. is similar to A. (A.) novizelanicum Ridley and Duncan, 1881 based on their spicules type and skeletal structure, but differs in the spicules dimension and growth form. This new species is branched growth form and have three kinds of toxa.

• Journal of Welding and Joining
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• 제33권4호
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• pp.7-16
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• 2015

New lasers such as high power, high brightness and short wavelength laser are using diverse industry. Also new technologies are developing actively to solve various issues such as spattering, process monitoring, deep penetration and key-hole stability. ICALEO is the international congress where recent technology for laser material processing and laser system are present. At 2014, it was held at San Diego in USA and more than 260 papers were presented from 28 country. The effect of the laser beam shape such as Gaussian like and top-hat was investigated on acoustic emission signal and pore formation in welding. Inline penetration depth was measured with ICI(Inline Coherent Imaging) technique and the data was verified with real time X-ray image on laser welding. The laser welding performance at low pressure environment was evaluated for the thick plate alloy steel. UV laser was used to weld various metals such as Cu, Aluminum, steel and stainless steel. The effect of the wavelength of the laser on the formation of the wave at the wall of the key-hole front and the absorptivity was investigated.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.2043-2050
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• 2014

X-선 탐지장치는 검색 대상물에 대한 단면 정보만을 제공하기 때문에 내용물에 대한 판정의 한계가 있다. 스테레오 X-선 탐지 장치는 검색 대상체에 대한 단면 정보와 논문에서 제안된 볼륨기반의 3차원 형상복원 알고리즘을 통해 3차원 정보를 제공하여 검색효율을 높일 수 있다. 또한, 고속 검색을 위해 자동화 검색에 대한 식별자로 형상복원 결과를 적용하고자 유사한 모형의 15개 샘플에 대한 형상 복원 및 검출율을 분석하였다. 검색대상 모델에 대한 복원 결과는 실측 모델과 비교할 때 각각 폭 (2.56%), 높이 (6.15 %)와 깊이 (7.12 %)의 오차를 보이며 높은 정확도를 나타내었다. 또한 K-Mean 클러스터링 알고리즘을 적용하여 실험한 결과 97 %의 검출 효율이 보였다. 본 논문의 결과는 자동화 시스템을 위한 새로운 검색식별자를 제시하며 추가연구를 통해 검색 시스템의 효율성 향상을 위한 연구를 진행할 것이다.

• 콘크리트학회논문집
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• 제11권4호
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• pp.129-136
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• 1999

For the prediction of concrete-steel bond ability in reinforced concrete, many countries establish specifications for the pullout test. But these methods hardly to consider many parameters such as strength, shape, diameter and location of steel, concrete restrict condition by loading plate, strength of concrete and cover depth etc, and it is difficult to solve concentration and disturbance of stress. The purpose of this study is to propose a New Ring Test method which can be rational quantity evaluations of bond splitting mechanism. For this purpose, pullout test was carried out to assess the effect of several variables on bond splitting properties between reinforcing bar and concrete. Key variables are concrete compressive strength, concrete cover, bar diameter and rib spacing. Failure mode was examined and maximum bond stress-slip relationships were presented to show the effect of above variables. As the result, it appropriately expressed general characteristics of bond splitting mechanism, and it proved capability for standard test method.