• 정보저장시스템학회논문집
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• 제9권1호
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• pp.10-16
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• 2013

Through the rapid development of LED TV, a large-area edge-lit backlight unit is widely researched in the display industry for enhancing the optical efficiency, luminous uniformity and slim design. In addition, an edge-lit backlight unit includes many optical sheets such as reflection sheet, prism sheet and diffuser sheet. However the function can be replaced by the carefully patterned light guide plate (LGP). Micro patterns which located on the top and bottom surface of light guide plate was designed by ray-tracing optical simulation. The designed patterns improved the light characteristics of LGP, including optical extraction efficiency and intensity distribution uniformity. These results suggest that it is very effective method to design edge-lit LGP with micro-patterns on both sides for large-area display and to reduce the fabrication cost.

• 품질경영학회지
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• 제26권3호
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• pp.71-81
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• 1998

In reliability analysis, the time difference between the expected next failure time and the current failure time or the Mean Time Between Failure(MTBF) is of significant interest. Until recently, in reliability growth studies, the reciprocal of the intensity function at current failure time has been used as being equal to MTBE($t_n$)at the n-th failure time $t_n$. That is MTBF($t_n$)=l/$\lambda (t_n)$. However, such a relationship is only true for Homogeneous Poisson Process(HPP). Tsokos(1995) obtained the upper bound and lower bound for the MTBF($t_n$) and proposed an estimator for the MTBF($t_n$) as the mean of the two bounds. In this paper, we provide the estimator for the MTBF($t_n$) which does not depend on the value of the shape parameter. The result of the Monte Carlo simulation shows that the proposed estimator has better efficiency than Tsokos's estimator.

• 대한토목학회논문집
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• 제14권5호
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• pp.1129-1136
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• 1994

지점 강우 과정을 물리적으로 모형화하였다. 모형의 입력 변수는 지상의 기상 변수이다. 모형의 성분은 관측치와 구름 물리학의 선행 연구를 토대로 매개 변수화되었다. 특별히 강조되는 것은 집적 효율을 평가하는 것이다. 수정 비대칭 모형의 수운적 크기 분포 함수를 적용한 결과 그 모형은 호우에 적합하였다. 모형에 포함된 주요 매개변수는 최적화 기법에 의하여 평가하였다. 강우 강도는 평가된 매개변수의 중앙값을 사용하여 예측하였다.

• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.19-22
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• 1997

The photorefractive properties of 4% mol magnesium oxide doped lithium niobate have been investigated at room temperature. The recording and erasing time constants were measured as a function of intensity and analyzed by using the two active species (electron-hole) model. The results were used to compute the exposure schedule for multiple hologram recording. We have recorded grating of five holograms by angular multiplexing at room temperature and fixed them by means of a thermal cycling procedure. The highest diffraction efficiency of a fixed grating is up to 50% of an unfixed one.

• Nuclear Engineering and Technology
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• 제21권3호
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• pp.216-222
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• 1989

원자력병원에 설치되어 있는 MC-50 싸이클로트론은 중성자 치료와 의학용 동위원소 생산을 위해 가동중에 있다. 본 논문에서는 MC-50의 설계 특징, 기계적 구조, 가동 특성에 대하여 기술하고 있다. 본 싸이클로트론의 최적 가동 조건은 반복적인 운전에 의해 결정되었으며, 내부 빔의 성능은 싸이클로트론 반경의 함수로서 내부 빔의 세기 및 공간 분포 측정을 통해 조사되어졌다. 일상적으로, 인출효율이 61%일 때 40$\mu$A세기의 50 MeV 양성자 빔을 얻었다.

• 융합보안논문지
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• 제12권1호
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• pp.9-16
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• 2012

소프트웨어 시스템의 대규모자료의 적용 때문에 소프트웨어 신뢰도는 소프트웨어 개발에 중요한 역할을 해왔다. 본 연구에서는 고장시간에 관련된 소프트웨어 신뢰성장모형이 제안되었다. 이러한 검사시간은 미리 정해진 절단 고정 시간을 의미한다. 본 연구에서는 소프트웨어의 강도함수, 평균값 함수 및 신뢰도와 모수추정에 대하여 나열하고 파레토 분포를 수명분포로 적용한 비동질적인 포아송 과정을 적용하였다. 본 논문의 수치적인 예에서는 고장 간격 시간 자료를 적용하고 모수추정 방법은 최우 추정 법을 이용하고 추세분석을 통하여 자료의 효율성을 입증한 후 평균자승오차와 $R_{SQ}$(결정계수)를 이용하고 예측 값과 실제 값의 차이에 의존한 효율적인 모형을 선택 비교하였다.

• 한국방사선학회논문지
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• 제11권5호
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• pp.353-359
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• 2017

대표적인 저강도 초음파 자극 기술인 음파영동은 초음파의 물리적 진동과 온열 효과를 이용하여 약물을 인체 표피 내부로 전달시키는 기법이다. 음파영동법은 치료 약물 전달의 효율을 높일 수 있으며, 인슐린이나 지질 등 분자 크기가 비교적 큰 약물의 전달에도 효과적이라는 장점을 갖는다. 본 연구에서는 효율적인 음파영동 치료를 위하여 대면적 단일 진동소자와 치료 부위에 약물 이송 기능을 갖는 복합 구조 초음파 변환기 어셈블리를 제안하였다. 또한, 치료 부위의 온도를 상승 및 유지시킬 수 있는 변환기 어셈블리 구조를 제안하고 유효성을 평가하였다. 본 연구에서 제안된 변환기 어셈블리는 지속적으로 정량의 약물을 제공하고, 가온을 통하여 약물 전달을 보조함으로써 초음파를 이용한 음파영동 시술의 효율을 향상시킬 수 있을 것으로 사료된다.

• 한국재료학회지
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• 제22권3호
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• pp.140-144
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• 2012

Compared with bulk material, quantum dots have received increasing attention due to their fascinating physical properties, including optical and electronic properties, which are due to the quantum confinement effect. Especially, Luminescent CdSe quantum dots have been highly investigated due to their tunable size-dependent photoluminescence across the visible spectrum. They are of great interest for technical applications such as light-emitting devices, lasers, and fluorescent labels. In particular, quantum dot-based light-emitting diodes emit high luminance. Quantum dots have very high luminescence properties because of their absorption coefficient and quantum efficiency, which are higher than those of typical dyes. CdSe quantum dots were synthesized as a function of the synthesis time and synthesis temperature. The photoluminescence properties were found strongly to depend on the reaction time and the temperature due to the core size changing. It was also observed that the photoluminescence intensity is decreased with the synthesis time due to the temperature dependence of the band gap. The wavelength of the synthesized quantum dots was about 550-700 nm and the intensity of the photoluminescence increased about 22~70%. After the CdSe quantum dots were synthesized, the particles were found to have grown until reaching a saturated concentration as time increased. Red shift occurred because of the particle growth. The microstructure and phase developments were measured by transmission electron microscopy (TEM) and X-ray diffractometry (XRD), respectively.

• Computers and Concrete
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• 제12권2호
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• pp.211-228
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• 2013

The structure analyzed in this paper has particular building style and special structural system. It is a rigid-connected twin-tower skyscraper with asymmetrical distribution of stiffness and masses in two towers. Because of the different stiffness between the north and the south towers, the torsion seismic vibration is significant. In this paper, in order to study the seismic response of the structure under both frequent low-intensity earthquakes as well as rare earthquakes at the levels of intensity 7, the analysis model is built and analyzed with NosaCAD. NosaCAD is an nonlinear structure analysis software based on second-development of AutoCAD with ObjectARX. It has convenient modeling function, high computational efficiency and diversity post-processing functions. The deformations, forces and damages of the structure are investigated based on the analysis. According to the analysis, there is no damage on the structure under frequent earthquakes, and the structure has sufficient capacity and ductility to resist rare earthquakes. Therefore the structure can reach the goal of no damage under frequent earthquakes and no collapse under rare earthquakes. The deformation of the structure is below the limit in Chinese code. The time sequence and distribution of damages on tubes are reasonable, which can dissipate some dynamic energy. At last, according to forces, load-carrying capacity and damage of elements, there are some suggestions on increasing the reinforcement in the core tube at base and in stiffened stories.

• 대한후두음성언어의학회지
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• 제15권1호
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• pp.21-26
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• 2004

Vocal Register Transition(Passaggio) is one of the most important vocal technique for classically trined male singers(tenor). Passaggio is that it bridges the chest register to head register without a noticeable voice break. Vocalist gest the feeling that voice is not locked a particular register. The purpose of this study was to clarify the difference between easy($B_3$) tone and non passaggio(F#_4$) & passaggio(F#_4$). We selected 6 trained singers(tenor), who had more than 12.6 years of experience and were well trained in passaggio technique. Simulataneous measurement was performed frequency(F0), mean flow rate(MFR), intensity(I), and subglottal pressure(Psub) using a phonatory function analyzer(Nagashima) and Closed Quotient(CQ), Jitter, Shimmer, NHR a Electro-glottography(EGG) of Lx. Speech Studio(Laryngogrph Lt, London, UK) and vocal efficiency was calculated by Carroll's method. For the tenor, target tone/a/was measured in three conditions : 1) easy phonation : $B_3$, 2) high tone without passaggio : F#_4$, 3) high tone with passaggio : F#_4$). The results revealed that F0 of the target tones between non-passaggio group and passaggio group were not significantly different though higher is F0, higher is subglottal pressure. And also CQ, MFR, Psub were increased in passagio than nonpssagio but these values were not statistically different. This study concluded that passaggio is the vocal technique to make the same quality of tone between chest register and head register in tenor.