• Journal of Positioning, Navigation, and Timing
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• v.5 no.3
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• pp.119-129
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• 2016

This paper presents an integrated navigation system for accurate navigation solution-based safety and convenience services in the vehicular augmented reality (AR)-head up display (HUD) system. For lane-level guidance service, especially, an accurate navigation system is essential. To achieve this, an inertial navigation system (INS)/global positioning system (GPS)/vision/digital map (IGVM) integrated navigation system has been developing. In this paper, the concept of the integrated navigation system is introduced and is implemented based on a multi-model switching filter and vehicle status decided by using the GPS data and inertial measurement unit (IMU) measurements. The performance of the implemented navigation system is verified experimentally.

• The Journal of the Acoustical Society of Korea
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• v.5 no.1
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• pp.24-34
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• 1986

Recently, as the noise problems of mechancial structures have been more serious, much studies are being carried out on the identification of noise sources and the reduction of noise level. In this paper, as the application of frequency analysis, the multi-dimensional spectral analysis method is applied to daisy wheel printer to identify the noise sources, and the relationship between sound pressure and vibration of printer is found in narrow and overall frequency range. The results of this study are compared with those of frequency response function method, thus, the applicability of multidimensional spectral analysis method is verified. It can be found, in a overall frequency range, that the vibration of platen have the worst effect on noise level, and the noise level reduction of 6dB, 7.9dB is obtained by changing the platen thickness to 2mm, 4mm, respectively.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.630-634
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• 2003

This paper proposes a Carrier-Rotation PWM technique that is new solution for the voltage unbalancing problem of flying capacitors in the Flying Capacitor Multi-level Inverter (FCMI).The proposed PWM technique equalizes the utilization of phase leg voltage redundancies corresponding to the charging and the discharging state of flying capacitors during one switching period of all the switches. it also has the same switch utilization and the reduced harmonics of output voltage. Hence, it is more suitable for the FCMI compared with the conventional solutions. Experimental results on the laboratory prototype flying capacitor 3-level inverter confirm the validity of the proposed PWM technique.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.147-155
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• 2000

To reduce the noise from wood cutting saw at the saw mill(lumber mill) or a construction area, some multi-layer sandwich saw blades which a aluminum or copper plate was inserted between the two steel plates were developed and were tested of the wood cutting noise level at various test places. From the research, it was found that the multi-layer saw blade with copper or aluminum plate between steel plates and spot welded 60 points could reduce the wood cutting sound level about 8.3 dB(97.031 dB - 88.743 dB) at indoor test and 3.8 dB(84.805 - 81.638 dB) at field test.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.311-315
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• 2002

Chemical mechanical polishing (CMP) process was required for the global planarization of inter-metal dielectric(IMD), inter-level dielectric (ILD) layers of multi-layer interconnections. In this paper, we studied the characteristics of polishing pad, which can apply shallow trench isolation (STI)-CMP process for global planarization of multi-level interconnection structure. Also, we investigated the effects of different sets of polishing pad, such as soft and hard pad. As an experimental result, hard pad showed center-fast type, and soft pad showed edge-fast type. Totally, the defect level has shown little difference, however, the counts of scratch was detected less than 2 on JR111 pad. Through the above results, we can select optimum polishing pad, so we can expect the improvements of throughput and device yield.

• ETRI Journal
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• v.41 no.6
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• pp.863-872
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• 2019

Elliptic curve cryptography is a relatively lightweight public-key cryptography method for key generation and digital signature verification. Some lightweight curves (eg, Curve25519 and Curve Ed448) have been adopted by upcoming Transport Layer Security 1.3 (TLS 1.3) to replace the standardized NIST curves. However, the efficient implementation of Curve Ed448 on Internet of Things (IoT) devices remains underexplored. This study is focused on the optimization of the Curve Ed448 implementation on low-end IoT processors (ie, 8-bit AVR and 16-bit MSP processors). In particular, the three-level and two-level subtractive Karatsuba algorithms are adopted for multi-precision multiplication on AVR and MSP processors, respectively, and two-level Karatsuba routines are employed for multi-precision squaring. For modular reduction and finite field inversion, fast reduction and Fermat-based inversion operations are used to mitigate side-channel vulnerabilities. The scalar multiplication operation using the Montgomery ladder algorithm requires only 103 and 73 M clock cycles on AVR and MSP processors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.2
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• pp.167-175
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• 1999

B.P.F.(Blade Passing Frequency) levels were measured with the cut-off clearance changes. The velocity inside the scroll, pressure fluctuation at cut-off region, and the scroll surface pressure distribution along the scroll from the cut-off to outlet were measured. With a certain cut-off clearance the improvement of efficiency and attenuation of B.P.F. noise level could be achieved. The measured results of pressure fluctuation and scroll surface pressure distribution showed that the secondary flow inside the scroll increased B.P.F. noise level at the cut-off region as the cut-off clearance got wide.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.116-121
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• 2004

This paper proposes a novel UPFC based on 3-level Half-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC, assuming that the UPFC is connected with the 138-kV transmission line of one-machine-infinite-bus power system. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of 3-level Half-bridge modules.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.59-60
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• 2015

본 논문에서는 직류송전 적용을 위해 전력계통과 연계된 모듈형 멀터레벨 컨버터(Modular Multi-level Converter)의 유 무효 전력제어에 대해 시뮬레이션 모델을 개발하고 그 특성을 분석하였다. 분석에 고려한 모듈형 멀티레벨 컨버터는 한 암당 12개의 서브모듈로 구성되어 있고 모듈레이션은 NLC (Nearest Level Control) 방식을 사용한다. 또한 DC 커패시터의 밸런싱은 버블소팅 방식을 적용하였고 순환전류를 억제하는 알고리즘을 고려하였다. 시뮬레이션을 통해 분석한 유 무효전류제어를 실험적으로 검증하기 위해 10kVA DC 1000V 하드웨어 축소모형을 제작하고 실험을 실시하였다. 실험결과는 시뮬레이션 결과와 일치함을 확인할 수 있었다. 향후에는 교류전압 불평형 보상과 순환전류 제어, 컨버터 보호에 대한 다양한 알고리즘을 도출할 예정이다.

• Journal of the Korea Society for Simulation
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• v.11 no.1
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• pp.59-70
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• 2002

This article presents the results of research to develop a descriptive model of firm-level productivity that will allow a myriad of factor interactions to be directly accounted for. The model is a linked set of equations that attempt to capture how changes in one-factor influences the level of another factor. and ultimately bottom-line performance. The model is coded in SIMAN. It is used to determine the best use of an infusion of funds should they go for additional automation, or training etc. An application of the model to U.S. industry is presented based on parameter values obtained through a national survey.