• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.73-73
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• 2000

안티퓨즈 소자는 프로그램 가능한 절연층의 상하 각각에 금속층이나 다결정 실리콘 등의 전도 가능한 전극으로 구성된다. 프로그램은 상하 전극간에 임계전압을 가했을 때 일어나게 되며 이때 절연층이 파괴되므로 비가역적이어서 재사용은 불가능하게 된다. 안티퓨즈 소자는 이러한 프로그램 특성으로 인하여 메모리 소자를 이용한 스위치 보다 속도나 집적도 면에서 우수하다. FPGAsdp 사용되는 안티퓨즈 소자는 집적도의 향상과 적정 절열파괴전압 구현을 위해 절연막의 두께를 감소시키는 것이 바람직하다. 그러나 두께나 감소될 경우 바닥전극의 hillock에 큰 영향을 받게 되며, 그로 인해 절연막의 두께를 감소시키는 것는 한계가 있는 것으로 보고되어 있다. 본 논문에서는 낮은 구동 전압에서 동작하고 안정된 on/pff 상태를 갖는 Al/TiO2-SiO2/Mo 형태의 안티퓨즈 소자를 제안하였다. 만들어진 antifuse cell은 0.6cm2 크기로 약 300개의 샘플을 제작하여 측정하였다. 비저항이 6-9 $\Omega$-cm인 P형의 실리콘 웨이퍼에 RF 마그네트론 스퍼터링(RF magnetron sputtering) 방법으로 하부전극인 Mo를 3000 증착하였다. SiO2는 안티퓨즈에서 완충막의 역할을 하며 구조적으로 antifuse cell을 완전히 감싸고 있는 형태로 제작되었다. 완충막 구조를 만들기 dln해 일반적인 포토리소그라피(Photo-lithography)작업을 거처 형성하였다. 형성된 hole의 크기는 5$mu extrm{m}$$\times$5$\mu\textrm{m}$ 이었다. 완충막이 형성된 기판위에 안티퓨즈 절연체인 SiO2를 PECVD 방식으로 100 증착하였다. 그 후 이중 절연막을 형성시키기 위해 LPCVD를 이용하여 TiO2를 150 증착시켰다. 상부 전극은 thermal evaporation 방식으로 Al을 250nm 증착하여Tejk. 하부전극으로 사용된 Mo 금속은 표면상태가 부드럽고 녹는점이 높은 매우 안정된 금속으로, 표면위에 제조된 SiO2의 특성을 매우 안정되게 유지시켰다. 제안된 안티푸즈는 이중절연막을 증착함으로서 전체적인 절연막의 두께를 증가시켜 바닥전극의 hillock의 영향을 적게 받아 안정성을 유지할 수 있도록 하였다. 또한, 두 절연막 사이의 계면 반응에 의해 SiO2 막을 약화시켜 절연막의 두께가 두꺼워졌음에도 기존의 SiO2 절연막의 절연 파괴 전압 및 누설 전류오 비교되는 특성을 가졌다. 이중막을 구성하고 있는 안티퓨즈의 ON-저항이 단일막과 비교해 비슷한 것을 볼 수 잇는데, 그 이유는 TiO2에 포함된 Ti가 필라멘트에 포함되어 있어 필라멘트의 저항을 감소시켰기 때문으로 사료된다. 결국 이중막을 구성시 ON-저항 증가에 의한 속도 저하 요인은 없다고 할 수 있다. 5V의 절연파괴 시간을 측정한느 TDDB 테스트 결과 1.1$\times$103 year로 기대수치인 수십 년보다 높아 제안된 안티퓨즈의 신뢰성을 확보 할 수 있었다. 제안된 안티퓨즈의 이중 절연막의 두께는 250 이고 프로그래밍 전압은 9.0V이고, 약 65$\Omega$의 on 저항을 얻을수 있었다.

• Clean Technology
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• v.25 no.3
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• pp.206-222
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• 2019

Recently, various multiphase flows have been developed, and among them some models have been commercialized. However, most of them have been developed based on a pressure-based approach; therefore, various numerical difficulties were involved inherently. Accordingly, in order to overcome these numerical difficulties, a multiphase flow model, MultiPhaSe flow (MPS), following a fractional-flow based approach was developed. In this study, by combining a contaminant transport module describing an enhanced dissolution effect of a surfactant with MPS, a MultiPhaSe flow and TranSport (MPSTS) model was developed. The developed model was verified using the analytical solution of Clement. The MPSTS model can simulate the process of surfactant enhanced aquifer remediation including interphase mass transfer and contaminant transport in multiphase flow by using the coupled particle tracking method and Lagrangian-Eulerian method. In this study, a surfactant was used in a non aqueous phase liquid (NAPL) contaminated area, and the effect of hydro-geological heterogeneity in the layered media on remediation efficiency was studied using the developed model. According to the numerical simulation, when hydraulic conductivity in a lower layer is 10 times, 20 times, and 50 times larger than that in an upper layer, the concentration of dissolved diesel in the lower layer is much higher than that in the upper layer because the surfactant moves faster along the lower layer owing to preferential flow; thus, the surfactant enhances dissolution of residual non aqueous phase liquid in the lower layer.

• Science of Emotion and Sensibility
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• v.25 no.1
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• pp.67-78
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• 2022

Interest in bio-signal monitoring of wearable devices is increasing significantly as the next generation needs to develop new devices to dominate the global market of the information and communication technology industry. Accordingly, this research developed a resistive textile strain sensor through a wetting process in a single-wall carbon nanotube dispersion solution using an E-Band with low hysteresis. To measure the resistance signal in the E-Band to which electrical conductivity is applied, a universal material tester, an Arduino, and LCR meters that are microcontroller units were used to measure the resistance change according to the tensile change. To effectively handle various noises generated due to the characteristics of the fabric textile strain sensor, the filter performance of the sensor was evaluated using the moving average filter, Savitsky-Golay filter, and intermediate filters of signal processing. As a result, the reliability of the filtering result of the moving average filter was at least 89.82% with a maximum of 97.87%, and moving average filtering was suitable as the noise filtering method of the textile strain sensor.

• Maritime Security
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• v.1 no.1
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• pp.215-240
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• 2020

In 2017, the U.S. DARPA coined 'mosaic warfare' as a new way of warfighting. According to the Timothy Grayson, director of DARPA's Strategic Technologies Office, mosaic warfare is a "system of system" approach to warfghting designed around compatible "tiles" of capabilities, rather than uniquely shaped "puzzle pieces" that must be fitted into a specific slot in a battle plan in order for it to work. Prior to cover mosaic warfare theory and recent development, it deals analyze its background and several premises for better understanding. The U.S. DoD officials might acknowledge the current its forces vulnerability to the China's A2/AD assets. Furthermore, the U.S. seeks to complete military superiority even in other nation's territorial domains including sea and air. Given its rapid combat restoration capability and less manpower casualty, the U.S. would be able to ready to endure war of attrition that requires massive resources. The core concept of mosaic warfare is a "decision centric warfare". To embody this idea, it create adaptability for U.S. forces and complexity or uncertainty for the enemy through the rapid composition and recomposition of a more disag g reg ated U.S. military force using human command and machine control. This allows providing more options to friendly forces and collapse adversary's OODA loop eventually. Adaptable kill web, composable force packages, A.I., and context-centric C3 architecture are crucial elements to implement and carry out mosaic warfare. Recently, CSBA showed an compelling assessment of mosaic warfare simulation. In this wargame, there was a significant differences between traditional and mosaic teams. Mosaic team was able to mount more simultaneous actions, creating additional complexity to adversaries and overwhelming their decision-making with less friendly force's human casualty. It increase the speed of the U.S. force's decision-making, enabling commanders to better employ tempo. Consequently, this article finds out and suggests implications for Korea armed forces. First of all, it needs to examine and develop 'mosaic warfare' in terms of our security circumstance. In response to future warfare, reviewing overall force structure and architecture is required which is able to compose force element regardless domain. In regards to insufficient defense resources and budget, "choice" and "concentration" are also essential. It needs to have eyes on the neighboring countries' development of future war concept carefully.

• Journal of Chest Surgery
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• v.38 no.3 s.248
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• pp.214-220
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• 2005

Extended transseptal approach can provide an excellent view of the mitral valve but the safety of this approach is controversial because this incision requires transaction of the sinus node artery, which in most cases and can result postoperative arrhythmia. The purpose of this study was to evaluate perioperative and longterm conduction disturbances and the cardiac rhythms of patients who underwent an extended transseptal approach for mitral valve surgery. Material and Method: Postoperative cardiac rhythms were analyzed in the 164 consecutive patients who received mitral valve replacements with a extended transseptal approach between March 1992 and July 2003. Result: Of the 84 patients in normal sinus rhythm, 34 ($39\%$) had developed transient junctional rhythm and atrial fibrillation after operation, lasting less than 72 hours in most of cases. No intractable arrhythmias occurred. Most of these arrhythmia were not detected at the time of discharge and only 8 patients ($9\%$) had atrial fibrillation at discharge. Postoperative PR intervals increased for 1 week, then decreased within 2 weeks postoperatively, and returned to normal range by 6 months postoperatively. During the postoperative period, 4 of the 78 patients with preoperative atrial fibrillation developed normal sinus thythm. Conclusion: The post-operative arrhythmias were temporary and showed no significant complications after extended transseptal approach for the mitral valve surgery.

• Journal of the Korean Society of Radiology
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• v.4 no.1
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• pp.5-9
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• 2010

In recent, a digital x-ray detector attracted worldwide attention and there are many studies to commercialize. There are two methods in digital x-ray detector. This method is an Indirect method and Direct method. This study is to see the differences between the digital x-ray detector based on a-Se used in the existing indirect conversion method and an x-ray conversion material that has better SNR(Signal-to-noise ratio) and property than the a-Se. To solve the problem that is difficult to make a large area film using Screen-Print method, we used a Screen-Print method. In this study, we used a polyclystal $HgI_2$ as x-ray conversion material and a sample thickness is $150{\mu}m$ and an area is $3cm{\times}3cm$. ITO(Indium-Tin-Oxide) electrode was used as top electrode using a Magnetron Sputtering System and each area is $3cm{\times}3cm$, $2cm{\times}2cm$ and $1cm{\times}1cm$ and then we evaluated darkcurrent, sensitivity and SNR of the $HgI_2$ film are measured, then we evaluated the electrical properties. And we used a current integration mode when I-V test. This experiment shows that the sensitivity increases in accordance with the area of the electrode but the SNR is decreased because of the high darkcurrent. Through fabricating of various thicknesses and optimal electrodes, we will optimize SNR in the future work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.152-161
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• 2023

In general, large-capacity hydrogen storage vessels, typically in the form of vertical cylindrical vessels, are constructed using steel materials. These vessels are anchored to foundation slabs that are specially designed to suit the environmental conditions. This anchoring method involves pre-installed anchors on top of the concrete foundation slab. However, it's important to note that such a design can result in concentrated stresses at the anchoring points when external forces, such as seismic events, are at play. This may lead to potential structural damage due to anchor and concrete damage. For this reason, in this study, it selected an vertical hydrogen storage vessel based on site observations and created a 3D finite element model. Artificial seismic motions made following the procedures specified in ICC-ES AC 156, as well as domestic recorded earthquakes with a magnitude greater than 5.0, were applied to analyze the structural behavior and performance of the target structures. Conducting experiments on a structure built to actual scale would be ideal, but due to practical constraints, it proved challenging to execute. Therefore, it opted for an analytical approach to assess the safety of the target structure. Regarding the structural response characteristics, the acceleration induced by seismic motion was observed to amplify by approximately ten times compared to the input seismic motions. Additionally, there was a tendency for a decrease in amplification as the response acceleration was transmitted to the point where the centre of gravity is located. For the vulnerable components, specifically the sub-system (support columns and anchorages), the stress levels were found to satisfy the allowable stress criteria. However, the concrete's tensile strength exhibited only about a 5% margin of safety compared to the allowable stress. This indicates the need for mitigation strategies in addressing these concerns. Based on the research findings presented in this paper, it is anticipated that predictable load information for the design of storage vessels required for future shaking table tests will be provided.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.45-55
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• 2006

A 2-D unconfined flow model is developed to analyze annual variations of groundwater level and bank filtration rate (BFR) for an experimental riverbank filtration site in Koryeong, Korea. Two types of boundary conditions are examined for the river boundary in the conceptual model: the static head condition that uses the average water level of the river and the dynamic cyclic condition that incorporates annual fluctuation of water level. Simulations show that the estimated BFR ranges $74.3{\sim}87.0%$ annually with the mean of 82.4% for the static head boundary condition and $52.7{\sim}98.1%$ with the mean of 78.5% for the dynamic cyclic condition. The results illustrate that the dynamic cyclic condition should be used for accurate evaluation of BFR. Simulations also show that increase of the distance between the river and the pumping wells slightly decreases BFR up to 4%, and thereby indicate that it is not a critical factor to be accounted for in designing BFR of the bank filtration system. A sensitivity analysis is performed to examine the effects of model parameters such as hydraulic conductivity and specific yield of the aquifer, recharge rate, and pumping rate. The results demonstrate that the average groundwater level and BFR are most sensitive to both the pumping rate and the recharge rate, while the water level of the pumping wells is sensitive to the hydraulic conductivity and the pumping rate.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.82.1-82.1
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• 2010

수소화된 비정질 실리콘 박막을 이용한 반도체는 현재 태양전지, 트랜지스터, 매트릭스 배열 및 이미지 센서 등의 분야에서 이용되고 있다. 자세히 이야기 하면, 여러 가지의 광전효과 물질에 대한 특성이 있으며, 가시광선영역에 대하여 > $10^5cm^{-1}$이상의 매우 높은 광흡수계수와 낮은 온도를 갖는 증착공정 등이 있다. 박막의 밴드갭은 약 1.6~1.8eV로서 태양전지의 흡수층과 passivation층으로 적절하다. 여러 가지 종류의 태양전지 중 비정질 실리콘 박막/결정질 실리콘 기판의 구조로 이루어진 이종접합 태양전지는 저온에서 공정이 가능한 대표적인 것으로서 HIT(Heterojunction with Intrinsic Thin layer)구조로 산요사에 의해 제안된 것이다. 이것은 결정질 실리콘 기판과 도핑된 비정질 실리콘 박막사이에 얇은 진성층 비정질실리콘 박막을 삽입함으로서, 캐리어 전송을 좋게하여 실리콘 기판 표면의 passivation효과를 증대시키는 결과를 가지고 온다. 실험실 규모에서는 약 20%이상의 효율을 보이고 있으며, 모듈에서는 19.5%의 높은 효율을 보이고 있어 실리콘 기판을 이용한 고효율 태양전지로서 각광을 받고 있다. 이러한 이종접합 태양전지의 대부분은 단결정 실리콘을 사용하고 있는데, 점차적으로 다결정 실리콘 기판으로 추세가 바뀌고 있어, 여기에 맞는 표면 passivation 공정 및 분석이 필요하다. 본 발표에서는 다결정 실리콘 기판위에 진성층 비정질 실리콘 박막을 유도결합 플라즈마 화학기상 증착법(ICP-CVD)을 이용하여 제조하여 passivation 효과를 분석한다. 일반적으로 ICP는 CCP(coupled charged plasma)에 비해 약 100배 이상 높은 플라즈마 밀도를 가지고 있으며, 이온 충돌같은 표면으로 작용하는 것들이 기존 방식에 비해서 작다라는 장점이 있다. 먼저, 유리기판을 사용하여 ICP-CVD 챔버내에 이송 한 후 플라즈마 파워, 온도 및 가스비(SiH4/H2)에 따른 진성층 비정질 실리콘 박막을 증착 한 후, 밴드갭, 전도도 및 결합구조 등에 대한 결과를 분석한 후, 최적의 값을 가지고 250um의 두께를 갖는 다결정 실리콘을 기판위에 증착을 한다. 두께(1~20nm)에 따라 표면의 passivation이 되는 정도를 QSSPCD(Quasi steady state Photoconductive Decay)법에 의하여 소수캐리어의 이동거리, 재결합율 및 수명 등에 대한 측정 및 분석을 통하여 다결정 실리콘 기판의 passivation effect를 확인한다. 제시된 데이터를 바탕으로 향후 다결정 HIT셀 제조를 통해 태양전지 효율에 대한 특성을 비교하고자 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.4
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• pp.280-287
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• 2008

For the reduction of common-mode noise level in Indirect-contact ECG (IDC-ECG) measurement a driven-right-leg grounding method was a lied to the IDC-ECG. Because the IDC-ECG does not require any direct contact between the electrodes and the human skin. it is adequate for un-constraining long-term ECG measurement at home and its various applications are now under development. However, larger 60 Hz noise induced by power line a ears in IDC-BCG than in conventional ECG, that is a restriction of IDC-ECG a application. In this study, the driven-right-leg ground which has been used in conventional direct-contact ECG, was adapted to the IDC-ECG measurement by feedback of the inversion of amplified common-mode noise to the body through the conductive fertile laid on the chair seat By this study, indirect-contact driven-right-leg ground was developed and it was shown to work stably. It was shown that the level of 60Hz power line noise was reduced to about -40 dB when the driven-right-leg gain was 1000. This study shows that we can extend the upper limit of the frequency band of IDC-ECG to 100Hz from 30Hz which is conventional upper limit in IDC-ECG, and we can raise the ground impedance between the body and conductive textile. So it is expected that the application area of the IDC-ECG will be extended by the results of this study.