• 정보과학회 논문지
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• 제44권3호
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• pp.223-231
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• 2017

본 논문에서는 최근 광범위하게 사용되고 있는 멀티 코어 환경에서의 모바일 장치의 성능에 대하여 연구하였다. 이전에 연구되어왔던 멀티 코어의 성능에 대한 분석은, 대부분 데스크톱 PC에서의 분석이었고, heterogeneous 멀티 코어에 대한 분석방법이 충분하지 않았다. 이러한 문제점을 보완하고자 homogeneous 멀티 코어의 분석 방법을 응용한 heterogeneous 멀티 코어 환경에서 성능을 분석하는 방법을 제안하였다. 본 연구에서는 이를 분석하는 데 있어서 작업의 할당에는 Size Interval Task Allocation (SITA) 기법을 사용하였고, 코어에서의 처리 방법은 Shortest Remaining Processing Time (SRPT) 기법을 사용하였다. 이 중 SITA 기법에서 가장 중요한 분석인 cutoff point에 대한 새로운 계산 방법을 제안하였고, 이를 체류 시간을 계산하는 데 사용함으로써 계산의 용이성과 정확성을 높였다. 또한, ESESC 시뮬레이터에서의 측정을 통해 분석값과 측정값에 큰 차이가 없음을 확인하였다.

• 지질공학
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• 제11권1호
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• pp.81-99
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• 2001

터널의 차수그라우팅 효과를 확인하기 위하여 영천댐 도수터널 건설공사 중에 현장 그라우팅 시험을 수행하였다. 시험은 그라우팅 시기에 따라 굴착전, 굴착후 및 콘크리트 라이닝일 설치된 이후의 압밀 그라우팅 등으로 구분하였고, 주입재료, 암종 및 지질인자, 그라우팅공의 천공방향 및 주입단계에 따른 효과를 비교하도록 계획하였다. 재료의 특성에 따른 차수효과는 포틀랜드시멘트, 마이크로시멘트, 마이크로시멘트 마이크로시멘트+규산에 비해 우레탄이 가장 뛰어났으며, 시공시기에 따라서는 라이닝후 및 굴착후에 비해 굴착전 그라우팅시 차수효과가 뛰어났다. 암종에 따라서는 화산암 및 화강암지반에 비해 퇴적암지반에서 차수효과가 낮게 나타났는데 이는 퇴적암에 발달하는 절리틈새가 적고 절리 충전물이 많아서 주입재의 침투성 저조에 기인한 것으로 사료된다. RMR값과는 직접적인 상관성이 없으나 RMR 요소 중 절리틈의 간극이 클수록 차수효과가 높게 나타났다. 천공방향은 차수효과에 영향을 미치지 않았으나 주입방법은 천공 및 주입의 단계를 세분할 수록 높은 차수 효과를 기대할 수 있다.

• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.283-292
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• 1996

Objective: To determine the cutoff value of clomiphene citrate challenge test(CCCT) that can predict the normal and abnormal(diminished) ovarian response group and to assess the usefulness of CCCT as a predictor of ovarian reserve. Materials and Methods: From March 1994 to Februry 1996, CCCT was performed to 129 infertile patients and among them, 20 patients whose basal FSH on the third day of menstrual cycle was more than 20 mIU/ml were excluded. At the same time, the same CCCT was performed to the fifteen healthy volunteers with proven fertility to determine the cutoff value of CCCT. Results; 1) A FSH value higher than 23.4 mIU/ml, measured on the 10th day of menstrual cycle, was defined as a abnormal ovarian response. The cutoff value of 23.4 mIU/ml is more than 2 standard deviations(SD) above the mean value of 15 healthy women after CCCT. 2) The abnormal CCCT group, the subpopulation with a FSH value of 23.4 mIU/ml or more, was 7.3%(8/109) and their mean age was higher than the normal CCCT group($36.5{\pm}4.5$ vs. $32.9{\pm}4.8$, P = 0.059). And the percentage of the patients older than 35 years of the abnormal CCCT group was significantly higher than that of the normal CCCT group(62.5% vs. 38.6%, p <0.05). 3) There was no correlation between the hormone values of the third day and the 10th day of menstrual cycle before and after CCCT except between FSH of the third day and the 10th day. Conclusion: The CCCT is a good method to predict the individual ovarian response to COH for ART, especially in the patients who has no other abnormal findings that predict poor prognosis. And it is neccessary to determine the cutoff value of CCCT by the large numbers of randomized study, and combining the previously proven prognostic factors, it can be applicated in many individual centers for evaluate the ovarian response before ART program.

• 한국임상수의학회지
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• 제37권4호
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• pp.185-190
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• 2020

This retrospective, echocardiographic study using 144 dogs with clear systolic tricuspid regurgitation on Doppler echocardiography was performed to determine the diagnostic value of the systolic tricuspid regurgitation velocity/pulmonary artery flow velocity time integral to predict the Doppler estimates of dogs with tricuspid regurgitation pressure gradient compared with other cardiac indices of pulmonary hypertension, and to investigate a cutoff value to select patients with a potentially poor outcome. The systolic tricuspid regurgitation velocity/pulmonary artery flow velocity time integral increased significantly as the severity of pulmonary hypertension increased and had a correlation coefficient that was analogous to those of other conventional cardiac indices. A cutoff value greater 1.65 provided the best-balanced sensitivity (84%) and specificity (80%) in determining patients with a poor prognosis. In conclusion, the systolic tricuspid regurgitation velocity/pulmonary artery flow velocity time integral is readily obtained using routine echocardiography and could provide a non-invasive, novel, and supplementary index for evaluating dogs with pulmonary hypertension as useful prognostic criteria, particularly in those with advanced pulmonary hypertension.

• Current Optics and Photonics
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• 제1권3호
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• pp.207-213
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• 2017

The Adaptive Front-lighting System (AFS) is a part of the active safety system, providing optimized vision to the driver during night time and other poor-sight conditions of the road by automatic adaptation of lighting to environmental and traffic conditions. Basically, an AFS provides four different modes of the passing beam as designated in an United Nations Economic Commission for Europe regulation (ECE324-R123): neutral state or country light (Class C), urban light (Class V), highway light (Class E), and adverse weather light (Class W). In this paper, we first present an optics design for an AFS system capable of producing the Class C/V/E/W patterns requiring only on/off modulation of multi-array LEDs with no need for any additional mechanical components. The AFS optics consists of two separated modules, cutoff and spread; the cutoff module lights a narrow central area with high luminous intensity, satisfying the cutoff regulation, and the spread module forms a wide spread beam of low luminous intensity. Each module consists of two major parts; the first converts a discretely positioned LED array into a full-filled area emitting light source plane, and the second projects the light source plane to a 25 m away target plane. With the combination of these two optics modules, the four beam patterns are formed by simple on/off modulation of multi-array LEDs. Then we report the development of a prototype that was demonstrated to provide the four beam patterns.

• 전자공학회논문지C
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• 제35C권9호
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• pp.64-72
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• 1998

본 논문에서는 상보형 high swing cascode 전류미러를 이용하여 저전압, 저전력 구동이 가능하고 고주파수 응용이 가능한 전류 적분기를 설계하였다. 간단한 전류미러로 구성된 적분기는 적분기의 비 이상적인 입력, 출력 저항 때문에 출력 전류 오차가 발생하는데 제안된 전류 적분기는 출력 저항이 증가하여 출력 전류의 오차가 감소하였다. 설계된 무손실, 유손실 전류 적분기를 이용한 설계 예로 3차 버터워스 저역통과 필터를 개구리도약형으로 구현하였다. 필터 구현시 무손실 전류 적분기의 위상 추이 때문에 발생하는 차단주파수 부근에서의 크기 특성 왜곡을 predistortion 설계법을 이용하여 감소시켰다. 설계된 전류모드 필터를 0.8㎛ CMOS n-well 공정 파라미터를 이용하여 SPICE 시뮬레이션한 결과 단일 2V 공급 전압에서 차단주파수는 20MHz, 전력소모는 615㎼를 갖는다. 또한 필터의 차단주파수는 DC 바이어스 전류에 의해 동조 할 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.273-273
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• 2012

컷오프 진단법은 두 개의 탐침 형태로 제작된 마이크로 웨이브 진단법으로, 간단한 수식을 통해 전자밀도, 전자온도 등을 측정할 수 있다. 컷오프 탐침은 방사 안테나, 측정 안테나와 네트워크 분석기로 구성되어 있다. 네트워크 분석기는 두 안테나 사이의 플라즈마 투과 스펙트럼을 만드는데 쓰이며, 스펙트럼 분석을 통해 플라즈마 변수들을 측정할 수 있다. 이 진단법은 장치나 분석방법이 매우 간단한 장점을 지니며, 약 1 mW 정도의 적은 파워를 사용하여 플라즈마 상태를 거의 변화시키지 않는 측정이 가능하다. 또한 CF4와 같은 공정 가스를 이용한 플라즈마에서도 사용이 가능하다. 그러나 컷오프 진단법을 사용한 측정은 다른 종류의 진단법과 마찬가지로, 약 1초 정도의 긴 시간을 필요로 하는 단점이 있어, 펄스 플라즈마나 토카막과 같이 빠르게 변하는 플라즈마를 측정하기에는 무리가 있다. 최근에 개발된 푸리에 컷오프 탐침(Fourier Cutoff Probe, FCP)는 기존의 컷오프 탐침의 느린 시간분해능을 개선하기 위해 개발되었다. [1] 펄스 형태의 단일신호를 플라즈마를 투과하기 전후로 비교하면 투과 스펙트럼 및 플라즈마 변수들을 얻을 수 있으며, 기존 연구에서 구한 시간 분해능은 약 15 나노초였다. 이 값은 펄스 발생장치의 스펙에 따라 변하게 된다. 펄스폭이 짧을수록 시간분해능이 좋아지지만, 무한정 좋아질 수는 없다. 이 논문에서는 FCP 측정의 시간 분해능을 이론적으로 구하고, 시간 분해능의 이론적 한계를 구했다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1417-1422
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• 2003

An electrical cascade impactor is a multistage impaction device to separate airborne particles into aerodynamic size classes using electrical method. We designed a real-time three-stage electrical low-pressure impactor, which is proper to nanometer sized environmental aerosols. Performance evaluation was carried out for stage 1 and 2. The monodisperse liquid dioctyl sebacate (DOS) particles were generated using condensation-evaporation followed by electrostatic classification using DMA (differential mobility analizer) for particles with diameters in the range of $0.04{\sim}0.8{\mu}m$. The evaluation of the electrical impactor is based on the use of two electrometers, one connected to the impaction plate of the impactor, and the other to the faraday cage as backup filter. The results showed that the experimental 50% cutoff diameters in the operation pressure were 0.53 and $0.12{\mu}m$ for stage 1 and stage 2. The effect of operation pressure on the cutoff diameter and the steepness of collection effcieicy curves is investigated.

• 대한간호학회지
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• 제46권1호
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• pp.59-68
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• 2016

Purpose: Increase in suicide rate for senior citizens which has become widespread in our society today. It is not a normal social phenomenon and is beyond the danger level. The contents of this study include Korean senior citizens' suicide related risk factors and warning signs, and the development of a simple Geriatric Suicide Risk Scale. Methods: This study is Methodological Research to verify reliability and validity of the Geriatric Suicide Risk Scale according to the tool development process suggested by Devellis (2012). Results: For predictive validity assessment, high suicide screening accuracy was showed with an Area under the ROC curve (AUC) of .93. For the optimal cutoff point of 11, sensitivity was 93.9%, and specificity, 75.7% which are excellence levels. Cross validity for assessment of generalization possibility showed the Area under the ROC curve (AUC) as .82 and in case of a cutoff point of 11, sensitivity was 73.7%, and specificity, 65.9%. Conclusion: When it comes to practical nursing, it is significant that the Korean Geriatric Suicide Risk Scale has high reliability and validity through adequate tool development and the tool assessment step to select degree of suicide risk of senior citizens. Also, it can be easily applied and does not take a long time to administer. Further, it can be used by health care personnel or the general public.

• Journal of Astronomy and Space Sciences
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• 제35권4호
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• pp.219-225
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• 2018

Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of solar cycles 20-24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the solar cyclic modulation. During solar cycles 20-24, the maximum phase derived by harmonic analysis showed no significant difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the variation in solar cycles as the cutoff rigidity increases.