• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.3-10
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• 2014

Direct conversion receiver(DCR) gets noticed for integration and cost reduction of wireless communication systems instead of the heterodyne receiver which uses complex filter. But DCR has several factors in performance degradation. One of them is I/Q imbalance phenomenon, that is amplitude and phase mismatch between real and imaginary part of receiver. Accordingly, researches are being carried to improve the I/Q imbalance problem. However, the tendency of the broaden bandwidth of communication systems, low pass filter(LPF) mismatch problem affects severely in I/Q mismatch phenomenon at the DCR. To study this problem, we generated 10MHz broadband signal and shifted it ${\pm}8MHz$ from the center frequency. The signal is affected by LPF mismatch and it appears as frequency selective distortion. Thus, LPF mismatch model is added to I/Q imbalance model which conventionally dealt with amplitude and phase mismatches. In addition, we proposed the compensation method for each factors of mismatch. As the simulation results, the proposed I/Q mismatch compensator resolves the frequency selective distortion which occurred by the existing LPF mismatch.

• ETRI Journal
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• v.30 no.2
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• pp.261-267
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• 2008

In this paper, we propose and demonstrate a cost-effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s-based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super-FEC, carrier-suppressed return-to-zero, and pre-emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line-rate long-haul DWDM links, including $40{\times}40$ Gb/s transmission over KT's standard single-mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q-value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.158-170
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• 2009

In this paper, we propose the new torus network which has the hypercube Q3 as the basic module. The proposed Hyper-torus has the degree 4, and is the network which has the scalability, and the fine diameter. If we compare the class of the torus in the viewpoint of network cost, the hyper-torus with $1.4{\sqrt{N}}$+ 16 is proved to be approximately 65% than the torus with $4{\sqrt{N}}$ and 50% than the honeycomb with $2.45{\sqrt{N}}$. This result means that hyper-torus is better for the class of the existing mesh in the viewpoint of network cost.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.414-422
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• 2011

In this paper, we analyze the standards of the bolts for maintaining the products. The maintainer don't know the detail information of bolts by seeing the shape of bolts when they repair the products. So they waste much time and cost. To solve the these problem, we propose the new systematical discrimination of bolts. To propose the discrimination code, we divide the shapes of the bolts into four classes(head, internal drive, shank and end). User can fine preferentially similar standards by just the shapes of bolts under the this discrimination code. And, User can find the standards of bolts that they want by using the additional information such as measurements. We will reduce the cost and time for the maintaining the products by using the proposed discrimination code.

• Journal of Korean Society for Quality Management
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• v.13 no.2
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• pp.2-7
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• 1985

This paper introduces two approaches of the cost-oriented QC and the process-oriented QC, and compares them on several aspects. The cost-oriented QC tries to assure the specified quality level by sampling inspection within minimum quality cost, while the process-oriented QC aims at realization of target value of quality specification through process adjustment when a product deviates from the target. But the final purpose of both approaches is on quality assurance for markets and consumers. After all, desirability is a question of quality cost. This paper suggests two of cost functions for decision making criterion.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.133-141
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• 2008

In this study, a new method for estimating the undrained shear strength $s_u$ of saturated clays using piezocone penetration test (CPTu) result is proposed. This is to develop more effective CPTu-based $s_u$ estimation method at lower cost with less uncertainty. For this purpose, a marine clay deposit is selected and tested through extensive experimental testing program including both in-situ and fundamental laboratory tests. The proposed method is based on a correlation between the undrained shear strength $s_u$ and the cone resistance $q_t$, without introduction of the total overburden stress into the $s_u-q_t$ correlation. As a result, no additional testing procedure for collecting undisturbed soils samples is required, which can reduce overall testing cost. To verify the proposed method, 4 test sites, which consist of a variety of soil conditions, are selected and used for comparison between measured and predicted undrained shear strength. From comparison, it is seen that predicted values of $s_u$ using the proposed method match well those from measured results.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.3
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• pp.71-84
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• 2009

This paper considers a remanufacturing and purchasing planning problem, in which either used products(or wastes) are remanufactured or remanufactured products(or final products) are purchased to satisfy dynamic demands of remanufactured products over a discrete and finite time horizon. Also, as remanufactured products are purchased more than or equal to a special quantity Q, a discount price policy is applied. The problem assumes that the related cost(remanufacturing and inventory holding costs of used products, and the purchasing and inventory holding costs of remanufactured products) functions are concave and backlogging is not allowed. The objective of this paper is to determine the optimal remanufacturing and purchasing policy that minimizes the total cost to satisfy dynamic demands of remanufactured products. This paper characterizes the properties of the optimal policy and then, based on these properties, presents a dynamic programming algorithm to find the optimal policy. Also, a network-based procedure is proposed for the case of a large quantity of low cost used products. A numerical example is then presented to demonstrate the procedure of the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.17-24
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• 1998

We proposed a novel bondwire inductor buried in plastic package for low cost MMIC and characaterized the electrical perofmrance in a wide frequency range using the full-wave analysis of finite element method(FEM), and then we fabricated and measured the scale-up model in order to prove the characteristics. Th ebondwire inductor has higher quality factor and higher cutoff frequency than the conventional spiral inductor designed n the same area as the bondwire inductor. Since the air-bridge process is not requried for the bondwire inductor, it is very suitable for low cost plastic-packaged MMIC production. The bondwire inductor has the field distribution localized around the bondwire inductor and hence is more compatible to the crosstalk problems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.31
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• pp.59-72
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• 1994

This paper deals with ordering policies of consumable goods which have large demand rates in a multi-level distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N non-identical Regional Distribution Centers(RDCs) which have different demand rates, minimum fillrates, leadtimes, etc. The customer demand on the RDC is stationary poisson and the RDCs demand on the CDC is superposition of Q-stage Erlang distributions. We approximate the RDCs and CDC demand distribution to nomal in order to enhance the efficiency of algorithm. The relevant costs include a fixed ordering cost and inventory holding cost, and backorder cost. The objective is to find a continuous-review ordering policy that minimizes the expected average costs under constraints of minimum fill rates of RDCs and maximum allowable mean delay of CDC. We developed an algorithm for determining the optimal ordering policies of the CDC and the RDCs. We verified and compared the performance of the algorithm through the simulation using the algorithm result as the input parameters.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2031-2034
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• 1999

현재 우리나라에서는 도로망의 급속한 확충에 따라 터널의 수가 급속히 증가하고 있다. 터널은 운전자들이 주야간으로 안전하고 쾌적하게 주행할 수 있도록 설계되어야 한다. 이런 관점에서 터널의 조명설계는 매우 중요하다고 할 수 있으며, 터널의 안전성, 쾌적성, 경제성을 확보하기 위한 여러 가지 복합적인 요소들을 고려한 분석이 필요하다. 이 논문에서는 터널조명에 일반적으로 사용되고 있는 저압나트륨등에 대하여 대안으로 대두되고 있는 형광등에 대한 경제성 측면에서의 비교 방법론 연구를 수행한다. 각각의 등에 대하여 동일 한 터널 노면기준조도를 구현하기 위한 필요 등의 수를 시뮬레이션을 통하여 결정하고, 이를 기반으로 각 터널 조명에 소요되는 Life Cycle Cost를 기본 Model을 통하여 산정하고 비교하는 방법을 제시한다. 이러한 분석은 터널개발 사업의 정책적 결정에 있어 기초 방법과 자료로서 활용될 수 있을 것이다.