• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.40-45
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• 2016

Interrupted cutting has different cutting characteristics compared with continuous cutting. In interrupted cutting, the workpiece has a groove that regularly impacts the cutting tool and workpiece. Therefore, tool damage occurs rapidly, and this increases the cutting force and surface roughness. In this study, we performed interrupted cutting of carbon steel for machine structure (SM45C) using a coated carbide tool (TT7100). To predict the cutting force, we analyzed the experimental results with a regression analysis. The results were as follows: We confirmed that the factors affecting the principal force and radial force were cutting speed, depth of cut, and feed rate. From the multi-regression analysis, we deduced regression equations, and their coefficients of determination were 89.6, 89.27, and 28.27 for the principal, radial, and feed forces, respectively. This means that the regression equations were significant for the principal and radial forces but not for the feed force.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.128-138
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• 1993

This study was carried out to improve forest tax system corresponding to Korean forestry status. Especially, special regard was paled in order to promote forest investment as a result of improvement measures. As a result of this study, the establishment of new system which allow deduction as a loss when forest investment occurred is more effective than present forest income tax system, which gives tax-exemption on cutting of artificial forests. Some detailed adoption technique of that system was examined in various viewpoint. Also, it is indicated that this improvement measures was already adopted generally in some developed countries.

• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.373-382
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• 2015

Purpose: In this paper, we developed a reliability index (RI) to efficiently compare reliability of products based on the design, development and production information such as reliability tests, quality, product life-cycle management. RI also can be applied to reliability prediction of a novel product as well as comparison evaluation among existing products. Methods: For evaluating RI, we proposed evaluation process which is composed of five steps. Target modules are selected based on warranty data and correlation analysis. Scores of selected target modules are calculated by scoring function. Finally, weights of RI model are determined by optimization method. Results: This paper presented an empirical analysis based on failure data of mobile devices. In this case study, we demonstrated that there is a direct correlation between evaluated RI and field failure probability of each product. Conclusion: We proposed the index for comprehensive and effective assessment of product reliability level. From the procedure of this study, we expected to be applied for reliability estimation of novel products and deduction of field failure-related factors.

• The Korean Journal of Applied Statistics
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• v.25 no.4
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• pp.669-680
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• 2012

Noise removal of document images is a necessary step during preprocessing to recognize characters effectively because it has influences greatly on processing speed and performance for character recognition. We have considered using the spatial filters such as traditional mean filters and Gaussian filters, and wavelet transformed based methods for noise deduction in natural images. However, these methods are not effective for the noise removal of document images. In this paper, we present noise removal of document images using support vector regression. The proposed approach consists of two steps which are SVR training step and SVR test step. We construct an optimal prediction model using grid search with cross-validation in SVR training step, and then apply it to noisy images to remove noises in test step. We evaluate our SVR based method both quantitatively and qualitatively for noise removal in Korean, English and Chinese character documents, and compare it to some existing methods. Experimental results indicate that the proposed method is more effective and can get satisfactory removal results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.641-650
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• 2000

The effects of noise and doppler for low orbit satellite range measurement using tone method are represented in this paper. Also the optimal noise bandwidth of range signal detection circuit which is used for range measurement system of KOMPSAT is proposed. Based on the effects of satellite orbit parameters via the deduction of dynamic motion characteristics of low orbit satellite and signal to noise spectral density of range measurement signal, the effects of noise and doppler for range measurement system are analyzed. The effect of satellite link noise is decreased, but the effect for doppler is increased as the PLL noise bandwidth of range signal detection circuit is increased. The validation of analyzed effect is verified via comparison of measurement results of KOMPSAT's range measurement system and simulation results in environments of low orbit satellite.

• Communications of Mathematical Education
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• v.23 no.2
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• pp.461-481
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• 2009

The semiotic approach to the mathematics education has been studied in last 20 years by PME, ICME conferences. New cultural developments in multi-media, digital documents and digital arts and cultures may influence mathematical education and teaching and learning activities. Hence semiotical interest in the mathematics education research and practice will be increasing. In this paper the basic ideas of semiotics, such as Peirce triad and Saussure's dyad, are introduced with some mathematical applications. There is some similarities between traditional research topics for concept, representation and social construction in mathematics education research and semiotic approach topics for the same subjects. some semiotic applications for an arithmetic problem for work, induction, deduction and abduction syllogisms with respect to Peirce's triad, its meaning in scientific discoveries and learning in geometry and symmetry.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.960-965
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• 2014

Transmission loss of specimen is calculated by measuring energy of incident and transmission and using reverberant room of large size. But normal measurement of transmission loss has trouble because it is actually demanded that large area and specimen of certain size is satisfied with condition of diffused sound field. Especially, in case of mechanical component, interested frequency band is mid-frequency band between 500 ~ 2k Hz, and it is used to be available to minimize a reverberation chamber under conditions satisfying acoustic one because production of specimen for transmission loss measurement has limit. But, as in semi-reverberation room, it is difficult to satisfy condition of diffuse sound field and modification factor is applied to complement that. Correction factor when measuring transmission loss using semi-reverberation chamber is required accuracy because it works as main factor determining reliability of reuslts on transmission loss. In this study, it is analyzed that an effect on correction factor based on varying materials and sizes of specimens in order to deduction of it. Also It is confirmed that applied by elicited correction factor with actual railway vehicle's floor has reliability.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1788-1792
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• 2007

한강 "수변구역"에서 비점오염물질의 공공수역 유입을 억제하기 위한 다양한 방법들 중에서 보편적이고 자연친화적인 방법은 다양한 생물의 서식공간이며, 동시에 본류로 유입되는 과정에서 수질을 정화시키는 수질개선 공간인 수변완충구역, 또는 지대를 설정하여 관리하는 것이다. 그러나 이러한 수변완충지대 효과 분석 및 설정에 관한 연구는 국내에서 아직 수행되지 않았다. 본 연구의 목적은 수변구역의 자정능력을 높이는 것은 물론 그 밖의 하천 연안에서 비점오염물질의 차단과 처리능력을 증진시키고 수변 생태계의 서식처 보전 및 복원을 위해서 수변완충지대의 수질정화 기술개발과 생물다양성을 창출하는 수변완충지대 조성 기법을 개발하는데 있다. 본 연구에서는 기존 수변완충지의 추가적인 조성과 보완, 시험완충지 생태구조 및 기능 기초조사, 시험완충지 오염부하 저감효과의 실험 및 분석, 수변완충지대 설치 구상 등의 연구를 수행하여 수변완충지대 조성 시 설정 폭을 산정할 수 있게 하였다. 수행 지역은 한강수계 지역으로 남한강 수변인 경기도 양평군 병산리에서 실시하였으며, 잔디와 갈대, 갯버들, 혼합지역, 자연그대로의 상태(대조지역)의 5 구역으로 구분하였고, 거리별, 깊이별 샘플을 채취하여 유입수에 대한 오염물질 제거효율을 도출하고, 이를 이용하여 수변완충지대의 설계 시 필요한 유역의 폭, 면적, 길이 등과 같은 설계인자를 도출할 수 있도록 하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.27-38
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• 1994

In this paper, a simplified model of a hydraulic actuator system for a low-band type active suspension system is derived. To reduce the order of model, time constants of each chamber in hydraulic system are neglected except that of an accumulator. And the dynamics of a spool in the pressure control valve is regarded as a first-order system. The step response and the frequency response of the simplified second-order simulation model exhibit a good agreement with those of the actual system as well as those of the tenth-order simulation model. It is possible to simplify the tenth-order model to the second-order one. The low-band type active suspension model is built up by combining of a quarter car model test rig to testify the validity of the simplified model. The experimental results of suspension characteristics show that the simplified second-order hydraulic actuator model is reasonable to describe the dynamics of the actual hydraulic actuator system for a low-band type active suspension system.

• Advances in Traditional Medicine
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• v.8 no.1
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• pp.17-23
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• 2008

While full recognition of the practical value of Traditional Chinese Medicine is being endorsed, the current stand on the research methodology of this field should be worked out. Since modern medicine has already developed a logical system of research methodology basing on the principles of deduction, any research on any system of medicine need to take reference to what is most popularly used and commonly recommended. The best way to approach research on Chinese Medicine, therefore, would be one that would take full reference to the methodology being used in modern medicine, while at the same time respecting the traditional approach. This would enable traditional medicine to be elevated to the level of general modern recognition. Nevertheless, innate problems in traditional medicine are making its research difficult. The problems lie in difficulties to achieve uniform herb supply, principles of randomization and placebo arrangements, uncertain chemical structures and toxicology etc. A practical approach centered on carefully planned evidence-based clinical trials, with parallel studies on biological activities and herb authentication is being recommended.