• 대한수학회보
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• 제44권3호
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• pp.429-438
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• 2007

In this paper, we study the position vectors of a spacelike W-curve (or a helix), i.e., curve with constant curvatures, with spacelike, timelike and null principal normal in the Minkowski 3-space $\mathbb{E}_1^3$. We give some characterizations for spacelike W - curves whose image lies on the pseudohyperbolical space $\mathbb{H}_0^2$ and Lorentzian sphere $\mathbb{S}_1^2$ by using the positions vectors of the curve.

• 한국방사선학회논문지
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• 제14권4호
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• pp.391-396
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• 2020

본 연구는 Gd₂O₂S:Tb 형광체 화합물을 사용하여 비파괴검사 중 방사선투과검사에 적용할 수 있는 형광체 증감지를 개발하였다. 또한 이러한 형광체 증감지를 FE-SEM, RMS 및 RDS 분석을 통해 형광체 증감지의 영상 균일도를 분석하였다. 또한, 응력-변형 특성 곡선 측정을 통해 Gd₂O₂S:Tb 형광체 스크린의 인장강도, 신장률 및 탄성계수를 평가하였다. 실험 결과, RSD 값이 평가 기준인 10% 이내로 우수한 영상균일도를 가지는 것으로 평가되었다. 또한, 물리적 특성 평가 결과, 인장 강도는 1.1760 N/㎟이며, 파단시 인장강도는 1.1515 N/㎟로 나타났다. 이러한 결과로부터 본 연구에서 제작된 상온 겔-프린팅 제조법을 이용하여 제작된 Gd₂O₂S:Tb 형광체 스크린은 방사선 투과검사용 디지털 방사선 검출기에 적용이 가능할 것으로 사료된다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.255-257
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• 2004

This report presents S-N testing results of the butt and T-joint weldment which are produced by single sided welding with cenramic backing material. The specimen is designed in accordance with JISZ 3103 aid the test is peformed by the JSME S002. The nominal and hot spot stress based design S-N curves derived from fatigue tests are compared with the BS design curve. For butt and T-joint, it can be known that the double-sided butt welding process could be replaced by the single sided butt welding.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.357-361
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• 2016

Si와 InAs 두 가지 채널 물질을 가지고 3가지 수송 방향 <100>, <110>, <111>으로 변화시키며 각각의 Nanowire nMOSFETs을 가지고 ballistic quantum transport simulation을 진행하였다. 각각의 경우에 대해 E-k curve를 구한 다음에 band curvature로 캐리어의 유효질량을 계산하고, 이를 통해 MOSFET의 전류 세기를 결정짓는 DOS와 carrier injection velocity를 구하여 어떤 경우에 가장 높은 ON-current를 흐르게 하는지 확인해 보았다. 하지만 예상과 달리 나노와이어의 직경이 1.4nm으로 매우 작기 때문에 valley-splitting이 일어나 Si<110>의 경우에 가장 작은 캐리어 유효 질량을 갖고 있는 사실을 확인할 수 있었다. 결론적으로 Si<100>의 경우에 trade-off 관계에 있는 DOS와 carrier injection velocity가 6가지 경우 중 최적의 조합을 가짐으로써 가장 높은 ON-current를 흐르게 하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.305-306
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.401-402
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• 2008

• 생물정신의학
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• 제27권2호
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• pp.94-100
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• 2020

Objectives Amyloid β positron emission tomography (Aβ PET) is widely used as a diagnostic tool in patients who have symptoms of cognitive impairment, however, this diagnostic examination is too expensive. Thus, predicting the positivity of Aβ PET before patients undergo the examination is essential. We aimed to analyze clinical predictors of patients who underwent Aβ PET retrospectively, and to develop a predicting model of Aβ PET positivity. Methods 468 patients who underwent Aβ PET with cognitive impairment were recruited and their clinical indicators were analyzed retrospectively. We specified the primary outcome as Aβ PET positivity, and included variables such as age, sex, body mass index, diastolic blood pressure, systolic blood pressure, education, dementia family history, Mini Mental Status Examination (MMSE), Clinical Dementia Rating (CDR), Clinical Dementia Rating-Sum of Box (CDR-SB), hypertension (HTN), diabetes mellitus (DM) and presence of apolipoprotein E (ApoE) E4 as potential predictors. We developed three final models of amyloid positivity prediction for total subjects, mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia using a multivariate stepwise logistic regression analysis. Receiver operating characteristic (ROC) curve analysis was performed and the area under curve (AUC) value was calculated for the ROC curve. Results Aβ PET negative patients were 49.6% (n = 232), and Aβ PET positive patients were 50.4% (n = 236). In the final model of all subjects, older age, female sex, presence of ApoE E4 and lower MMSE are associated with Aβ PET positivity. The AUC value was 0.296. In the final model of MCI subjects (n = 244), older age and presence of ApoE E4 are associated with Aβ PET positivity. The AUC value was 0.725. In the final model of AD subjects (n = 173), lower MMSE scores, the presence of ApoE E4 and history of HTN are associated with Aβ PET positivity. The AUC value was 0.681. Conclusions The cerebral amyloid positivity model, which was based on commonly available clinical indicators, can be useful for prediction of amyloid PET positivity in MCI or AD patients.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.753-756
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• 1992

The piezoelectric ceramics of PMS-PZT was made in the radial mode disk. As the results, in the application of filter required conditions: that is, higher-values for piezoelectric properties($K_p$, $Q_m$) and lower-values for stabilities of $F_{\tau}$(temp. coefficient, aging rate), 5PMS-51PT-44PZ composition statified well. This composition was made in the dot-ring type. Asthe results, with increasing $n^2$ both $Q_m$ and S had high values, decreasing $n^2$ both $K_p$ and BW had low values when the diameter of sintered bodies were constant. Therefore, curve of filter characteristic have sharped with increasing $n^2$ and BW broadened with decreasing $n^2$.

• 대한기계학회논문집
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• 제12권4호
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• pp.760-780
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• 1988

본 연구에서는 변동하중하의 피로수명 예측법에 관하여 미국 자동차공학회 (SAE) 피로손상분과의 광범위한 연구결과를 이용하여, 거시적인 피로균열 발생까지의 수명을 대상으로 검토한 것이다. 특히 현장에서 많이 직면하는, 재료의 피로특성에 관한 데이터가 거의 없는 경우에 대해서도 검토하고 있다.

• 한국수학교육학회지시리즈A:수학교육
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• 제25권3호
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• pp.77-100
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• 1987

Let G : R$^n$${\times}$R\longrightarrowR$^n$ be defined by a Homotopy solving a system F($\chi$)=0 of nonlinear equations. For the vector v$\^$k/ with G'(u$\sub$k/)v$\^$k/=0, ∥v$\^$k/∥=1 where uk is one point in Zero Curve let u$\sub$0/$\^$k/=v$\^$k/＋$\tau$v$\^$k/ be the first prediction for the next point u$\^$k+1/, $\tau$$\in$(0, 1). When u$\sub$0/$\^$k/ approaching too losely to some unwanted point. to follow the Zero Curve may occur the returning or cycling. One lion for it is discussed and tile parametrizied Homotopy algorithm for solving F($\chi$)=0 with it been established. Also some theorems by means of the regular value have been discussed for Zero Curves of G(u)=0 and some theorems for algorithm have been obtained.