• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.209-216
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• 1994

Rock mass classifications have played an indispensable role in underground construction for several decades. An important issue in rock mass classifications is the selection of the parameters of greatest significance. There appears to be no single parameter that can fully describe a jointed rock mass for underground construction design. In this paper. We find some problems shen applied rock mass classification for underground construction in domestic, analyze the most significant parameters and parameters correlation influencing the behavior of a rock mass, and suggest the Simplied Rock Mass Rating system based on RMR method for effective underground supports.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
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• pp.47-51
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• 2001

According as the controlled plants become more complex and large-scaled, the development of more intelligent control schemes is required in the control field. A fuzzy logic control (FLC) is one of proper schemes for this tendency. Recently, fuzzy control has been applied successfully to many industrial applications due to a number of advantages. But it still has some disadvantages. The conventional FLC has many tuning parameters: membership functions, scaling factors, and so forth. In order to improve this problem, a single-input fuzzy logic control (SFIC) which greatly simplifies the design process of the conventional FLC was proposed. Many research has also been proposed to develop the stability analysis of the FLC. In this paper we analyze the absolute stability of the SFLC. We first expand a nonlinear controlled plant into a Taylor series about a nominal operating point. And a fuzzy control system is transformed into a Lure system with nonlinearities. We also prove that the closed-loop system with the SFLC satisfies the sector condition globally.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.163-167
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• 2000

This paper presents the digital control of single-phase power factor correction(PFC) converter which has the variable gain according to the condition of inner control loop error. Generally the gain of inner current control loop in single-stage PFC converter has a constant magnitude. This has a bad influence on the power factor because current loop doesn't operate smoothly in the condition that input voltage is low In particular a digital controller has more time delay than an analog controller and degrades This drops the phase margin of the total digital PFC system,. It causes the problem that the gain of current control loop isn't increased enough. In addition the oscillation happens in the peak value of the input voltage open loop PFC system gain changes according to ac input voltage. These aspects make the design of the digital PFC controller difficult The digital PFC controller presented in this paper has a variable gain of current control loop according to input voltage. The 1kW converter was used to verify the efficiency of the digital PFC controller.

• 대한의용생체공학회:의공학회지
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• 제39권3호
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• pp.134-139
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• 2018

One of the most common problems with pedicle screw system is pullout of the screw. This study was performed to evaluate the pullout strength and driving torque of newly designed pedicle screws. The design of three type screws were standard pedicle screw, which had single lead threaded and single pitched design (Type A), single pitched and dual lead threaded pedicle screw (Type B), dual pitched and dual lead threaded pedicle screw (Type C), respectively. The tests were performed in accordance with the ASTM standards using polyurethane (PU) foam blocks. There was no significant difference in pullout strength among three types of screw. Type B and Type C exhibited higher insertion torque and removal torque than Type A, respectively (p<0.05). Pedicle screws newly developed with dual pitched and dual lead threaded design showed higher driving torque without decrease in pullout strength compared to the standard pedicle screw and could be inserted more rapidly with the same number of revolutions.

• 한국통신학회논문지
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• 제39A권10호
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• pp.579-584
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• 2014

본 논문에서는 패치형 ESPAR(Electronically Steerable Parasitic Array Radiator) 안테나를 이용한 빔 공간 MIMO(beamsapce mulitple input multiple output) 시스템을 제안한다. 기존의 모노폴 ESPAR 안테나의 경우 단일 RF 체인을 갖기 때문에 하드웨어의 비용과 RF회로의 전력 소모를 절감할 수 있는 장점을 가진다. 하지만 공간적 제약이 큰 휴대용 이동기기에 적용하기 문제점이 있다. 따라서 부피를 간소화 시키는 방법으로써 패치형 ESPAR 안테나를 설계하고 단일 RF 체인으로 MIMO 기술이 가능한 빔 공간 MIMO 시스템에서의 성능을 분석한다. 본 논문에서 설계한 패치형 ESPAR 안테나를 통해 빔패턴이 ${\pm}15$도의 앙각의 변화를 가지는 것을 확인하였고, 또한 이 ESPAR 안테나를 사용하여 빔 공간 MIMO 시스템을 구현하고 이 시스템의 BER 성능을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.751-754
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• 1998

This research aims at developing a single chip multiprocessor for high-performance computer system. Our design approach is to design a relatively small and simple processor unit and to integrate multiple copies of the unit in an efficient way. The proposed multiprocessor is composed of four CPUs and one graphic coprocessor. The four CPUs share the graphic coprocessor and each CPU implements the 64-bit SPARC-V9 instruction set architecture. This paper gives an overview of the proposed microarchitecture and discusses the considerations made in the course of the design.

• 전기학회논문지P
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• 제59권1호
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• 대한치과기공학회지
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• 제39권1호
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• pp.35-42
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• 2017

Purpose: The purpose of this paper was to evaluate the occurrence of errors regarding adaptation by conducting a three-dimensional assessment comparing the bridge type dental restoration after the cutting process, which has multiple abutments, with a single type dental restoration. Methods: By using ten identical files obtained by scanning the master model, thirty designs were created consisting of ten maxillary right first premolars and ten maxillary right first molars with single crown abutments, along with ten bridge designs with the identical abutment. A 5-axis milling machine was used to produce the design file. The produced denture prostheses were scanned using a silicone replica for a STL file. An evaluation was conducted using 3D analysis software on the master model and each of the thirty data files. Results: The RMS value of the pre-molar (14) was $38.4{\pm}4{\mu}m$ for single and $54.7{\pm}6{\mu}m$ for bridge abutment; therefore, a statistically significant difference was observed for single and bridge designs although both shared the same abutment form (P<.05). Also, the RMS value of the molar (16) was $47.6{\pm}2{\mu}m$ and $56.6{\pm}5{\mu}m$ for the single and bridge designs, respectively, thereby presenting a statistically significant difference (P<.05). Conclusion: As a result, dental prosthesis fabricated using the single method presented better internal adaptation outcomes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.483-483
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• 2000

The Fuzzy Preview Control (FPC) design methodology using I-PD Preview Control (IPC) and Optimal Preview Control (OPC)[6] are discussed in this paper. First we show a new fuzzy controller with single input single output, and build a relationship between it and the I-PD Control proposed by Kitamari, as well as Optimal Control with some specific equations. We also give the stability analysis with Lyapunov theorem. On this way, we can design a Fuzzy I-PD Controller (FIC) very easier and more effective. Then, preview control element design methodology of FCP was given according to IPC and OPC. Third, to make the system more rapidly and more little overshooting, two factors are given to adjust the controller's properties. At last, the performance of FPC is revealed via computer simulation using a nonlinear plant.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.257-259
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• 2008

Acceleration time history (ATH) used in the seismic analysis should envelop a target power spectral density (PSD) function in addition to the design response spectrum in order to have sufficient energy at each frequency for the purpose of ensuring adequate load. Even though design regulations require the ATH used in seismic analysis to meet a target PSD function, the reason that ATHs meet to a target PSD function is not described. Thus, artificial ATHs for high PSD function and artificial ATHs for low PSD function are generated. And then elastic and inelastic single-degree-of-freedom (SDOF) systems are loaded with these artificial time histories as the earthquake load. As a result, linear response and inelastic response of SDOF systems are affected by PSD function.