• 한국인터넷방송통신학회논문지
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• 제21권4호
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• pp.129-134
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• 2021

전동공구는 동력원인 모터를 이용하여 각종 구조물을 제조 가공하는데 사용되는 공구로 전기를 동력원으로 한 모터를 사용하여 감속장치, 동력전달 및 변환장치 기능을 내장시켜 도구에 회전, 왕복, 진동 운동을 시킴으로써 사용자의 동작기술을 보조하는 역할을 하도록 한 공작용 도구이다. 우리나라의 경우 전동공구 산업은 역사가 짧아서 독일이나 미국, 일본 등 선진국에 비하여 기술수준과 시장 점유율, 인지도 등이 뒤떨어지고 있다. 또한 국내에서 사용되는 전동 Driver는 미국, 유럽 나라의 해외제품으로 국내시장 또한 100% 해외업체 것을 선호하며 다국적 기업들이 국내 시장에 많은 투자를 하고 있는 실정이다. 따라서 국내 기술개발과 지속적으로 높은 시장점유율을 확보하기 위해서는 기술적인 개발이 뒤따라야 한다. 본 논문에서는 전동공구의 기본요구 성능에 맞춰 모터의 성능, 소형화, 고속도의 고출력 성능을 가지는 전동기 Driver를 설계하여 최종적으로 산업용 및 의료용에 적용할 수 있는 개발품을 연구하는데 목적을 두고 있다.

• Design & Manufacturing
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• 제15권4호
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• pp.65-71
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• 2021

In the early days of laser invention, it was simply used as a measuring tool, but as lasers became more common, they became an indispensable processing tool in the industry. Short-wavelength lasers are used to make patterns on wafers used in semiconductors depending on the wavelength, such as CO2 laser, YAG laser, green laser, and UV laser. At first, the hole of the PCB board mainly used for electronic parts was not thin and the hole size was large, so a mechanical drill was used. However, in order to realize product miniaturization and high integration, small hole processing lasers have become essential, and pattern exposure for small hole sizes has become essential. This paper intends to analyze the characteristics through patterns by exposing the PCB substrate through DMD and polygon scanner, which are different optical systems. Since the optical systems are different, the size of the patterns was made the same, and exposure was performed under the optimal conditions for each system. Pattern characteristics were analyzed through a 3D profiler. As a result of the analysis, there was no significant difference in line width between the two systems. However, it was confirmed that dmd had better pattern precision and polygon scanner had better productivity.

• 한국표면공학회지
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• 제55권2호
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• pp.102-119
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• 2022

Gold plating is used as a coating of connecter in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. As increasing the demand for miniaturization of printed circuit boards and downsizing of electronic devices, several types of electroless gold plating solutions have been developed. Most of these conventional gold plating solutions contain cyanide compounds as a complexing agent. The gold film obtained from such baths usually satisfies the requirements for electronic parts mentioned above. However, cyanide bath is highly toxic and it always has some possibility to cause serious problems in working environment or other administrative aspects. The object of this investigation was to develop a cyanide-free electroless gold plating process that assures the high stability of the solution and gives the excellent solderability of the deposited film. The investigation reported herein is intended to establish plating bath composition and plating conditions for electroless gold plating, with thiomalic acid as a complexing agent. At the same time, we have investigated the solution stability against nickel ion and pull strength of solder ball. Furthermore, by examining the characteristics of the plated Au plating film, the problems of the newly developed electroless Au plating solution were improved and the applicability to various industrial fields was examined. New type electroless gold-plating bath which containing thiomalic acid as a complexing agent showing so good solution stability and film properties as cyanide bath. And this bath shows the excellent stability even if the dissolved nickel ion was added from under coated nickel film, which can be used at the neutral pH range.

• 한국인터넷방송통신학회논문지
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• 제22권2호
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• pp.35-42
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• 2022

본 논문에서는 SSPA(Solid state amplifier) 의 핵심 모듈인 결합기의 효율 및 격리 특성을 높이는 방법에 대해 연구하였다. 구체적으로 도파관 결합기에서 공용 포트와 격리 포트 정합을 이루어 격리도를 확보 하였다. 정합을 위한 매칭 구조는 원형 디스크 형태로 도파관 결합기 내부에서 음각으로 가공하게 된다. 구조는 매우 단순하여 안정적인 성능 확보가 가능하다. 그리고 이러한 구조는 이전 연구 대비 60배 이상의 높은 임계전력 성능을 보여 고출력에 적합함을 확인하였다. 그리고 1단의 T-junction과 2, 3단의 MagicT 결합기를 조합하여 소형화를 이루고, 삽입손실을 줄여 결합 효율을 최적화 하였다. 제작된 도파관 결합기는 16dB 이상의 격리도와 86.2% 의 결합 효율을 얻었다.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.353-358
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• 2022

Bulky iron-core potential transformers (PT) are installed in a tank of gas insulated switchgears (GIS) for a system voltage measurement in power substations. In this paper, we studied an electronic voltage transformer (EVT) embedded in a spacer for miniaturization, eco-friendliness, and performance improvement of GIS. The prototype EVT consists of a capacitive probe (CP) that can be embedded in a spacer and a voltage Follower with a high input and a low output impedance. The CP was fabricated in the form of a Flexible-PCB to acquire the insulation performance and to withstand vibration and shock during operation. Voltage ratio of the prototype EVT is about 42,270, and the frequency bandwidth of -3 dB ranges from 0.33 Hz to 3.9 MHz. The voltage ratio error evaluated at about 6%, 12% and 18% of the rated voltage of 170 kV was 0.32%, and the phase error was 12.9 minutes. These results were within the accuracy for the class 0.5 specified in IEC 60044-7 and satisfy even in ranges from 80% to 120% of the rated voltage. If the prototype EVT replaces the conventional iron-core potential transformer, it is expected that the height of the GIS could be reduced by 11% and the amount of SF₆ will be reduced by at least 10%.

• 마이크로전자및패키징학회지
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• 제29권2호
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• pp.65-71
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• 2022

Mobile PKG Trend는 소형화와 더불어 고용량 제품 요구로 인해 Mold Top Margin 감소가 불가피한 상황이다. 하지만 기존 Laser Marking 공법은 Depth가 깊어 Narrow Top Margin 제품에 적용할 때 중첩 가공에 의한 PKG 강도 저하가 예상되며, Chip Damage와 같은 품질 불량으로 신뢰성이 저하되는 문제점이 있다. 따라서 본 연구에서는 Laser Source 특징 비교를 통해 Narrow Top Margin 제품에 대응할 수 있는 Low Depth Laser Marking 기술을 확보하였으며, PKG 개발 제품에 해당 기술을 적용하여 평가한 결과 Marking Depth 67% 감소와 PKG 강도 12%가 향상됨을 검증하였다. 또한 PKG Mechanical 분석을 통해 발생 가능한 Laser Damage 품질 검증을 진행하였고, Chip Damage(Crack/Chipping) 불량은 발견되지 않았다. 이를 통해 양산 적용 품질 안정성을 확보하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.62-67
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• 2022

Liquid hydrogen (LH₂) has a higher density than gaseous hydrogen, so it has high transport efficiency and can be stored at relatively low pressure. In order to use efficient bulk hydrogen in the industry, research for the LH₂ supply system is needed. In the high-pressure hydrogen station based on LH₂ currently being developed in Korea, a heat exchanger is used to heat up supercritical hydrogen at 700 bar and 60 K, which is pressurized by a cryogenic high-pressure pump, to gas hydrogen at 700 bar and 300 K. Accordingly, the heat exchanger used in the hydrogen station should consider the design of high-pressure tubes, miniaturization, and freezing prevention. A helical heat exchanger generates secondary flow due to the curvature characteristics of a curved tube and can be miniaturized compared to a straight one on the same heat transfer length. This paper evaluates the heat transfer performance through parametric study on the distance between coils, guide effect, and anti-icing design of helical heat exchanger. The helical heat exchanger has better heat transfer performance than the straight tube exchanger due to the influence of the secondary flow. When the distance between the coils is uniform, the heat transfer is enhanced. The guide between coils increases the heat transfer performance by increasing the heat transfer length of the shell side fluid. The freezing is observed around the inlet of distribution tube wall, and to solve this problem, an anti-icing structure and a modified operating condition are suggested.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.47-51
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• 2022

With the innovative development of bio, pharmaceutical, and semiconductor technologies, it is essential to demand a next-generation transfer system that minimizes dust and vibrations generated during the manufacturing process. In order to develop dust-free and non-contact transfer systems, the high temperature superconductor (HTS) bulks have been applied as a magnet for levitation. However, sintered HTS bulk magnets are limited in their applications due to their relatively low critical current density (J_c) of several kA/cm² and low mechanical properties as a ceramic material. In addition, during cooling to cryogenic temperatures repeatedly, cracks and damage may occur by thermal shock. On the other hand, the bulk magnets made by stacked HTS tapes have various advantages, such as relatively high mechanical properties by alternate stacking of the metal and ceramic layer, high magnetic levitation performance by using coated conductors with high J_c of several MA/cm², consistent superconducting properties, miniaturization, light-weight, etc. In this study, we tried to fabricate HTS tapes stacked bulk magnets with 60 mm × 60 mm area and various numbers of HTS tape stacked layers for magnetic levitation. In order to examine the levitation forces of bulk magnets stacked with HTS tapes from 1 to 16 layers, specialized force measurement apparatus was made and adapted to measure the levitation force. By increasing the number of HTS tapes stacked layers, the levitation force of bulk magnet become larger. 16 HTS tapes stacked bulk magnets show promising levitation force of about 23.5 N, 6.538 kPa at 10 mm of levitated distance from NdFeB permanent magnet.

• 한국전자통신학회논문지
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• 제17권6호
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• pp.1175-1180
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• 2022

STI는 반도체 소자의 소형화 및 고집적화에 따른 광역 평탄화를 위한 공정 기술로써 많은 연구가 이루어져 왔다. 본 연구에서는 STI의 profile 개선을 위한 방법으로 STI 건식각 후 HF 용액에 의한 pad oxide 습식각과 O₂+CF₄ 건식각을 제안하였다. 이 공정 기술은 기존의 방법보다 소자의 밀집도에 따른 패턴간의 프로파일 불균형과 누설전류의 개선을 나타내었다. 또한 동일한 STI 깊이와 HLD 증착를 갖는 디바이스에 대하여 CMP 후 HLD 두께를 측정한 결과 디바이스 밀도에 따라 측정값이 다르게 나타났고 이는 CMP 후 디바이스 밀도에 따른 질화막의 두께 차이 및 슬러리의 선택비에 기인됨을 확인하였다.

• 한국인터넷방송통신학회논문지
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• 제22권1호
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• pp.121-126
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• 2022

본 연구는 변형된 힐버트 커브 프랙탈 모노폴 구조를 단순화하여 육각형 대칭 패턴을 가지면서 모노폴 형태로 구현한 안테나에 대한 것이다. 힐버트 커브 프랙탈 모노폴 구조를 단순화하여 소형화했을 뿐 아니라 성능 개선을 모색하기 위해 복사기 구조를 육각형 대칭 패턴으로 구현했다. 기판 유전체의 비유전율은 4.7이며, 미앤더 형태로 대칭 구조를 갖는 총 선로길이는 59 mm이다. 안테나의 크기는 10 mm × 10 mm × 0.8 mm이고, 선폭은 0.4 mm이다. 안테나 측정 지그의 크기는 64 mm × 21 mm × 1 mm이다. 공진주파수는 1.57 GHz 이고, 주파수 범위는 1.51 ~ 1.615 GHz이다. 주파수대역폭은 105 MHz이다. 안테나 이득은 YZ-plane의 측정이득은 2.32 dBi 이고, XZ-plane의 경우 -1.03 dBi를 얻었다. 결과적으로 육각형 대칭 패턴 프랙탈 구조를 이용하여 안테나 소형화를 이루었으며, 복사기 구조 변화로 안테나 성능 개선이 용이함을 확인했다.