Analytical Transfer Functions Relating Power and Ground Voltage Fluctuations to Jitter at a Single-Ended Full-Swing Buffer

Chulsoon Hwang,Jingook Kim,Achkir, B.,Jun Fan IEEE 2013 IEEE transactions on components, packaging, and ma Vol.3 No.1

<P>The transfer functions relating supply voltage fluctuations to jitter are analytically derived in closed form expressions for a single-ended buffer. The analytic transfer functions are derived from a linear differential equation obtained from asymptotic linear inverter I-V curves. The transfer functions are validated by comparison with HSPICE simulations. The estimated jitter is compared with the simulated jitter using eye diagrams with single-frequency and multitone supply voltage fluctuations.</P>

Revision Total Hip Arthroplasty after Ceramic Bearing Fractures in Patients Under 60-years Old; Mid-term Results

( Chulsoon Im ),( Kyung-jae Lee ),( Byung-woo Min ),( Ki-cheor Bae ),( Si-wook Lee ),( Hyuk-joon Sohn ) 대한고관절학회 2018 Hip and Pelvis Vol.30 No.3

Purpose: Although advances in technology have reduced the risk of ceramic implant fractures in total hip arthroplasty, these injuries do occur and their treatment remains challenging. There is a lack of studies reporting on the effectiveness of ceramic components in revision hip arthroplasty after ceramic bearing fracture. The aim of this study is to evaluate clinical and radiologic outcomes of revision surgery with ceramic-on-ceramic components after ceramic bearing fractures in young (i.e., under 60 years old) and active patients. Materials and Methods: Eight patients who, from May 2004 to November 2011, underwent ceramic-onceramic revision surgery following a ceramic component fracture and had more than 6 years follow up were enrolled in this study. All eight patients were male with mean ages at first and revision surgeries of 39 years (range, 31-50 years) and 43.8 years (range, 33-60 years), respectively. There were 6 and 2 cases of ceramic liner and ceramic head fractures, respectively. The average time from the first operation to revision surgery was 54.3 months (range, 9-120 months), and the average follow up period was 9.7 years (range, 6-13.3 years). Results: At the last follow up, all patients showed improvement in Harris hip score and pain relief and there were no cases of loosening or osteolysis. Conclusion: Revision total hip arthroplasty using ceramic-on-ceramic components after ceramic component fracture is a feasible and appropriate surgical option in young and active patients.

Modeling of an On-Chip Power/Ground Meshed Plane Using Frequency Dependent Parameters

Chulsoon Hwang,Kiyeong Kim,Jun So Pak,Joungho Kim 한국전자파학회JEES 2011 Journal of Electromagnetic Engineering and Science Vol.11 No.3

This paper proposes a new modeling method for estimating the impedance of an on-chip power/ground meshed plane. Frequency dependent R, L, and C parameters are extracted based on the proposed method so that the model can be applied from DC to high frequencies. The meshed plane model is composed of two parts: coplanar multi strip (CMS) and conductor-backed CMS. The conformal mapping technique and the scaled conductivity concept are used for accurate modeling of the CMS. The developed microstrip approach is applied to model the conductor-backed CMS. The proposed modeling method has been successfully verified by comparing the impedance of RLC circuit based on extracted parameters and the simulated impedance using a 3D-field solver.

A Wideband and Compact Partial Electromagnetic Bandgap Structure With a Narrow Via Pitch for a Signal Via Shield

Chulsoon Hwang,Jaemin Kim,Eakhwan Song,Yujeong Shim,Joungho Kim IEEE 2011 IEEE transactions on electromagnetic compatibility Vol.53 No.1

<P>A wideband and compact partial electromagnetic bandgap (PEBG) structure and a corresponding stopband-estimation model are proposed for the suppression of simultaneous switching noise (SSN) coupling in a multilayer printed circuit board. The proposed PEBG structure achieves a wide stopband with a compact size by adopting a geometric arrangement of patches that allows for a periodic narrow via pitch (NVP). In addition, the lumped capacitance model of the previously reported effective phase constant equation is replaced with the resonant cavity model to obtain the precise impedance of the patch in high frequency. Finally, it was successfully verified that, by applying the NVP-PEBG structure, wideband suppression of SSN coupling to the signal via is achieved with a bandwidth of 11.2 GHz below -40 dB. The proposed estimation model was validated through experimental measurements.</P>

Predictive Maintenance in Injection Molding Process

ChulSoon Park,DugHee Moon 한국산업경영시스템학회 2014 한국산업경영시스템학회 학술대회 Vol.2014 No.춘계

In this research, we are developing a predictive maintenance model of the injection molding machines based on the prediction of trend of injection molding parameters. At first, we developed an interface method to directly monitor the real-time injection molding parameter data from injection molding machine controller. Second, we identified the principal injection parameters which mainly affect the quality of injection molding products and need to be monitored for maintenance. Third, based on the time series analysis, we developed the prediction models of the principal injection molding parameters, which are identified by previous statistical model to forecast its future patterns/trends and schedule its maintenance point in time. We adopted Nelson’s rules to identify abnormal patterns in predicted data. Finally, we used FTA (fault tree analysis) to relate the injection molding parameters to the parts of the injection molding machine, find out the equipment or parts to be corrected.

Logistics Allocation and Monitoring System based on Map and GPS Information

Chulsoon Park,Larsson Bajracharya 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.4

In the field of optimization, many studies have been performed on various types of Vehicle Routing Problem (VRP) for a long time. A variety of models have been derived to extend the basic VRP model, to consider multiple truck terminal, multiple pickup and delivery, and time windows characteristics. A lot of research has been performed to find better solutions in a reasonable time for these models with heuristic approaches. In this paper, by considering realtime traffic characteristics in Map Navigation environment, we proposed a method to manage realistic optimal path allocation for the logistics trucks and cargoes, which are dispersed, in order to realize the realistic cargo mixing allowance and time constraint enforcement which were required as the most important points for an online logistics brokerage service company. Then we developed a prototype system that can support above functionality together with delivery status monitoring on Map Navigation environment. First, through Map Navigation system, we derived information such as navigation-based travel time required for logistics allocation scheduling based on multiple terminal multiple pickup and delivery models with time constraints. Especially, the travel time can be actually obtained by using the Map Navigation system by reflecting the road situation and traffic. Second, we made a mathematical model for optimal path allocation using the derived information, and solved it using an optimization solver. Third, we constructed the prototype system to provide the proposed method together with realtime logistics monitoring by arranging the allocation results in the Map Navigation environment.

An On-Chip Electromagnetic Bandgap Structure using an On-Chip Inductor and a MOS Capacitor

Chulsoon Hwang,Yujeong Shim,Kyoungchoul Koo,Myunghoi Kim,Jun So Pak,Joungho Kim IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.8

<P>An on-chip electromagnetic bandgap (EBG) structure using a CMOS process is proposed. The proposed structure is the first EBG structure devised to suppress simultaneous switching noise coupling in an on-chip power distribution network (PDN). The on-chip EBG structure utilizes an on-chip inductor and a MOS capacitor to generate a stopband with a range of several GHz in an extremely small size; thus, the EBG structure can be embedded in on-chip PDNs. The proposed on-chip EBG structure was fabricated using a MagnaChip 0.18 μm CMOS process, and we successfully verified a 9.24 GHz stopband, from 1.26 to 10.5 GHz, with an isolation level of 50 dB.</P>

Measuring a Value of Contract Flexibility in the Third-Party Warehousing

Chulsoon Park,Bowon Kim 한국경영과학회 2009 Management Science and Financial Engineering Vol.15 No.1

This paper considers the value of warehousing contract under probabilistic demands. We consider a supply chain consisting of a supplier, a retailer and its third-party warehousing partner who provides the warehousing service to the retailer through an outsourcing contract. A typical contract is specified by initial space commitment and modification schedule. The retailer decides the order quantity for the supplier and space commitment for the outsourcing contract. Since there is close relationship between order quantity and space commitment to minimize the total cost including ordering cost, inventory carrying cost, shortage cost, and warehousing cost, we develop an analytical model under probabilistic demands, where the retailer can determine the optimal order size and space commitment level jointly. We found the closed-form optimum for a single-period case and the optimal conditions for a two-period case. To evaluate the value of contract flexibility for the twoperiod case, we compared the total cost under two policies; one with modification, under which the base commitment can be changed at the start of each period and the other without modification. From results of our numerical analysis, we showed that the modification policy is more cost-effective as the variability of demand increases.

개방형 혁신 네트워크의 동태적 모형

박철순(Chulsoon Park) 한국경영과학회 2015 한국경영과학회지 Vol.40 No.1

Literatures on open innovation have two major limitations. First, either on a firm level or on an industry level did they analyze the open innovation issues. The results of a firm’s innovation can be diffused through the whole network and the firm can learn back from the network knowledge. Prior literatures did not consider the feedback loop among firms and network in which the firms are involved. Second, most open innovation research had a static perspective on firm’s innovation performance. Since the diffusion, spill-over and learning among network members are involved over time, the open innovation is intrinsically dynamic. From the dynamic perspective, we can appreciate the fundamental attributes of the open innovation network which involves diverse firms, research institutes, and universities. In order to overcome the limitations, we suggest a dynamic model for open innovation network. We build an agent-based model which consists of heterogeneous firms. The firms are connected through a scale-free network which is formed by preferential attachment. Through the diverse scenario of simulation, we collect massive data on the firm level and analyze them both on firm and industry level. From the analysis, we found that, on industry level, the overall performance of open innovation increases as the internal research capability, absorptive capacity, and learning curve coefficient increase. Noticeably, as the deprecation rate of knowledge increases, the variability of knowledge increases. From the firm level analysis, we found that the industry-level variables had a significant effect on the firm’s innovation performance lasting through all the time, whereas the firm-level variables had only on the early phase of innovation.

On the w-spaces

Han, Chulsoon 제주대학교 1980 논문집 Vol.12 No.-

도입과정에서 주어진 명제의 ??-space의 정의를 가지고 ??-space가 될 수 있는 공간, 그리고 어떤 조건을 주어서 이의 거리화 문제를 증명하였다. 그러나 어떤 조건을 가진 ??-space는 거리화가 될 수 있는지의 미해결문제를 결론에서 제시함으로 이 논문을 끝내고자 한다. Given a definition of the ??-space, we have proved what a ??-space is, and a metrization of the w-space with conditions. Furthermore, we will have an open problem: Is a collectionwise normal w-space with a ??-diagonal metrizable?