• Restorative Dentistry and Endodontics
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• 제35권4호
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• pp.246-256
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• 2010

수종의 근관치료용 전기모터들의 반복사용과 시간에 따른 회전속도의 변화를 비교하여 근관치료용 전기모터의 회전 안정성을 평가하고자 하였다. 시간에 따라 변화하는 실제회전속도 및 전압과 전류를 측정하고, Student t-test를 통한 실제회전속도와, 반복측정분석을 통한 상관관계를 비교분석 하였다. 동일 종류의 전기모터들 사이의 모든 측정 결과들은 차이를 보이지 않았다. 모든 전기모터에서 반복사용과 시간의 흐름에 따른 회전속도의 변화는 차이를 보이지 않았다. 이상의 결과로, 본 실험에 사용된 모든 전기모터는 일정한 회전속도를 유지해야 하는 회전 안정성의 조건에 충족됨을 알 수 있으며, 반복사용과 시간에 따른 신뢰성 있는 회전속도와 안정적인 전압 및 전류의 유지가 가능하리라 생각된다.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.378-385
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• 2016

전기 분 배전반의 내부 회로 인 부스 바는 충전부의 노출로 인해 전기 사고의 원인이 되며 이로 인한 감전 사고와 단락 사고가 발생된다. 또한 동물 및 이물질 침투로 인한 전기 화재 사고가 발생되는 원인이 되기도 한다. 또한 확장이 불가능한 구조로 무리하게 연결하여 사용하므로 접촉 저항 증가 발생으로 과열 사고를 유발시키기도 하며, 절단과 절곡 등의 제조 공정상의 어려움을 가지고 있기 때문에 주문생산방식을 택할 수밖에 없는 현실이며, 긴급전기 사고 발생시 복구하는데 지연되는 원인이 되기도 한다. 본 논문에서는 이와 같은 문제점을 개선하기 위해서 분 배전반의 모선을 절단하여 개별 블록으로 절연 난연 케이스와 격벽 구조화로 안전성을 높여 모듈 블록화 하였으며, 확장성과 유연성을 구현하였으며, 쉽게 확장이 가능한 구조이며, 또한 쉽게 분 배전반을 조립할 수 있다는 것이며, 이와 같이 전기적 위험 요소를 제거한 전기 분 배전반의 내부 구조는 블록형 부스 바 구조를 가지고 메인차단기와 분기차단기간의 회로 형성 구현 방식의 분 배전반를 제안하고 공인시험기관의 시험을 통해 그 유용성을 입증 하였다.

• Journal of Welding and Joining
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• 제31권5호
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• pp.54-58
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• 2013

Joint properties of vehicle ECU (Electric Control Unit) module which was manufactured by using Sn-Cu-Cr-Ca alloy were investigated. A new solder which has a middle melting temperature about $231^{\circ}C$ was fabricated as the type of 300um solder ball and paste type. The prototype modules were made by reflow process and measured spreadability, wettability shear strength and estimated interface reaction. The spreadability of the alloy was about 84% from the measurement of contact angle of the solder ball and the wetting force was measured 2mN. The average shear strength of the module which was manufactured by using the solder paste, was 1.9 $kg/mm^2$. Also, the thickness of IMC(intermetallic compound) was evaluated with various aging temperature and time in order to understand Cr effect on Sn-0.7Cu solder. $Cu_6Sn_5$ IMC was formed between Cu pad and the solder alloy and the average thickness of the $Cu_6Sn_5$ IMC was measured about 4um and it was about 50% of thickness of $Cu_6Sn_5$ IMC in Sn-0.7Cu. It is expected to have a positive effect on reliability of the solder joint.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.996-1001
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• 2006

Automatic washing machines have been improved and popularized steadily since the first electric washing machine was produced in the early 1900's. Appliance industry has tried to obtain the performance of washing machine with large capacity, high energy efficiency, low vibration and low noise levels. As the installation peace of a washer becomes closer to the living space, vibration and noise problems become more important challenges. In general, a washing machine has four legs to support its body. Four legs of the washing machine should be attached on a floor. If not so, it may cause severe vibration or walking in the spin-drying process. Unfortunately, the floor of an ordinary house is bumpy in general, and the consumers will not accept bolting washing machines to a foundation; moreover, sometimes they move the location of their washing machines to utility rooms or bath rooms or kitchens and don't care for leveling the legs exactly. In this study, we devise an auto-leg system that prevents the occurrence of abnormal vibration and walking of washing machines. It is simply composed of a spring and a friction damper. Some experiments are implemented to show the dynamic characteristics of the three-dimensional auto-legged washing machine model that is located on the even or uneven ground. A spring parameter is optimized to adjust the length of the auto-leg system automatically up to 10 mm irregularity, and the friction damper is designed to decrease a resonance induced by the spring of the auto-leg system. Some numerical results show that placing the proposed auto-leg system in a washing machine makes good performance with low vibration, as well as low noise, regardless of the unevenness of the floor.

• 대한의용생체공학회:의공학회지
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• 제26권3호
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• pp.139-144
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• 2005

An implantable microphone that can be utilized as part of a totally implantable hearing aid is designed and implemented. The proposed microphone is implanted in the center of the pinna, and designed to ensure the speech frequency range and the appropriate sensitivity. The characteristics of the proposed microphone are evaluated using a finite element analysis (FEA). The microphone is composed of a small electric condenser microphone, titanium case 6.2mm in diameter and 3mm high, and $10{\mu}m$ SUS316L vibrating membrane in contact with hypodermic tissue to maintain the sensitivity of the microphone. The microphone components are all made of biocompatible materials, then the assembled microphone is hermetically sealed using a polymer and ceramic. Experiments with the fabricated microphone confirm an operational bandwidth of up to 5kHz without any decline of sensitivity in 6mm of hypodermic tissue.

• 자원환경지질
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• 제53권3호
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• pp.259-269
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• 2020

The use of the geophysical method in mining prospecting has been studied in the Asdaf region (South-East of Morocco). The objective of the study is to examine the aptitude of the electrical technique, in this case induced polarization (IP) and electric tomography, combined with the electromagnetic method (VLF), in the exploration of barite . The result obtained by the pseudo-sections of electrical tomography and that of KH filtration highlighted anomalies of resistant contact (greater than 400Ω.m) and of high charge chargeability (5mV / V). These contacts are hosted in less resistant Devonian age shale and sandstone. The resistivity response obtained at their level is characteristic of the venous structures associated with barite mineralization. The direction of the mineralized veins is parallel to the direction of the fractured zones (NE-SW), which indicates that the mineralization in place is due to the tectonic movements of the Hercynian orogeny (from Devonian to Permian). These veins are aligned with the locations of abandoned mine shafts and with surface mining areas. Geophysical technique therefore seems to play a key role in barite mining exploration.

• Design & Manufacturing
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• 제10권1호
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• pp.41-45
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• 2016

Electrical equipment in factories, buildings, etc. with the development of the industry has become a large capacity. By the development, electric load also become diversified and there is also highly functional requirements being electrical equipment. Particularly in the small and medium-sized circuit breakers, tend to preferentially consider the economy stands out and improvements in safety, ease of mounting and connection through the modularity of the basic dimensions compact and cost to block expansion of the scope of the development of capacity, etc. The product having a competitive has been strongly required. In order to implement the circuit breakers of breaking capacity and compact at the same time taking into account the economic development of this technology applied to the current-limiting mechanism is essential budget or the current limiting mechanism is currently available mechanisms applicable to small and medium-sized frame (frame) can not do it. In this paper, at the same time satisfying the economic efficiency, by minimizing the load force of the moving contactor (moving contactor) to be applied to small and medium frame other hand to secure the economical efficiency without using high speed contact parting acceleration of the moving contactor conventional current-limiting mechanism, and to develop a current-limiting mechanism that can be satisfied with the same or higher performance to meet the needs of the market.

• 한국전기전자재료학회논문지
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• 제19권9호
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• pp.818-824
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• 2006

The effects of high-temperature process required to fabricate the SiC devices on the surface morphology and the electrical characteristics were investigated for 4H-SiC Schottky diodes. The 4H-SiC diodes without a graphite cap layer as a protection layer showed catastrophic increase in an excess current at a forward bias and a leakage current at a reverse bias after high-temperature annealing process. Moreover it seemed to deviate from the conventional Schottky characteristics and to operate as an ohmic contact at the low bias regime. However, the 4H-SiC diodes with the graphite cap still exhibited their good electrical characteristics in spite of a slight increase in the leakage current. Therefore, we found that the graphite cap layer serves well as the protection layer of silicon carbide surface during high-temperature annealing. Based on a closer analysis on electric characteristics, a conductive surface transfiguration layer was suspected to form on the surface of diodes without the graphite cap layer during high-temperature annealing. After removing the surface transfiguration layer using ICP-RIE, Schottky diode without the graphite cap layer and having poor electrical characteristics showed a dramatic improvement in its characteristics including the ideality factor[${\eta}$] of 1.23, the schottky barrier height[${\Phi}$] of 1.39 eV, and the leakage current of $7.75\{times}10^{-8}\;A/cm^{2}$ at the reverse bias of -10 V.

• Carbon letters
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• 제21권
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• pp.16-22
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• 2017

Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/$SiO_2$ substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ${\Delta}t_{DEP}$ 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/$SiO_2$/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity ($H_C$) and demonstrate increasing magnetization on saturation ($M_{SAT}$) and electric signal proportional to remanence ($M_r$), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.

• 한국세라믹학회지
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• 제50권6호
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• pp.498-503
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• 2013

Over the past decade, the feasibility of using ink-jet printing for the decoration of porcelain tiles has been explored, and significant advances have been made regarding the technologies underlying printing system and materials. An ink-jet printing system for porcelain tiles has many advantages compared with a conventional printing system, including the following: (1) it is a digital process; (2) it uses non-contact printing; (3) it allows random image generation; (4) it is a highly efficient process (reduced production cost); (5) it offers massive and continuous production; and (6) it uses inorganic pigment colorants. For these reasons, ink-jet printing systems for porcelain tiles have been commercialized and are at present rapidly spreading toceramics-leading countries such as Spain, Italy, China and Japan. We also developed a proprietary system involving a piezo-electric drop-on-demand method and an ink-circulation step. The resolution of this system is greater than 360 dpi after a heat treatment and the maximum printable width is 600 mm, even when setting the printing head unit with four digital colors (cyan, magenta, yellow, and black). In addition, we systematically developed ceramic colorant-containing inks and tile-printing technology applicable to our ink-jet printing system.