• 한국정밀공학회지
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• 제13권8호
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• pp.139-145
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• 1996

Tapping is one of the most widely used machining operations. There are several methodes of producing external screw threads, e.g. turning, milling with single or multiple cutter, rolling, and grinding, but the methods available for cutting enternal threads are less numerous, and for threads in small holes, tapping is employed almost exclusively. In this study, the tap with the various geometry has been developed in order to tap special workmaterial at considerably higher cutting speed than that of the conventional HSS tap. The experimental tests are run with various cutting speed by using a piezo type tool dynamometer to measure tapping torque. Tapping torque is affected by the design of the tap, which seems to be due to internal friction and shearing of the metal. It is clarified that the process of chip formation strongly depends on rake angle, relief angle, angle of twist.

• Journal of Forest and Environmental Science
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• 제27권3호
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• pp.135-141
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• 2011

The present study was carried out from September 2007 to February 2008 in Umfakarin natural forest reserve, South Kordofan, Sudan. The objective was to analyze the effect of different management strategies on yield of gum talha from Acacia seyal. A total of 493 single target trees were selected, based on their diameters, and assigned to tapping treatments in three different stand densities (making a total of nine treatments per stand density). The treatments are as follows: tapping date with three levels (first of October, 15 October and first of November) and two levels of local tapping tools (sonki, and makmak). Untapped trees were used as control. The first picking of gum was started fifteen days after tapping while the subsequent pickings were done in intervals of fifteen days. Yield per tree throughout the season was obtained by summing up the gum yield from all pickings. Yield throughout the season (from first to the last picking) were analyzed. General linear model (GLM) was used to test the effect of different tapping treatments on the yield of gum talha. Post hoc test after analysis of variance (ANOVA) based on Scheffe test was performed to examine the differences in gum yield as a result of different management strategies. The results showed that tapping has a significant influence on gum yield. Analysis of pick-to-pick yield indicated that only three treatments in dense stand density showed a decreasing pattern while the rest of treatments either have constant or unclear patterns. The results of the present study were based on a single season data and that may underscore the real effect of Acacia seyal stands' management strategies on gum talha yield. Conducting gum yield experiments in permanent trial plots are highly recommended in order to analyze gum yield of seasonal time series.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.120-123
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• 2003

To investigate the characteristics of the single dendrimer molecule, we attempt to measure morphology and electrical properties of the self-assembled dendrimer on Au (111)substrate with SPM(scanning probe microscopy). The same self-assembly procedure was used for two different concentrations, $10{\mu}mol/ml$ and $100{\mu}mol/ml$. The case of lower concentration, we can measure the diameter and the height of the single molecule with the tapping mode AFM image. The imaged single molecules were dome shaped and the average diameter and height were 15.6 nm, 1.2 nm respectively. From these sizes, we can calculate the volume of the single molecule. The volume of the single molecule was estimated about $116nm^3$. However, that of higher concentration, it is difficult to obtain obvious image of the single molecule. To add to, I-V characteristics were investigated using STM, on which the phenomenon of negative differential resistance (NDR)was observed between 0.14 V and 0.24 V reproductively.

• 한국컴퓨터정보학회논문지
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• 제17권3호
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• pp.113-120
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• 2012

기존의 IP 망을 이용하여 음성 데이터 서비스를 제공하는 VoIP는 최근 많은 관심을 받고 있다. VoIP 서비스는 다양한 보안 취약성을 포함한다. VoIP 서비스의 주요 공격 유형으로는 도 감청, DoS 공격, 스팸, 서비스 오용 공격 등을 들 수 있다. 이 중에서 도 감청으로 인한 기밀 정보의 유출은 매우 중요한 문제로 다루어지고 있다. VoIP 미디어 정보에 대한 도 감청 방지를 위해 SRTP나 ZRTP와 같은 암호화 기법이 주로 사용되고 있다. 일반적으로 VoIP 서비스는 단일 사설망 내에서의 운용과 서로 다른 사설망간의 운용으로 구분할 수 있는데, SRTP나 ZRTP는 단일 사설망 내에서의 통신 시에는 VoIP 미디어 정보를 암호화 한다. 그러나 두 가지 방법 모두 서로 다른 사설망간의 통신 시에는 암호화를 수행하지 못하는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 본 논문에서는 기존의 SRTP 프로토콜의 일부를 수정하여 서로 다른 사설망간의 통신 시에도 VoIP 미디어 정보에 대한 암호화를 수행할 수 있는 암호화 기법을 제안한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.192-195
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• 2003

There has been increasing interest in the applications of synthesized molecules of nanometer scale in recent years due to their potential utilization in various fields such as biology, optoelectronics and molecular electronics. In this study, the terpyridine-platinum (II) complex on the periphery of the dendritic carbosilane has been prepared from the reaction of Pt(COD)Cl2 and the 4'-functionalized-(2,2':6',2"-terpyridine) on dendrimers. The self-assembly process was carried out to obtain indivially dispersed dendrimer on Au (111) substrate. It was found that STM was unsuitable to obtain a obvious image of dendrimers. Tapping-mode atomic force microscopy(AFM) has been used to investigate the shape and size of dendrimers individually dispersed on Au (111)substrate. As a result, the imaged single dendrimer show that dendrimer is dome shaped and its size can be measured by tapping-mode AFM.

• Steel and Composite Structures
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• 제42권3호
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• pp.315-323
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• 2022

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

• 인터넷정보학회논문지
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• 제16권1호
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• pp.9-20
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• 2015

현대의 사회는 Single tapping, 단방향 통신, 통합 아이디 등 빠름, 간편함, 편리함을 위해 최대한 사용자의 행동 패턴을 줄이고 소모시간이 적게 걸리는 기술이 우선시 되고 있다. 스마트 웰렛 시장과 마찬가지로 사용자의 편의성, 신속성, 간편성을 적용하려는 분야는 통합 아이디 시장이다. 일반적으로 사용자들이 잊어버리기 쉬운 ID와 패스워드를 통합 관리하기 위한 시스템으로서 다수의 ID와 패스워드를 보유하고 있는 사용자가 보유한 다수의 정보를 시스템에 등록하여 한 번의 로그인에 의해 다수의 서비스를 받을 수 있는 기술이다. 하지만 OpenID 시대의 도래에도 다수의 서비스들에서 해당 기술이 적용되지 않는 이유가 각 사업자의 사이트에 일일이 가입해야 하는 등 서로의 이익을 위해 기술 적용을 꺼리는 경우가 많다. 또한, 다수의 포인트 사업자에 가입이 되어 있을 경우, 어떤 포인트의 적립이나 할인이 사용자 본인에게 더 유리한지 한눈에 확인할 수 없기 때문에 스스로 포인트 카드에 맞는 유리함을 계산해야하는 어려움이 있다. 따라서 본 논문은 사용자의 편의성을 위하여 단하나의 ID로 여러 가입된 사이트 및 카드 포인트 적립, 결제와 같은 서비스를 이용할 수 있도록 안전한 통신 아이디어를 제안한다. 또한, 통합 ID를 통하여 가맹점의 혜택 카드를 일일이 찾는 수고를 줄여 보다 간편하고 효율적인 적립이나 할인을 제공할 수 있는 시스템을 제안한다.

• Journal of the Korean Wood Science and Technology
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• 제49권1호
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• pp.93-102
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• 2021

In this article, withdrawal resistances of axially loaded self-tapping screws on wood products made by Korean Larch were predicted with existing estimation equation, and compared with experimental test data. The research was required because no design methodology for the withdrawal resistance of self-tapping screw is present in Korean building code (KBC). First, the withdrawal resistance of wood screw was predicted to use the withdrawal design value estimation equation in National Design Specification for Wood Construction (NDS). Second, three types of wood products, solid wood, cross-laminated timber (CLT) and plywood, were utilized for withdrawal test. For decades, various engineered wood products have been developed, especially cross-laminated timber (CLT) and hybrid timber composites such as timber composites of solid wood and plywood. Therefore, CLT and plywood were also investigated in this study as well as solid wood. Finally, the predicted values were compared with experimentally tested values. As the results, the tested values of solid wood and CLT were higher than the predicted values. In contrast, it is inaccurate to predict withdrawal resistance of plywood since prediction was higher than tested values.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.111-111
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• 2001

목적： To evaluate the feasibility of the event-related functional MR study using power grip studying the hand motor system 대상 및 방법： Event-related functional MRI was performed on a 1.5T MR unit in seven norm volunteers (man=7, right-handedness=2, left-handedness=5, mean age： 25 years). A single-shot GRE-EPI sequence (TR/TE/flip angle： 1000ms/40ms/90, FOV = 240 mm matrix= 64$\times$64, slice thickness/gap = 5mm/0mm, 7 true axial slices) was used for functiona MR images. A flow-sensitive conventional gradient echo sequence (TR/TE/flip angl 50ms/4ms/60) was used for high-resolution anatomical images. To minimize the gross hea motion, neck-holders (MJ-200, USA) were used. A series of MR images were obtained in axial planes covering motor areas. To exclude motion-corrupted images, all MR images wer surveyed in a movie procedure and evaluated using the estimation of center of mass of ima signal intensities. Power grip task consisted of the powerful grip of all right fingers and hand movement ta used very fast right finger tapping at a speed of 3 per 1 second. All tasks were visual-guid by LCD projector (SHARP, Japan). Two tasks consisted of 134 phases including 7 activatio and 8 rest periods. Active stimulations were performed during 2 seconds and rest period were 15 seconds and total scan time per one task was 2 min 14 sec. Statistical maps we obtained using cross-correlation method. Reference vector was time-shifted by 4 seconds an Gaussian convolution with a FWHM of 4 seconds was applied to it. The threshold in p val for the activation sites was set to be 0.001. All mapping procedures were peformed usin homemade program an IDL (Research Systems Inc., USA) platform. We evaluated the activation patterns of the motor system of power grip compared to hand movement in t event-related functional MRI.

• 대한통합의학회지
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• 제3권2호
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• pp.63-72
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• 2015

Purpose: The purpose of this study was to investigate the foot pressure of subjects with hallux valgus following conservative management. Methods: The subjects (20 females) were divided into 2 groups; Hallux valgus group (10) and Control group (10) who could evaluate questionnaire & weight bearing X-ray. All the participants were evaluated distribution of foot pressure by Zebris FDM-S system with conservative management (taping therapy and hallux valgus device) during single-limb stance. Results: The Hallux valgus group (HVG) was significantly different than Control group (CG) in hallux valgus angle(p<0.05). The Hallux valgus group with Foot Device (HVG-FD), Hallux valgus group with Taping (HVG-Tp) and Hallux valgus group with Foot device and Taping (HVG-FD&Tp) was not significantly different than CG in hallux valgus angle (p<0.05). The HVG was not significantly different than CG in forefoot (p1, p2, p3), significantly different than CG in rearfoot (p7) about foot pressure during single-limb stance (p<0.05). The HVG-FO and HVG-FO and TP was significantly different than HVG in forefoot (p1, p2, p3), on significantly different than HVG in rearfoot (p7) about foot pressure during single-limb stance (p<0.05). There was significantly correlation HVG-FO and HVG-FO & TP in forefoot (p1, p2, p3) was negative correlation (p<0.05) and in rearfoot (p7) was positive correlation (p<0.05). Conclusion: This study showed that hallux valgus were effected hallux valgus angle and foot pressure by various treatment methods during single-limb stance. Further study is needed to measure various age and work with hallux valgus for clinical application.