• 조명전기설비학회논문지
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• 제25권11호
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• pp.26-32
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• 2011

In this study, a standard illuminant A type LED that has similar emission spectrum as the standard illuminant A was developed using LED chip(emission peak: 405[nm]) and four types of phosphors(blue, green orangered and red). Using the design of experiment for spectrum control, the trend of the change of spectrum shape influenced by the change of interaction among phosphors and their density could be examined. Computer simulation through the optimization of the design of experiment revealed that, among four phosphors, the most influential one on the shape of the spectrum was green phosphor. Using the obtained optimal combination ratio of the four phosphors, an alternative LED illuminant to the actual standard illuminant A was developed and the spectrums of these two were confirmed identical. Using this standard illuminant A type LED, a portable transmittance meter with the range of measurement error of ${\pm}1.0$[%] was developed.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.605-608
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• 2009

이동 목표물 및 기상 현상 등의 원격탐지를 위한 레이다 시스템에서는 수신되는 전자파 반사 신호로부터 유용한 정보를 추출하기 위하여 각 거리별로 도플러 스펙트럼의 추정이 필요할 수 있다. 그러나 이제까지 일반적으로 적용되어졌던 FFT 주파수 추정방법은 안테나의 dwell time 이 짧은 경우 해상도 문제가 발생하거나 또는 상대적으로 강한 반사 신호의 부엽 확산으로 인하여 상대적으로 약한 목표물의 탐지가 어려울 수 있다. 따라서 본 논문에서는 이러한 문제점을 개선하기위하여 시간영역에서의 도플러 신호모델 파라메터 추정을 통한 효율적인 도플러 스펙트럼 추정방법에 관하여 비교하고 고찰하였다.

• 한국지진공학회논문집
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• 제25권1호
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• pp.33-42
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• 2021

The design response spectrum presented in the seismic design standard reflects the characteristics of the tectonic environment at a site. However, since the design response spectrum does not represent the ground motion with a specific earthquake magnitude or distance, input ground motions for response history analysis need to be selected reasonably. It is appropriate to use observed ground motions recorded in Korea for the seismic design. However, recently recorded ground motions in the Gyeongju (2016) or Pohang (2017) earthquakes are not compatible with the design response spectrum. Therefore, it is necessary to convert the recorded ground motion in Korea to a model similar to the design response spectrum. In this study, several approaches to adjust the spectral acceleration level at each period range were tested. These are the intrinsic and scattering attenuation considering the earthquake environment, magnitude, distance change by the green function method, and a rupture propagation direction's directivity effect. Using these variables, the amplification ratio for the representative natural period was regressed. Finally, the optimum condition compatible with the design response spectrum was suggested, and the validation was performed by converting the recorded ground motion.

• Earthquakes and Structures
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• 제8권5호
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• pp.1241-1254
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• 2015

Spatially variable ground motions can be significant on the seismic response of a structure due to the incoherency of the incident wave. Incoherence of the incident wave is resulted from wave passage and wave scattering. In this study, wave passage effect on the response spectrum of a building structure built on a soft soil layer was investigated utilizing a finite element program of P3DASS (Pseudo 3-dimensional Dynamic Analysis of a Structure-soil System). P3DASS was developed for the axisymmetric problem in the cylindrical coordinate, but it is modified to apply anti-symmetric input earthquake motions. Study results were compared with the experimental results to verify the reliability of P3DASS program for the shear wave velocity of 250 m/s and the apparent shear wave velocities of 2000-3500 m/s. Studied transfer functions of input motions between surface mat foundation and free ground surface were well-agreed to the experimental ones with a small difference in all frequency ranges, showing some reductions of the transfer function in the high frequency range. Also wave passage effect on the elastic response spectrum reduced the elastic seismic response of a SDOF system somewhat in the short period range.

• 말소리와 음성과학
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• 제8권2호
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• pp.65-71
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• 2016

The purpose of this study is to examine the prosodic pattern of the children with high functioning autism spectrum disorder(HFASD) according to sentence type. The participants were 18 children aged from 7 - 9 years; 9 children with HFASD and 9 typical development children(TD) of the same chronological age with HFASD children. Sentence reading tasks were conducted in this study. Seven interrogative sentences and 7 declarative sentences were presented to the participants and were asked to read the sentences three times. Mean values of F0, F0 range, intensity, speech rate and pitch contour were measured for each sentence. The results showed that for F0 range, significant main effect and interaction effect were observed in the subject group and sentence type. There were significant differences in intensity, mean F0, speech rate, pitch contour across sentence types. The results of this study indicated that HFASD showed no difference in intonation across sentence types. Speakers' intention may have a negative effect on pragmatic aspects. These results suggest that the assessment and intervention of prosody be important for HFASD.

• 대한방사선기술학회지:방사선기술과학
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• 제39권4호
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• pp.637-642
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• 2016

본 연구에서는 TMPTA와 DHPA를 모체로 Ultima $Gold^{TM}$ LLT 유기 섬광체를 혼합하여 자외선에 광중합 특성을 가진 플라스틱 섬광체를 처음으로 제작하고, 그 섬광특성을 조사하였다. 제조된 플라스틱 섬광체의 발광스펙트럼 파장 범위는 380~520 nm이었으며, 중심파장은 423 nm 었다. 400~800 nm의 파장범위에 대하여 50% 이상의 투명도를 나타내었으며, 섬광체의 섬광 감쇠 시간특성이 12 ns인 1개의 성분이 측정되었다. 제작된 플라스틱 섬광체의 발광파장 스펙트럼이 광전자증배관의 양자효율 특성과 잘 매칭되며, 향후 3D 프린팅 소재로서의 최적화 공정 개발을 통해 3D 프린팅 기술에 접목함으로써 인체 도시메트리에 활용하고자 한다.

• 한국통신학회논문지
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• 제25권1B호
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• pp.175-182
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• 2000

적외선을 이용한 수/발광 다이오드에 집적소자를 혼합한 Hybrid형 단거리 광무선 통신용 원칩모듈을 개발하였다. 발광다이오드는 850nm 의 적외선파장을 30$^{\circ}$지향각을 갖는 AlGaAs계 고속신호용으로서 전파지연이 60 ns 이며, PIN 포토다이오드는 Si계 반도체 수광소자로써 450-1050nm의 파장대에서 수광 흡수율이 양호하고 필터겸용 블록 에포시렌즈를 750nm 파장 저역대를 여과시켰다. 데이터 전송속도는 115.2 kbps이며 IrDA1.0 SIR 표준조건에서 동작이 양호함을 확인하였다.

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.54-61
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• 1988

This paper was a study on dielectric phenomena of the specimen, Polypropylene films which were annealled in air and quenched in liquid nitrogen after aging for 5[hr] in water of 100[.deg.C]. The specimen was measured in temperature range of 15-120[.deg.C] and in frequency range of 30-1x 10$^{6}$ [HZ]. As the results of the study, it was confirmed that the tacticity of specimen was isotactic structure, and the degree of cryatallinity of the specimens calculated by means of Natta's method from XRD (X-ray Diffraction) spectrum was 55[%]. And for dielectric relaxation, .betha. peak-the tan .delta. (spectrum around 20[.deg.C])-attributed due to amorphous regions, and .alpha. peak - the tan .delta. spectrum around 90[.deg.C]-due to crystalline regions. It was identified that the degree of crystallinity of the specimen quenched in the liquid nitrogen was increased to 55-65[%], and that of the specimen annealled in the air was decreased to 55-50[%]. And activation energy from dielectric loss spectra was obtained 34.5[kcal/mole] for .alpha. peak and 80.5[kcal/mole] for .betha. peak, respectively.

• 인터넷정보학회논문지
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• 제12권1호
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• pp.1-10
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• 2011

스펙트럼 검출은 인지 무선 시스템(Cognitive Radios) 구현을 위한 핵심 기술들 중의 하나이다. 스펙트럼 검출에서 문제시되는 점들 중에 하나는 페이딩(Fading) 및 쉐도윙(Shadowing) 등으로 인해서 스펙트럼 검출 성능이 저하된다는 것이다. 이 문제점을 해결하기 위해 제안된 방법 중 하나가 협력 스펙트럼 검출 방법이다. 이 방법을 통해 비협력 스펙트럼 검출 방식의 성능을 개선할 수 있지만, 여전히 큰 장애물과 같은 간섭 요인에 의해 스펙트럼 성능이 영향을 받는다는 단점이 있다. 특히, 기존의 대부분의 연구에서는 고정된 1차 사용자(Primary User, PU)를 고려하고 있지만 향후 유비쿼터스(Ubiquitous) 환경에서는 이동성을 가지는 1차 사용자가 존재하는 시스템을 고려해야 한다. 이러한 환경에서 기존의 협력 스펙트럼 검출 방식은 정확성이 낮은 검출 성능을 보이고 고려하지 않아도 될 2차 사용자(Cognitive User, CR user)의 국부 센싱값을 전송함으로써 많은 에너지를 소비하는 문제점이 있다. 본 논문에서는 이러한 문제를 해결하기 위해서, 무선 인지 시스템에서의 이동성을 가지는 1차 사용자의 위치를 추정하고 이를 기반으로 간섭 영향을 받는 2차 사용자를 검출한다. 또한 검출된 간섭영향을 받는 2차 사용자의 센싱 정보를 융합 결정할 때 배제함으로써 스펙트럼 검출의 정확성을 높이는 방법을 제안하다. 시뮬레이션을 통하여 제안된 알고리즘이 기존 알고리즘 보다 정확한 스펙트럼 검출을 보인다.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4335-4354
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• 2024

Some core designs integrate high-enriched fuel and moderator materials to enhance neutron utilization. This combination results in a broad spectrum within the system, posing challenges in resonance calculation. This paper introduces a general framework to realize resonance self-shielding treatment in broad-spectrum fuel lattice problems. The framework consists of three components. First, a new energy group structure is devised to support resonance calculation in the entire energy range and capture spectral transition and thermalization effects during eigenvalue calculation. Second, the subgroup method based on narrow approximation is selected as a universal method to perform resonance calculation. Finally, transport equations for each fissionable region are solved for neutron flux to collapse the fission spectrum. The proposed method is verified against fast, intermediate, and thermal spectrum pin cell problems and an assembly problem featuring a fast-thermal coupled spectrum. Numerical results affirm the accuracy of the proposed method in handling these scenarios, with eigenvalue errors below 154 pcm for pin cell problems and 106 pcm for the assembly problem. The verification results revealed that the proposed method enables accurate resonance self-shielding treatment for broad-spectrum problems.