• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.670-672
• /
• 2014

In this study, we investigate active control of noise transmitted through a window of enclosures minimizing the acoustic power. To reduce noise of the enclosures, passive methods with absorbing material are generally used. The passive methods, however, are limited use due to the vantilation windows. In this case, these windows are path of noise leakage. Feedforward active noise control technology is applied to minimize the sound power from the enclosure. The feedforward controller is implemented with FIR filter based on the transfer functions calculated numerically. The controller reflects the delay due to FIR filter. The noise transmitted through the window is actively controlled, and the reduction of the power is obtained by 15dB.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 추계학술대회 논문집
• /
• pp.733-738
• /
• 2012

This paper presents active noise control for the reduction of transmission noise passing through opening of enclosures. Enclosures are essential measure to protect noise propagation from operating machinery. Access openings of the enclosures are important path of noise leakage. First, we modeled and analyzed the noise characteristics passing through the openings of the enclosure generated by the operation of the machinery based on the finite element method. We then implemented a feedforward controller to actively control the acoustic power through the opening. Finally, we conducted optimization of placement of the reference sensors for several cases of the number of sensors. A good control performances were achieved using a minimum number of microphones arranged a optimal placement.

• 전기의세계
• /
• 제29권10호
• /
• pp.653-659
• /
• 1980

The paper describes a new technique for the shape design of a bell-type porcelain locke insulator in contaminated environment. Early studies on the contamination performance of insulators indicated the need for an improvable shape to provide adequate insulation strength at normal operating voltages. In this paper, under lightly and heavily contaminated site severity, the variation of voltage distribution to leakage path at insulator surfaces analyzed by the complex admittance matrix using finite element method. By this results, the improvement of shape of insulators could be approached to the available condition in contaminated environments. In applicating to compare a standard disc type with a fog disc type insulator, this design technique is valid.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
• /
• pp.246-248
• /
• 2004

The lower voltage distribution box of service wire has been usually employed to supply an electric power to the consumers through low voltage overhead line. Now-a-days, electric shock accident at the distribution box of service wire installed in the seashore areas has been often occurred. The reason is mainly due to the electric leakage in the distribution box of service wire. This paper described insulation breakdown mechanism of distribution box of service wire, analysis of electric shock path and safety countermeasure of distribution box of service wire.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 추계학술대회 논문집
• /
• pp.281-285
• /
• 2008

Corrosion of metallic structures arises when an electric current flows from the metal into the electrolyte such as soil and water. The potential difference across the metal-electrolyte interface, the driving force for the corrosion current, can emerge due to a variety of temperature, pH, humidity and resistivity etc.. With respect to a given structure, a stray current is to be defined as a current flowing on a structure that is not part of the intended electrical circuit. Stray currents are caused by other cathodic protection installations, grounding systems and welding posts, referred to as steady state stray currents. But most often traction systems like railroads and tramlines are responsible for large dynamic stray currents. This type of stray current is generally results from the leakage of return currents from large DC traction systems that are grounded or have a bad earth-insulated return path. This paper investigates the reports, which is made for protecting the electrical corrosion by the DC traction stray current before the construction period.

• Journal of Power Electronics
• /
• 제19권1호
• /
• pp.296-306
• /
• 2019

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondary windings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used to effectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In this paper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter with synchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with a transformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, good heat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulation tool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCB transformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.

• 한국정보통신학회논문지
• /
• 제20권10호
• /
• pp.1927-1934
• /
• 2016

본 논문에서는 일반적인 실리콘 기반 n-MOSFET(n-type Metal Oxide Semiconductor Field Effect Transistor)의 절연 산화막 계면에서 방사선으로부터 유발되는 누설전류 경로를 차단하기 위하여 I형 게이트 n-MOSEFT 구조를 제안하였다. I형 게이트 n-MOSFET 구조는 상용 0.18um CMOS(Complementary Metal Oxide Semiconductor) 공정에서 레이아웃 변형 기법을 이용하여 설계되었으며, ELT(Enclosed Layout Transistor)와 DGA(Dummy Gate-Assisted) n-MOSFET와 같은 레이아웃 변형 기법을 사용한 기존 내방사선 전자소자의 구조적 단점을 개선하였다. 따라서, 기존 구조와 비교하여 반도체 칩 제작에서 회로 설계의 확장성을 확보할 수 있다. 또한, 내방사선 특성 검증을 위하여 TCAD 3D(Technology Computer Aided Design 3-dimension) tool을 사용하여 모델링과 모의실험을 수행하였고, 그 결과 I형 게이트 n-MOSFET 구조의 내방사선 특성을 확인하였다.

• 한국항행학회논문지
• /
• 제12권3호
• /
• pp.220-226
• /
• 2008

본 논문에서는 ${\lambda}/4$ 임피던스 변환기를 피킹 증폭기 뒷단에 배치하고, 주 증폭기와 피킹 증폭기가 서로 다른 비대칭 구조의 도허티 증폭기 만들어 효율을 개선시키는 방법을 제시하였다. 이러한 구조는 다단 도허티 증폭기 구현 시 작은 크기로 구현이 가능하며, 기존의 전기적 특성과 동일함을 시뮬레이션을 통해서 확인하였다. 이러한 구조를 갖는 전력 증폭기를 제작하였으며, W-CDMA 기지국 송신 대역에서 IFA 신호를 인가하였을 때, 45W 출력 기준으로 8dB 백-오프 지점에서 26.3%의 전력부가효율을 얻었고, 중심 주파수에서 ${\pm}5MHz$이격 지점 에서 -40.4dBc의 인접채널 누설비 (Adjacent Channel Leakage Power : ACLR)를 확인하였다.

• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.1226-1235
• /
• 2016

For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 mm², while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.

• 디지털융복합연구
• /
• 제17권9호
• /
• pp.1-12
• /
• 2019

본 연구는 SNS 게시물 기록화 수용의도에 미치는 요인들을 탐색하였으며, SPSS 21.0 프로그램과 AMOS 21.0 프로그램을 활용, 탐색적 요인분석과 확인적 요인분석, 상관관계 분석, 경로분석 등을 통해 주요 결과를 도출하였다. 주요 결과를 살펴보면, 첫째, SNS 게시물 기록화에 대한 개인정보 유출 위험은 SNS 게시물 기록화에 대한 태도에 통계적으로 유의한 부적 영향을 미치는 것으로 나타났다. 둘째, SNS 게시물 기록화에 대한 보안은 SNS 게시물 기록화에 대한 태도에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 셋째, SNS 게시물 기록화에 대한 프라이버시 염려는 SNS 게시물 기록화에 대한 태도에 통계적으로 유의한 부적 영향을 미치는 것으로 나타났다. 넷째, SNS 게시물 기록화에 대한 태도는 SNS 게시물 기록화 수용의도에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 이상의 결과는 SNS 게시물 기록화의 경우에 장기적인 관점에서 SNS 사용자들의 의견을 충분히 수렴해야 함을 시사한다.