• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.313-318
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• 2013

Magnetic abrasive polishing is an advanced deburring process for nonmagnetic materials and micropattern products that have non-machinability characteristics. Despite these advantages, there are some problems with using MAP for deburring. MAP has introduced geometric errors into microgrooves because of an over-cutting force caused by uncontrolled magnetic abrasives in the MAP tool. Thus, in this study, to solve this problem, an EP (electrolyte polishing)-MAP hybrid polishing process was developed for deburring microgrooves in an STS316 material. In addition, an evaluation of EP-MAP for the deburring of microgrooves was carried out by profiling the burrs. The results of the experiment showed geometric errors after the deburring process using MAP. However, in the case of EP-MAP, no geometric error was observed after the process because of the lower material removal rate in EP-MAP.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.581-589
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• 2019

Guided missiles assembled with the bolted joint are subjected to various shock loading conditions while flying in the air and operating on the ground or platform. Especially, It is important to analyze the effect of the shock load on the structure because it affects the structure for a short duration time while its acceleration magnitude is quite large. In this study, mechanical shock tests on the structure with the bolted joint have been carried out to measure the acceleration changes of the structure against external shock loads by electrical exciter. Variation of dynamic characteristics of a structure with fastening methods and fastening forces has been investigated through Shock Response Spectrum analysis.

• The Korean Journal of Applied Statistics
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• v.35 no.5
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• pp.593-601
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• 2022

We call "fruad" the cases that are not frequently occurring but cause significant losses. Fraud detection is commonly encountered in various applications, including wafer production in the semiconductor industry. It is not trivial to directly extend the standard binary classification methods to the fraud detection context because the misclassification cost is much higher than the normal class. In this article, we propose the functional fraud detection support vector machine (F²DSVM) that extends the fraud detection support vector machine (FDSVM) to handle functional covariates. The proposed method seeks a classifier for a function predictor that achieves optimal performance while achieving the desired sensitivity level. F²DSVM, like the conventional SVM, has piece-wise linear solution paths, allowing us to develop an efficient algorithm to recover entire solution paths, resulting in significantly improved computational efficiency. Finally, we apply the proposed F²DSVM to the defective wafer detection problem and assess its potential applicability.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.1
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• pp.9-20
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• 1987

지난해 우리나라는 주요 10대업종중 <조선>과 <건설>을 제외하고 대부분의 업종이 3저의 영향으로 생산, 내수, 수출등 제분야에서 고루 균형을 가진 호황의 한 해였다. 우리나라는 본원적으로 부존자원이 없는데다가 외채자본에 의존한 결과, 경제적 자립성을 유지하기 위해서는 부득이 해외시장에 의존하지 않을 수 없다. 그러기 때문에 정부는 지 금까지 수출주도형 고도성장정책을 견지해 왔으며 이 결과 국제수지의 적자와 물가상승등 부작용이 뒤따른것도 사실이다. 아뭏든 지난해의 우리나라 경제를 요약하면 경제성장- 물가안정-국제수지흑자로 이어졌는데 결국 세마리의 토끼를 한꺼번에 잡은 행운의 한 해 였음이 분명하다. 특히 값진 보람이라고 한다면 지금까지의 만성적인 국제수지적자가 추 방되고 사상초유의 흑자원년을 기록했다는 사실이다. 이렇게 볼 때, 우리기업인들은 행운이였다고 하기 이전에 주어진 기회를 재빠르게 포착하여 이용했다는 사실에서 그 저력을 과시하는 표현이 더욱 적절할 것 같다. 금년에도 또 몇마리의 토끼를 잡기 위해서는 고속성장보다는 안정된 기조하에서 수출주도형의 경제정책이 계속 밀고나가야할 것으로 생각 된다. 3저현상은 무한히 지속하는 것이 아니며 언제 무산될지 모르는 미래에 대비하여 사전 에 그 대응책이 마련되어야 하며 이 처방은 경쟁 우위력에서 구해내야할 것이다. 따라서 우리 는 축적된 경험과 <노우하우>를 바탕으로 품질의 고급화, 생산성향상, 부가가치의 증진등으로 선진국 대열에 진입할 수 있는 힘을 키워야 하며 이것은 오직 노사협조라는 평범한 진리에서 얻을 수 있다. 금년도 년초에 대통령의 국정연설에서 <올해는 우수한 기술. 기능인이 대폭 육성되고 이들이 산업현장에서 자기의 꿈을 키울 수 있도록 더욱 효과있는 지원제도를 발전해 나갈 것이다...>라고 하였고 또 <이같은 과학기술의 진흥과 산업현장의 기술. 기능인력을 양 성하는 데 역점을 둔다...>는 최고지도자의 구상은 바로 우리가 기대했던 공감대를 형성하였 다고 본다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.1
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• pp.63-69
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• 2013

Many researchers are trying to reduce the use of lubrication fluids in metal cutting to obtain safety, environmental and economical benefits. The aim of this study is to determine the optimization lubrication conditions in minimum quantity lubrication(MQL) turning of workpieces with taper angle. This study has been considered about various conditions of MQL. The objective functions are cutting force and surface roughness. Design factors are nozzle diameter, nozzle angle, MQL supply pressure, distance between tool and nozzle and length of supply line. The cutting force and surface roughness were statistically analyzed by the use of the Box-Behnken method. As a results, optimum lubrication conditions were suggested and verification experiment has been performed. The results of this study are expected to help the selection of lubrication conditions in MQL turning.

• Food Engineering Progress
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• v.22 no.4
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• pp.381-385
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• 2018

Various rheological methods to measure the hardness of instant cooked rice by a texture analyzer were investigated and compared. Specifically, instant white rice samples with a wide range of hardness were subjected to four different rheological tests with disk, cylinder, rod, and cone probe whose results were inter-correlated. All the measurements demonstrated that the hardness of instant rice was reduced with increasing moisture content and showed negatively linear relationships. Out of the four tests applied in this study, the highest coefficient of correlation ($R^2=0.9268$) was observed distinctly in the cone probe test, where both compressive and shear forces can be applied to deform individual rice grains. However, the cylinder probe test had the lowest coefficient of correlation ($R^2=0.7247$) because it may be ineffective in causing direct deformation of individual rice grains. Furthermore, when the hardness values (N) were converted to stress (Pa), highly linear correlations ($R^2{\approx}0.99$) were observed between the tests with similar probe geometry and force application.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.225-230
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• 2020

This paper highlights the influence and the importance of the syntactic-grammatical knowledge on "the reading machine", appeared in Jackendoff (1999). Due to the lack of the detailed testing and implementation in his research, this paper tests an extensive data array using a component of Google Translate, currently available freely and most widely on the internet. Although outdated, Jackendoff's paper, "Why can't Computers use English?", argues that syntactic-grammatical knowledge plays a key role in the outputs of computers and computer-based reading machines. The current research has implemented some testings of his thought-provoking examples, in order to find out whether Google Translate can handle the same problems after two decades or so. As a result, it is argued that in the field of NLP, I-language in the sense of Chomsky (1986, 1995 etc) is real and the syntactic, grammatical, and categorial knowledge is essential in the faculty of language. Therefore, it is reassured in this paper that when it comes to human language, even the most advanced "machine" is still no match for human faculty of language, the syntactic-grammatical knowledge.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.172-174
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• 2011

표면경도와 내마모특성을 가진 질화처리는 다양한 철강재료에 적용되고 있다. 플라즈마를 이용한 질화법은 다른 질화처리법에 비해 처리시간이 짧고 폐수 및 배기가스와 같은 오염물질의 발생이 거의 없어 친환경적이며 낮은 온도에서 처리가 가능하기 때문에 변형 및 금속학적 물성의 변화가 없는 것이 특징이다. 한편 DLC 처리법은 물리화학적 특성이 다이아몬드와 유사하면서도 저온 합성이 가능하고, 표면이 평활하다는 합성기술상의 장점을 가지고 있기 때문에 많은 분야에서의 응용이 연구되고 있는 재료이다. 특히 고경도, 고윤활성 등의 물리적, 화학적, 광학적 특성과 화학적 안정성과 신체적합성 등의 특성으로 인해 기계부품, 공구, 광학기기, 전자부품, 자동차부품과 의료용 기기분야 등에 적용하고 있다. 본 연구에서는 질화처리 및 DLC 처리를 한 챔버내에서 동시처리하여 그 특성을 평가하였다. 이와같이 얻어진 처리물을 Field Emission Scanning Electron Microscope를 이용하여 단면분석을 하였고, 시편의 경도는 나노인덴터로 측정하였다. ball-on-disk 방식의 마모시험기를 이용하여 내마모특성을 관찰하였으며, 접합력을 측정하기 위해 스크래치 테스트를 실시하였다.

• Composites Research
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• v.30 no.4
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• pp.241-246
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• 2017

The brittle nature in most FRP composites is accompanying other forms of energy absorption mechanisms such as fibre-matrix interface debonding and ply delamination. It could play an important role on the energy absorption capability of composite structures. To solve the brittle nature, the adhesion between pines and composites was studied. Thermal treated pines were attached on carbon fiber reinforced polymer (CFRP) by epoxy adhesives. To find the optimum condition of thermal treatment for pine, two different thermal treatments at 160 and $200^{\circ}C$ were compared to the neat case. To evaluate mechanical and interfacial properties of pines and pine/CFRP composites, tensile, lap shear and Izod test were carried out. The bonding force of pine grains was measured by tensile test at transverse direction and the elastic wave from fracture of pines was analyzed. The mechanical, interfacial properties and bonding force at $160^{\circ}C$ treated pine were highest due to the reinforced effect of pine. However, excessive thermal treatment resulted in the degradation of hemicellulose and leads to the deterioration in mechanical and interfacial properties.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2082-2089
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• 1992

An experimental study on forging an axi-symmetric dome type of AISI4130 was carried out using modeling material. In order to verify the validity of the experimental data, a similarity study between plasticine and AISI4130 has been made. Friction conditions were characterized by ring test for the various lubricants. For the closed-die forging experiments of an axi-symmetric dome type of AISI4130 using the plasticine, various cylindrical billets with different aspect ratios were forged and different flash width to thickness(W/T) ratios were used in order to determine the optimum forging conditions. As W/T ratios decrease forging loads decrease while excess volumes increase. It was found out that the experimental results reproduce the similiar results available in the literature. As a result of these experiments, it was construed physical modeling is an excellent tool for forging process simulation at a practical level.