• 대한토목학회논문집
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• 제37권1호
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• pp.217-229
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• 2017

보의 표면에 부착된 압전웨이퍼를 통해 가진되고 측정되는 고주파수 대역의 전기역학적 신호는 보에 발생한 미세 손상에 매우 민감하다. 이러한 부착형 압전웨이퍼의 장점을 이용한 보의 손상 진단을 효과적으로 수행하기 위해서는 압전웨이퍼의 탐지범위 예측이 필요하다. 고주파수 대역에서 압전웨이퍼의 탐지범위에 영향을 주는 여러 가지 요인 중 가장 지배적인 인자는 보의 감쇠이다. 이 연구에서는 보에 부착된 압전웨이퍼의 전기역학적 신호를 이용하여 보의 감쇠를 추정할 수 있는 기법을 제시한다. 공진이 발생하는 과정에서 보의 감쇠효과를 고려하여 압전웨이퍼의 전기역학적 신호를 파전달 관점에서 정식화한다. 실제 계측된 전기역학적 신호로부터 구한 측정 감쇠비 함수값과 정식화된 전기역학적 신호로부터 계산된 감쇠비 함수값의 차이를 최소화하는 최소자승법을 통해 보의 감쇠비를 추정한다. 제시된 방법을 압전웨이퍼가 병치되어 있는 알루미늄 보 수치 및 실험 예제에 적용하여 타당성을 검증한다.

• 한국태양에너지학회 논문집
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• 제40권5호
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• pp.35-45
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• 2020

Photovoltaic (PV) power system prices have been steadily dropping in recent years due to their mass production and advances in relevant technology. Crystalline silicon (c-Si wafers) account for the largest share of the price of solar cells; reducing the thickness of these wafers is an essential part of increasing the price competitiveness of PV power systems. However, reducing the thickness of c-Si wafers is challenging; typically, phenomena such as bowing and cracking are encountered. While several approaches to address the bowing phenomenon of the c-Si solar cells exist, the only method to study the crack phenomenon (related to the strength of the c-Si solar cells) is the bending test method. Moreover, studies on determining the strength properties of the solar cells have focused largely on c-Si wafers, while those on the strength properties of front and rear-side electrodes and SiNx, the other components of c-Si solar cells, are scarce. In this study, we analyzed the strength characteristics of each layer of c-Si solar cells. The strength characteristics of the sawing mark direction produced during the production of c-Si wafers were also tested. Experiments were conducted using a 4bending tester for a specially manufactured c-Si solar cell. The results indicate that the back side electrode is the main component that experienced bowing, while the front electrode was the primary component regulating the strength of the c-Si solar cell.

• 폴리머
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• 제26권5호
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• pp.670-679
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• 2002

1, 3-bis[2-chloroethyl]-1-nitrosourea (BCNU, carmustine)는 악성 뇌종양 치료를 위하여 화학요법적 임상에서 널리 사용되는 약물이다. 또한, poly(D,L-lactide-co-glycolide) (PLGA, 분자량: 20000 g/mole, 락타이드와 글리콜라이드 몰비 75 : 25)는 약물전달시스템을 위한 약물 전달체로써 사용되어지는 잘 알려진 생분해성 초분자이다. 본 연구에서 폴리비닐피롤리돈 (PVP) 또는 폴리에틸렌옥사이드 (PEO)를 함유하고 있는 BCNU 함유 PLGA 웨이퍼들의 BCNU 방출거동과 웨이퍼에 포접된 친수성 고분자의 효과를 조사하였다. 친수성 고분자의 첨가 또는 첨가 없이 BCNU 함유 PLGA 미분말은 분사건조법에 의해 제조하였으며, 제조된 BCNU 함유 PLGA 미분말은 압축성 형법에 의해 웨이퍼형태고 제조하였다. 친수성 고분자가 첨가된 BCNU 함유 PLGA 미분말의 포접율은 85∼97%였고, PLGA에 포접된 BCNU의 결정성은 현저히 감소하였다. 약물 방출 경향과 분해 거동에서 친수성 고분자의 함량이 증가할수록 BCNU의 초기방출량과 방출속도는 증가됨을 확인하였다. 방출시험 기간동안 웨이퍼의 형태변화와 무게변화를 측정함으로써 친수성 고분자의 함량이 증가할수록 PLGA의 수차와 분해가 촉진됨을 관찰하였다.

• 설비공학논문집
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• 제16권5호
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• pp.475-481
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• 2004

This paper presents a force model of the clean tube system, which was developed as a means of transferring air-floated wafers inside a closed tube filled with super clean air. The recovering force from the holes for floating wafers is modeled as a linear spring and thus the wafers motion is modeled as a mass-spring-damper system. The propelling forces are modeled as linear along with the wafer location. The paper also proposes a control method to emit and stop a wafer at the center of a control unit. It reveals the minimum value of the propelling force to leave from the control unit. In order to stop the wafer, it utilizes the exact time when the wafer arrives at the position to activate the propelling force. Experiments with the clean tube system built for the 12 inch wafer shows the validity of the proposed model and the algorithm.

• 산업공학
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• 제23권3호
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• pp.229-238
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• 2010

Virtual metrology (VM), a critical component of semiconductor manufacturing, is an efficient way of assessing the quality of wafers not actually measured. This is done based on a model between equipment sensor data (obtained for all wafers) and the quality characteristics of wafers actually measured. This paper considers principal component regression (PCR), partial least squares regression (PLSR), kernel PCR (KPCR), and kernel PLSR (KPLSR) as VM models. For each regression model, two cases are considered. One utilizes all explanatory variables in developing a model, and the other selects significant variables using the genetic algorithm (GA). The prediction performances of 8 regression models are compared for the short- and long-term etch process data. It is found among others that the GA-KPLSR model performs best for both types of data. Especially, its prediction ability is within the requirement for the short-term data implying that it can be used to implement VM for real etch processes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1501_1502
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• 2009

Plasma treatment time was optimized to maximize the bonding strength between silicon and quartz. Bonding strength between the silicon and quartz is related to a surface energy which can be calculated by contact angle measurement. It was found that optimized time to get maximized surface energy was 15 sec. Silicon and quartz wafers were treated with $O_2$ plasma under different time splits and then bonded together. Bonding strength of the bonded wafers was measured by shear test. It was verified that the highest bonding strength was obtained when the silicon and quartz wafers were treated for 15 seconds. The maximum bonding strength exceeded the fracture strength of silicon.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.105-109
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• 2000

Micronization of sensor is a trend of the silicon sensor development with regard to a piezoresistive silicon pressure sensor the size of the pressure sensor diaphragm have become smaller year by year and a microaccelerometer with a size less than 200-300${\mu}m$ has been realized. In this paper we study some of the micromachining processes of SOI(silicon on insulator)for the microaccelerometer and their subsequent processes which might affect thermal loads. The finite element method(FEM) has been a standard numerical modeling technique extensively utilized in structural engineering discipline for design of SOI wafers. Successful thermal behaviors analysis and design of the SOI wafers based on the tunneling current concept using SOI wafer depend on the knowledge abut normal mechanical properties of the SCS(single crystal silicon)layer and their control through manufacturing process

• Transactions on Electrical and Electronic Materials
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• 제4권3호
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• pp.29-33
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• 2003

Tri-crystalline silicon wafers have three different orientations and three-grain boundaries. In this paper, tri-crystalline silicon (tri-Si) wafers have been used for the fabrication of buried contact solar cells. The optical and micro-structural properties of these cells after texturing in KOH solution have been investigated and compared with those of cast mult- crystalline silicon (multi-Si) wafers. We employed a cost effective fabrication process and achieved buried contact solar cell (BCSC) energy conversion efficiencies up to $15\%$ whereas the cast multi-Si wafer has efficiency around $14\%$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.81-84
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• 1995

A reliable bonding between two silicon wafers, regularly grooved and non-grooved, was done by the direct boning technology, It is Presented that high structural duality was realized not only at the bended interface but in the bulk, commensurate with the filling of artificial grooves, which would be attributed to the dislocation-gettering capability of groove free-surfaces during annealing. The groove filling would be explained with mass-transport phenomena assisted by the dislocation movement from initial contact boundaries toward groove surfaces. Intrinsic voids can be easily removed by aid of the grooves. The proposed method yielded also an intimate bonding not only between {111} wafers strongly misoriented and slightly inclined to {111} basal plane but even between {111} and {100} orientation wafers.

• 한국결정성장학회지
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• 제23권3호
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• pp.119-123
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• 2013

Most of the world's solar cells in photovoltaic industry are currently fabricated using crystalline silicon. Czochralski-grown silicon crystals are more expensive than multicrystalline silicon crystals. The future of solar-grade Czochralski-grown silicon crystals crucially depends on whether it is usable for the mass-production of high-efficiency solar cells or not. It is generally believed that the main obstacle for making solar-grade Czochralski-grown silicon crystals a perfect high-efficiency solar cell material is presently light-induced degradation problem. In this work, the substitution of boron with gallium in p-type silicon single crystal is studied as an alternative to reduce the extent of lifetime degradation. The diamond-wire sawing technology is employed to slice the silicon ingot. In this paper, the quality of the diamond wire-sawn gallium-doped silicon wafers is studied from the chemical, electrical and structural points of view. It is found that the characteristic of gallium-doped silicon wafers including texturing behavior and surface metallic impurities are same as that of conventional boron-doped Czochralski crystals.