• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2369-2379
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• 2013

A CMOS x-ray line scan sensor which is used in both medical imaging and non-destructive diagnosis is designed. It has a pixel array of 512 columns ${\times}$ 4 rows and a built-in DC-DC converter. The pixel circuit is newly proposed to have three binning modes such as no binning, $2{\times}2$ binning, and $4{\times}4$ binning in order to select one of pixel sizes of $100{\mu}m$, $200{\mu}m$, and $400{\mu}m$. It is designed to output a fully differential image signal which is insensitive to power supply and input common mode noises. The layout size of the designed line scan sensor with a $0.18{\mu}m$ x-ray CMOS image sensor process is $51,304{\mu}m{\times}5,945{\mu}m$.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.525-528
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• 2002

The proposed EMC filter composed with feed-through capacitors and ferrite beads of high permeability was prepared which satisfy the EMC standard for a wide-band noise signal in the frequence of 10 MHz to 1.5 GHz in power supply line. The optimum structure of ferrite bead was found by calculating the load effect of ferrite beads. As a result, the filter showed excellent differential- and common-mode noises filtering characteristics above 30dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8GHz.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.12-22
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• 1999

Operation of an electromagnetic shaker system using a Class-D amplifier may cause unacceptable electromagnetic interference to another electronic system, requiring the user to take whatever steps are necessary to correct the interference. A differential amplifier in a Class-D amplifier is used to decrease the effect of a common-mode noise voltage in a shaker system. To prevent a ground loop, a transformer is inserted in another shaker system. These methods show reduction of the unwanted vibration which has occurred before. A transformer in a charge amplifier was used to prevent a ground loop in a shaker system using a Class-AB amplifier a few years ago, but it was susceptible of noise in a shaker system using a Class-D amplifier. Hence we corrected a ground loop between a charge amplifier and a vibration control/analysis system without a transformer. The usefulness of this approach is illustrated by the results of experiments.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.223-224
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• 2015

배전 계통 산업 현장에서는 스위칭 소자 및 제어장치, 전 자기기들이 한 대 맞물려 증가하고 있다. 또한, 스마트 그리드(Smart Grid) 및 마이크로 그리드(Micro Grid)의 개념이 도입되면서 분산 전원 이 널리 보급되고 있다. 이로 인해 현장에서는 많은 전기전자기기들이 설치되어 운영 중에 있고, 이것은 noise 및 고조파와 같은 왜란이 발생 되는 원인을 초래하고 있다. 왜란은 여러 전기 전자 장비들의 데이터 취득 왜곡 현상을 발생시키고, 이러한 데이터 손실로 인해 기기들의 오동작 및 사고를 발생시킨다. 대표적인 왜란으로는 common mode noise 같은 대지(大地) 등의 기준점과 각 신호선 사이에 나타나는 노이즈가 있으며, 선로 및 장비 특성에 따라 기수 및 우수 고조파가 있다. 이러한 왜란들은 전자기기들의 오동작 및 신호의 부 정확성으로 제품 신뢰성에 문제를 초래한다. 특히 데이터 계측 실패 및 Serial 통신을 함에 있어서 신호 손실을 발생시켜 데이터 변형을 초래한다. 이로 인해 배전선로에 위치한 전자기기들이 왜곡된 데이터로 동작을 하게 되고 이는 곧 선로의 사고를 발생시키게 된다. 따라서 왜란들을 사전에 방지하여 기기 오동작 및 부동작을 예방하기 위해서 산업계에서는 왜란에 대한 인식을 지속적으로 증가시키고 있다. 실제 현장에서도 이와 같은 왜란으로 인해 기기 오동작을 하는 경우가 많으며 이를 해결하기 위한 여러 신호처리 기법을 적용하고 있다. 이에 본 논문에서는 여러 종류의 샘플링 데이터 량을 생성할 수 있도록 샘플링 속도를 다변환(Multi-interchange)하고 각 샘플링 속도에 맞게 계측된 샘플링 데이터를 DFT 신호 처리하여 왜란으로부터 강건한 계통 주파수를 계측한다. 또한, 주파수 별 DFT 값을 Table화 하여 계통 주파수를 찾아낸다.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.54-61
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• 2012

The WAVE specification, which for the Next-Generation ITS environment is a common title: IEEE 802.11p and IEEE P1609 specifications. These days, there are many activities for researching WAVE specification by release of the IEEE 802.11p specification. The difference between high-speed vehicle environment and the indoor environment, the wireless communication channel mode is that much more severe. Thus, the wireless communication system design, temperature, noise, multipath fading and can degrade the performance of the system points should be fully considered matters of. In this paper, we showed WAVE wireless communication system which based on IEEE 802.11p PHY/MAC design process, and also showed solving process many implementation problems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.71-79
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• 2008

This paper analyzed the voltage induction phenomena on the telecommunication lines by electromagnetic coupling from high-speed A.C. electrified railway. The induced common mode voltages and the induced differential mode voltage on the telecommunication line was measured by notified standard method in the regulation of Korea. The test lines consist of 2 separated lines of 20 m and 300 m in influence distance each for comparison, with 2km inducing length. The analysis is made on the induced voltages from the different influence distances and the different earthing points, and also on the waveform and spectrum distributions. It is proved that the induction is arisen so good and the measured values are fair enough against noise such as the earth voltage differencing, and the current measuring scheme is also rightful.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.299-307
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• 2009

Emerging fiber optic sensor technologies have shown great potential to overcome the difficulties associated with conventional sensors. Fiber optic sensors are immune to EM noise and electric shock and thus can be used in explosion-prone areas. Several kinds of fiber optic sensors have been developed over the last two decades to take advantage of these merits. There have also been many field applications of fiber optic sensors for structural health monitoring as NDT/HDE. However, very few sensors, particularly a load cell have been successfully commercialized. This Paper Presents a load cell using fiber Bra99 gra1ing (FBG) sensors. The shape of the load cell is a link type, and three FBG sensors are used for measuring strains at three different points. Especially, these strains are processed with a differential method in order to exclude common mode noise such as temperature. Moreover, the sensitivity, the linearity and the resolution of the load cell were successfully verified from the experiment of tension test.

• Journal of Korean Academy of Nursing
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• v.40 no.5
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• pp.736-746
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• 2010

Purpose: This study was done to identify the distribution and related factors for stage of change for wearing hearing protection devices (HPDs) by workers in environments with high noise. Predictors of Use of Hearing Protection Model and Trans-theoretical Model were tested. Methods: The participants were 755 workers from 20 noisy work places in Busan and Gyeongnam. Data were collected from January to April 2008 using self-administered questionnaires, and analyzed using multiple logistic regression. Results: There were significant differences in social mode (OR=1.35, 95% CI: 1.06-1.73) between precontemplation/contemplation and preparation stage, in males (OR=2.36, 95% CI: 1.24-4.51), workers with high school education or less (OR=1.39, 95% CI: 1.28-2.78), shift workers (OR=1.50, 95% CI: 1.02-2.21), workers who previously worked in noisy places (OR=1.39, 95% CI: 1.20-2.34), and workers who had previous hearing examinations (OR=1.89, 95% CI: 1.25-2.85), in the social model (OR=1.59, 95% CI: 1.42-1.78), and self-efficacy (OR=1.05, 95% CI: 1.02-1.08) between workers in preparation and action stages, in length of time working in noisy work places (OR=2.26, 95% CI: 1.17-4.39), social model (OR=1.66, 95% CI: 1.33-2.08), and perceived benefit (OR=0.95, 95% CI: 0.93-0.97) between action and maintenance stage. Conclusion: Social model was a common factor showing differences between two adjacent stages for wearing HPDs. The results provide data for developing programs to encourage workers to wear HPDs and application of these programs in work settings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.587-593
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• 2021

Since 2017, a total of 29 fire accidents have occurred in energy storage systems (ESSs) as of June 2020. The common mode voltage (CMV) is one of the electrical hazards that is assumed to be a cause of those fire accidents. Several cases of CMV that violate the allowable insulation level of a battery section are being reported in actual ESS operation sites with △-Y winding connections. Thus, this paper evaluates the characteristics of CMV. An ESS site was modeled with an AC grid, PCS, and battery sections using PSCAD/EMTDC software. As a result of a simulation based on the proposed model, it was confirmed that characteristics of CMV vary significantly and are similar to actual measurements, depending on the grounding method of the internal transformer for PCS. The insulation level of the battery section may be severely degraded as the value of CMV exceeds the rated voltage in case of a grounding connection. It was found that the value of CMV dramatically declines when the internal transformer for PCS is operated as non-grounding connection, so it meets the standard insulation level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1252-1260
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• 1999

The HFC network has a architecture of a star topology in fiber optic trunks, and tree and branch topology is used in the part of coaxial cable. It is well known that the HFC upstream channel is noisy. Ingress, common mode distortion and impulse noise exist in the upstream channel. In order to provide Quality of Service(QoS) to users with real-time data such as voice, video and interactive services, the evolving IEEE 802.14 standard for HFC networks must include an effective priority scheme. The scheme separates and resolves collisions between stations in a priority order. It is important to simulate protocols under a practical environment. The proposed algorithm in this paper is simulated with the assumption that the collision detector made certain mistake due to noises. Simulation results show that the proposed algorithm is more efficient than existing tree-based algorithm under practical environment.