• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.660-669
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• 2008

This paper presents a new carrier based pulse-width modulation (PWM) method for matrix converters. By using the concept of average over one switching period, the modulation algorithm and the required equations are derived to synthesize the desired output voltage and to achieve the controlled input power factor. The proposed method uses a continuous carrier and the predetermined duty ratio signals to directly generate the gating signals and, thus, is referred to as "direct duty ratio PWM (DDPWM)". The feasibility and validity of the proposed method were verified by simulation and experiment.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.636-638
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• 2000

제어 독립성(Control Independence)은 슈퍼스칼라 프로세서에서 명령어 수준 병렬성(Instruction-Level Parallelism)을 향상시키기 위한 중요한 요소로 작용하고 있다. 분기 예상기법(Branch Prediction Mechanism)에서 잘못 예상될 경우에는 예상한 분기 방향의 명령어들을 제거하고 올바른 분기 방향의 명령어들을 다시 반입하여 수행해야 한다. 본 논문에서는 컴파일 시 프로파일링을 통한 정적인 방법과 프로그램상의 제어 흐름을 통해 동적으로 제어 독립적인 명령어를 탐지함으로써 분기 명령어의 잘못된 예상으로 인해 제거되는 명령어를 효과적으로 감소시켜 프로세서의 성능을 향상시키는 메커니즘을 제안한다. SPECint95 벤치마크 프로그램에 대해 기존의 방법과 본 논문에서 제안한 방법 사이의 사이클 당 수행된 명령어 수를 분석한 결과, 4-width 프로세서에서 4%~6%, 8-width 프로세서에서 11%~18%, 16-width 프로세서에서 15%~17%의 성능 향상을 보이고 있다.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.670-674
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• 2016

The control performance of hybrid PWM inverter using a phase current measurement is presented in this paper. The hybrid PWM technique consists of space vector pulse width modulation (SVPWM) and six-step voltage control operation. The SVPWM is performed to reduce the harmonic components in the low speed region, and the six-step modulation is applied to increase the maximum speed of the IPMSM in the high speed region. Therefore, it is possible to obtain a great performance in both the low speed range and high speed range. However, the six-step modulation cannot be completely implemented, since the inverter that includes the lag-shunt sensing method has an immeasurable current region. In this paper, a quasi-six-step modulation using a modified voltage vector is proposed. The validity and usefulness of the proposed PWM technique is verified by MATLAB/Simulink and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05c
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• pp.31-35
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• 2004

We propose driving method of Ultraviolet sensor for fire alarms using pulse width modulation that used to fire detector with sensor of private-use detectable light energy as ultraviolet in energy of electromagnetic-wave type radiate from flame, when combustible burn with contain carbon,. Ultraviolet sensor is UV Tron using gas multiplication effect to current discharge and photoelectric effect of metal. To have high sensibility and to gain proper output voltage, it has high responsive performance. This research designed driving circuit with UV sensors and proposed method of false alarm reduced to resemble fire. the result propers the prevention and extinction of fire technique degree, certificated operation of detector.

• Journal of Periodontal and Implant Science
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• v.46 no.5
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• pp.329-336
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• 2016

Purpose: The aim of this study was to clinically assess the impact of a prefabricated implant-retained stent clipped over healing abutments on the preservation of keratinized mucosa around implants after implant surgery, and to compare it with horizontal external mattress sutures. Methods: A total of 50 patients were enrolled in this study. In the test group, a prefabricated implant-retained stent was clipped on the healing abutment after implant surgery to replace the keratinized tissue bucco-apically. In the control group, horizontal external mattress sutures were applied instead of using a stent. After the surgical procedure, the width of the buccal keratinized mucosa was measured at the mesial, middle, and distal aspects of the healing abutment. The change in the width of the buccal keratinized mucosa was assessed at 1 and 3 months. Results: Healing was uneventful in both groups. The difference of width between baseline and 1 month was $-0.26{\pm}0.85mm$ in the test group, without any statistical significance (P=0.137). Meanwhile, the corresponding difference in the control group was $-0.74{\pm}0.73mm$ and it showed statistical significance (P<0.001). The difference of width between baseline and 3 months was $-0.57{\pm}0.97mm$ in the test group and $-0.86{\pm}0.71mm$ in the control group. These reductions were statistically significant (P<0.05); however, there was no difference between the 2 groups. Conclusions: Using a prefabricated implant-retained stent was shown to be effective in the preservation of the keratinized mucosa around implants and it was simple and straightforward in comparison to the horizontal external mattress suture technique.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.27-37
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• 2024

The roof-filling body system stability plays a key role in gob-side entry retained (GER). Taking the GER of the 1103 belt transportation roadway in Heilong Coal Mine as engineering background, stability analysis of roof-filling body system was conducted based on the cusp catastrophe theory. Theoretical results showed that the current design parameters of 1103 belt transportation roadway could ensure the roof-filling body system stable during the resistance-increasing support stage of the filling body and the stable support stage of the filling body. Moreover, a verified global numerical model in FLAC3D was established to analyze the failure characteristics including surrounding rock deformation, stress distribution, and plastic zone. Numerical simulation indicated that the width-height ratio of the filling body had a great influence on the stability of the roof-filling body system. When the width-height ratio was greater than 0.62, with the decrease of the width-height ratio, the peak stress of the filling body gradually decreased; when the width-height ratio was greater than 0.92, as the distance to the roadway increased, the roof stress increased and then decreased. The theoretical analysis and numerical simulation findings in this study provide a new research method to analyze the stability of the roof-filling body system in GER.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.1
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• pp.21-30
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• 2013

The purpose of this study is to recognize the differences of visual evaluation by variations in silhouette of the wide pants. The stimuli are 9 samples: One control group, 3 variations of the width of hem line and 3 variations of the silhouette. The data has been obtained from 57 fashion college students. The data has been analyzed by Factor Analysis, Anova, Scheffe's Test. The results of the study are as follows: The visual evaluation by silhouette of wide pants are composed of 5 factors(i.e., physical characteristics, complexity, attractiveness, originality, and stiffness and softness). Among these factors, the physical characteristic is evaluated to be the most important factor. The straight pants were the most attractive and modern when the width of the hem line was 66cm (1st stage), while the pants were uncomfortable and unwearable when the width of the hem line was 98cm (3rd stage). The bell-bottom pants were evaluated to be the most attractive with the average width of the hem line. When the width of the hem line of the flare pants were too wide, it was uncomfortable and unwearable but had its unique originality. When the width of the hem line was narrow, the visual image changed as the pants' silhouette varied. However, when the width of the hem line was wide, the visual image did not change by silhouette.

• Geomechanics and Engineering
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• v.37 no.6
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• pp.555-563
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• 2024

The reasonable setting of coal pillar width plays a key role in guaranteeing the steadiness of surrounding rock of fully mechanized caving gateroad driving along the next goaf. Based on the engineering background of the Bayangaole mine, the discrete element method was used to simulate the fracture evolution of coal pillars with different pillar widths. The results show that the damage rate of the coal pillar increases with the decrease in the width of the coal pillar. Once the coal pillar width is smaller than 6 m, cracks run through the coal pillar, and the coal pillar is completely damaged. In the middle of the coal pillar, which has a width of 6 m and above, there is a relatively complete area with low damage. The results show that the pillar width of 6 m is the most appropriate. Field tests prove that the reserved width of a 6 m small coal pillar can effectively control the surrounding rock deformation, ensuring the overall steadiness of the gateroad in the thick coal seam. It is hoped that this study will offer some reference for the determination of the reasonable size of the coal pillar.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.149-159
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• 1996

Multipurpose development of the coast and ocean can be considered as multifunction construction combining the functions of coastal protection, waterfront amenity and creation or rehabilitation of habitats. Multfunction development of coastal and ocean spaces can be accomplished by applying the ecosystem control structure of artificial habitats which will cultivate fishing ground with ecological harmony to the coastal protection system. To evaluate the applicability of ecosystem control structures as as fundamental coastal protection structure, wave control function of the structure is studied by numerical and physical analyses. Dimensional analysis and hydraulic experiment point out the importance of width and crest depth of ecosystem control structure, construction water depth and wave steepness. Wave control efficiency is estimated by the attenuation coefficient $(K_H)$ according to wave steepness $(H_0/L_0)$, relative constructed water depth $(h_i/H_0)$, relative berm width $(B/L_0)$ and relative crest depth $(h_B/H_0)$ of eosystem control structure. Empirical fomulas are suggested based on the results of model test by applying the multiple model based on this experimental results and numerical wave shoaling-dissipation-breaking model appears to be valid for the analysis of wave transformation around ecosystem control structure in the coastal waters.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.530-535
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• 2002

Pneumatic control system has been applied to build many industrial automation systems. But most of them are sequence control type because of their low costs, safety, reliability, etc. Pneumatic servo system is rarely applied to real industrial fields because accurate position control is very difficult due to its nonlinearity and compressibility of air. In pneumatic servo control system, a pneumatic servo valve can be applied, But it is very expensive and has no advantage of low cost compared with a common pneumatic system. This paper is concerned with the accurate position control of a rodless pneumatic cylinder using on/off solenoid valve. A novel Intelligent Modified Pulse Width Modulation(MPWM) is newly proposed. The control performance of this pneumatic cylinder depends on the external loads. To overcome this problem, switching of control parameter using artificial neural network is newly proposed, which estimates external loads on rodless pneumatic cylinder using this training neural network. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied in the switching control the system. The effectiveness of the proposed control algorithms are demonstrated through experiments nth various loads.