• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.202-207
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• 2010

In this paper, a novel voltage-controlled oscillator(VCO) using the open loop multiple split ring resonator(OLMSRR) is presented for improving the phase noise, implemented in 130 nm CMOS technology. Compared with the conventional CMOS LC resonator, the proposed CMOS OLMSRR has the larger coupling coefficient value, which makes a higher Q-factor, and has improved the phase noise of the VCO. The proposed CMOS VCO based OLMSRR has the phase noise of -99.67 dBc/Hz @ 1 MHz in the oscillation frequency. Compared with the VCO using the conventional CMOS LC resonator and the proposed VCO using the CMOS OLMSRR structure has been improved in 7 dB. The prototype 24 GHz CMOS VCO is implemented in 130 nm CMOS and occupies a compact die area of $0.7\;mm{\times}0.9\;mm$.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.134-142
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• 2003

We present an ATM switch architectures based on the multistage interconnection network(MIN) for the efficient multicast traffic control. Many of these applications require multicast connections as well as point-to-point connections. Muiticast connection in which the same message is delivered from a source to arbitrary number of destinations is fundamental in the areas such as teleconferencing, VOD(video on demand), distributed data processing, etc. In designing the multicast ATM switches to support those services, we should consider the fairness(impartiality) and priority control, in addition to the overflow problem, cell processing with large number of copies, and the blocking problem. In particular, the fairness problem which is to distribute the incoming cells to input ports smoothly is occurred when a cell with the large copy number enters upper input port. In this case, the upper input port sends before the lower input port because of the calculating method of running sum, and therefore cell arrived into lower input port Is delayed to next cycle to be sent and transmission delay time becomes longer. In this paper, we propose the cell splitting and group splitting algorithm, and also the fairness scheme on the basis of the nonblocking characteristics for issuing appropriate copy number depending on the number of Input cell in demand. We evaluate the performance of the proposed schemes in terms of the throughput, cell loss rate and cell delay.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.4
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• pp.93-100
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• 2021

The Ethereum shard system for solving the scalability problem of the blockchain has a load balancing issue, which is modeled as a graph partitioning problem. In this paper, we propose an adaptive online weighted graph partitioning algorithm that can negotiate between two utility of the shard system using the game theory's bargaining solution. The bargaining solution is an axiomatic solution that can fairly determine the points of conflict of utility. The proposed algorithm was improved to apply the existing online graph partitioning algorithm to the weighted graph, and load balancing was performed efficiently through the design considering the situation of the sharding system using the extension of Nash bargaining solution, which is extended to apply solution to non-convex feasible set of bargaining problem. As a result of the experiment, it showed up to 37% better performance than typical load balancing algorithm of shard system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4378-4384
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• 2012

In LED chip packaging, die bonding is a very important process which fixes the LED chip on the lead frame to provide enough strength for the next process. This paper focuses on the process optimization of a LED die bonding, which attaches small zener diode chip on PLCC LED package frame, using response surface analysis. Design of experiment (DOE) of 5 factors, 3 levels and 5 responses are considered, and the results are investigated. As the results, optimal conditions those satisfy all response objects can be derived.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.1016-1023
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• 2000

The present work is concerned with three-dimensional finite element analysis of the hollow section extrusion process using a porthole die. The effects of related design parameters are discussed through the finite element simulation for extrusion of a triply-connected rectangular tubular section. For economic computation, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented. In order to obtain the uniform flow at the outlet, design parameters such as the hole size and the hole position are investigated and compared through the numerical analysis. Comparing the velocity distribution with that of the original design, it is concluded that the design modification enables more uniform flow characteristics. The analysis results are then successfully reflected on the industrial porthole die design.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1958-1959
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• 2011

RBFNNs(Radial Basis Function Neural Networks) 모델의 경우 Min-Max, HCM(Hard C-means)클러스터링 그리고 FCM(Fuzzy C-means)클러스터링 중 한가지를 통해 데이터 입자는 로드 규칙을 생성한 후 퍼지 공간을 분할 및 가우시안 함수의 정점을 정의한다. 본 논문은 기존의 방법과는 다르게 Min-Max와 FCM클러스터링을 혼합하여 로드의 규칙을 생성한 후 퍼지 공간을 분할 및 가우시안 함수의 정정을 정의하는 방법으로 사용하고자 한다. PSO최적화 알고리즘을 이용하여 같은조건에서 최적화한 기존의 방법으로 모델링된 RBFNNs와 Min-Max와 FCM 클러스터링을 혼합하여 사용한 방법의 비교를 통하여 어떤 모델의 성능이 더욱 좋은지 비교하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.105-108
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• 1997

To reduce design period, demands for rapid prototyping system is increasing. Among the rapid prototyping system, as a concept modeler, 3D Printer appears before the footlights. In spite of short production time and convenience, 3D Printer causes post processing problem. And that is too slow to adapt to the demand of workshop. In this research, we developed a system for reducing build time and roughness using splitting operation. Also, propose BFS(B-rep For STL) data structure to maintain model data, split STL model and implement Euler Operation for input and output.

• Transactions of Materials Processing
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• v.5 no.1
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• pp.47-54
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• 1996

An improved nonparametric tool description based on successive refined nonparametric patches is proposed and the related criterion for refinement is also discussed. In the proposed scheme any required order of tool surface conformity can be achieved by employing successive refinements according to the suggested criterion. By using the suggested adaptive tool refinement technique based on the nonparametric patch tool description the locally refined nonparametric tool surface with economic memory size and sufficient accuracy as well as with favorable characteristics for contact treatment can be obtained directly from the parametric patch related with commercial CAD system. Computation is carried out for a chosen complex sheet forming example of an actual autobody panel in order to verify the validity and the efficiency of the developed tool surface description.

• Korean Journal of Construction Engineering and Management
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• v.6 no.6 s.28
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• pp.90-97
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• 2005

Poor usage of work-continuity for planning and management is one of the leading causes of decreased productivity in high-rise and complexity construction projects. For efficient finish work, tact scheduling method needs to be implemented according to tact time. But there are the studies about zoning of work area, daily construction information and tact planning and management, there are not the studies about tact time yet. The purpose of this study is to help implementation of tact scheduling by tact time and adjusted work-plan. The main contents of this study are as follow; (1)Tact time has been calculated as coordination of work-plan between a general contractor and specialties. (2)Project-plan can be without delay by tact time calculation method.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.658-664
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• 2006

$\rho$, $\alpha$-dimethyl benzyl alcohol was resolved by the biphasic dynamic kinetic resolution (DKR). Acidic zeolite was used as a racemization catalyst while immobilized enzyme was employed for kinetic resolution. The effects of the process variables including nature of acyl donor, reaction temperature, substrate concentration, ratio of the two catalysts and stirring rate on the conversion and enantiomeric purity of the product were investigated. In DKR of $\rho$, $\alpha$-dimethyl benzyl alcohol, the product of 99% ee was obtained with a maximum yield of 88%. The high performance of the catalyst system was maintained in the condition of higher TON and under repeated use.