• 대한기계학회논문집A
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• 제25권11호
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• pp.1844-1853
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• 2001

In the present investigation, it was attempted to design the rolling pass schedule fur a clean steel of 0.1C-1.5Mn-0.25Si with the objective of the austenite grain refinement. As the method of approach, a coupled mathematical modeling technique was proposed which consists of a recrystallization model and a flow stress modes. The validity of the coupled model was examined through comparison with results of continuous and discontinuous compression tests at various temperatures, strains and strain rates. The coupled model was incorporated with the finite element method to set up a systematic design methodology far the rolling path schedule for austenite grain refinement. Two path schedules were obtained and discussed in the paper with regard to rolling path time, average grain size, grain size deviation in thickness, etc.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.774-780
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• 2016

In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.

• 한국전자파학회논문지
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• 제11권3호
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• pp.410-418
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• 2000

본 논문에서는 27GHz에서 전파환경별 경로손실을 측정하고, 각 수신지점에서 5분간 측정된 경로손실 데이터의 중앙값, 최대값, 최소값을 선형회귀 모델로 모델링하고 분석하였다. 측정 결과를 살펴볼 때, 밀리미터파 대역 가시경로의 경우에도 도심이나 부심 환경에서는 추가의 경로손실을 고려해야 할 것으로 생각된다.

• Journal of Communications and Networks
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• 제5권3호
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• pp.230-239
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• 2003

In this paper, we propose a framework to study how to route packets efficiently in multipath communication networks. Two traffic congestion control techniques, namely, flow assignment and packet scheduling, have been investigated. The flow assignment mechanism defines an optimal splitting of data traffic on multiple disjoint paths. The resequencing delay and the usage of the resequencing buffer can be reduced significantly by properly scheduling the sending order of all packets, say, according to their expected arrival times at the destination. To illustrate our model, and without loss of generality, Gaussian distributed end-to-end path delays are used. Our analytical results show that the techniques are very effective in reducing the average end-to-end path delay, the average packet resequencing delay, and the average resequencing buffer occupancy for various path configurations. These promising results can form a basis for designing future adaptive multipath protocols.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.515-515
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• 2000

The performance of dynamic path following of a wheeled mobile robot with nonholonomic constraints has some drawbacks such as the influence of the initial state. The drawbacks can be overcome by the temporary path generator and modified output. But with the previous input-output linearization method using them, it is difficult to tune the gains, and if there are some modeling errors, the low gain can make the system unstable. And if a high gain is used to overcome the model uncertainties, the control inputs are apt to be large so the system can be unstable. In this paper. an H$_{\infty}$ controller is designed to guarantee robustness to model parameter uncertainties and to consider the magnitude of control inputs. And the solution to Hamilton Jacobi (HJ) inequality, which is essential to H$_{\infty}$ control design, is obtained by nonlinear matrix inequality (NLMI).

• 한국전자파학회논문지
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• 제13권7호
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• pp.726-731
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• 2002

이 논문은 이동전화 기지국 설치를 위한 전파 환경 분석을 목적으로 하고 있다. 대상지역의 최대거리는 150 km, 면적은 6000 $\textrm{km}^2$에 이르며, 총 5개의 기지국에서 이동전화 서비스를 할 수 있도록 하기 위하여 필드 측정을 하였다. 이렇게 측정한 전파환경을 하타(Hata)모델과 오쿠무라(Okumura)모델로 근사시켜 경로손실 예측모델을 선정하였다. 필드테스트 분석 결과, 측정된 지역의 전파환경 경로손실은 농촌지역과 도시근교지역의 중간 지역의 하타(Hata) 모델로 근사할 수 있다는 것을 알 수 있었다.

• 대한기계학회논문집
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• 제18권1호
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• pp.53-64
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• 1994

Rouge cutting process takes the major portion of machining operation using NC milling machine. Especially, most of the machining time is spent in this process when molds are machined. Therefore, an efficient algorithm for generating the tool path for rough cutting is suggested in this paper. The first step of the procedure is getting the volume to be machined by applying the Boolean operation on the finished model and the workpiece which have been modeling system. Basic principle of determining machining procedure is that a large tool should be used at the portion of the simple shape while a small tool should be used at the complex portion. This principle is realized by representing the volume to be machined by an octree, which is basically a set of hexahedrons, and matching the proper tools with the given octants. When the tools are matched with the octants, the tool path can be derived at the same time.

• 한국신뢰성학회지:신뢰성응용연구
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• 제8권4호
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• pp.181-192
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• 2008

In this paper, we proposed effective algorithm that do Availability of communication network account using total probability formula. Use path tracing method about PSTN linked with MSC in WCDMA considering occasion that do not consider mobility of terminal and Availability did account. First, express minimum path series gathering by structure function after network that do modeling by stochastic graph for communication network saves all minimal path sets between particular two abutments and we gain Availability value in angular variable after express structure function by Boolean operation form and Availability between two abutments did account.

• Asia Marketing Journal
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• 제18권4호
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• pp.27-49
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• 2017

The two competing underlying mechanisms of anchoring, anchoring-and-adjustment and selective accessibility, have very different managerial implications for the effect of price as an anchor on willingness-to-pay (WTP). To clarify their relative roles in inducing the anchoring effect, path analysis modeling in which two paths are included in a single model was utilized. The first path proceeds directly from anchor price to WTP, representing anchor-and-adjustment. The second path, representing selective accessibility, includes a mediator formed by various explanatory variables of WTP. The results consistently show that only the direct path, anchoring-and-adjustment, is significant. The results also show that the level of available product information has no significant moderation effect on both of the paths, which implies the robustness of the result with respect to information level.

• 한국CDE학회논문집
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• 제12권1호
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• pp.39-49
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• 2007

Recently three-dimensional (3-D) die design and production process has been widely introduced into the tooling shops of automotive manufacturers to reduce time-to-production of brand-new automobiles. 3-D solid models created in CAD systems are used not only for various simulations for design verification, but also for NC tool path generation to machine dies and their Styrofoam patterns. However, a lot of time and cost will be required to build solid models for dies if designers use only the generalized modeling capabilities of commercial 3-D CAD systems. To solve this problem, it is necessary to customize 3-D CAD system for the specific die design and manufacturing process. This paper describes a dedicated 3-D CAD system based on Unigraphics for die design for automotive body panels. The system provides not only 3-D design capabilities, but also standard part libraries, to enhance design productivity. The design process modeling technology has been introduced to facilitate redesign of the die for the modified panel. By introducing this system, dies can be designed more rapidly in the 3-D space, and their solid data can be directly transferred to CAM tools for NC tool path generation and simulation tools for virtual manufacturing.