• 대한전자공학회논문지SD
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• 제42권10호
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• pp.47-54
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• 2005

본 논문에서는 불완전명세(incompletely-specified)를 가진 상태전이그래프(state transition graph: STG)상에서 리던던트 고장(redundant faults)수를 줄여 테스트를 용이하게 하기 위한 새로운 동기 순차회로의 합성방법을 제안한다. 이 STG 합성법에는 1) 구별전이(distinguishable transition)을 이용하여 무정의상태(undefined states)와 불완전명세된 입력전이를 추가하고, 2) 가능한 한 강연결(strongly-connected)이 되도록 하는 방법을 사용한다. 제안된 방법을 이용하여 MCNC 벤치마크 회로에 대해 실험한 결과, 대부분의 회로에 대해 무해 고장의 수가 현격히 줄어들어 높은 고장검출을 얻었다.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1819-1826
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• 2009

To enhance the automatic performance of existing predicting and planning algorithms that require a predefined probability of the states' transition, this paper proposes a multiple sequence generation system. When interacting with unknown environments, a virtual agent needs to decide which action or action order can result in a good state and determine the transition probability based on the current state and the action taken. We describe a sequential behavior generation method motivated from the change in the agent's state in order to help the virtual agent learn how to adapt to unknown environments. In a sequence learning process, the sensed states are grouped by a set of proposed motivation filters in order to reduce the learning computation of the large state space. In order to accomplish a goal with a high payoff, the learning agent makes a decision based on the observation of states' transitions. The proposed multiple sequence behaviors generation system increases the complexity and heightens the automatic planning of the virtual agent for interacting with the dynamic unknown environment. This model was tested in a virtual library to elucidate the process of the system.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4751-4758
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• 2022

Two-phase flow may almost exist in every branch of the energy industry. For the corresponding engineering design, it is very essential and crucial to monitor flow patterns and their transitions accurately. With the high-speed development and success of deep learning based on convolutional neural network (CNN), the study of flow pattern identification recently almost focused on this methodology. Additionally, the photographing technique has attractive implementation features as well, since it is normally considerably less expensive than other techniques. The development of such a two-phase flow pattern online monitoring system is the objective of this work, which seldom studied before. The ongoing preliminary engineering design (including hardware and software) of the system are introduced. The flow pattern identification method based on CNNs and transfer learning was discussed in detail. Several potential CNN candidates such as ALexNet, VggNet16 and ResNets were introduced and compared with each other based on a flow pattern dataset. According to the results, ResNet50 is the most promising CNN network for the system owing to its high precision, fast classification and strong robustness. This work can be a reference for the online monitoring system design in the energy system.

• 한국광학회지
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• 제9권4호
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• pp.221-226
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• 1998

$Er_2O_3$를 첨가한 $PbO-Bi_2O_3-Ga_2O_3$ 삼성분계 중금속 산화물 유리로부터 발생하는 $1.5\mu\textrm{m}$와 2.7$\mu\textrm{m}$ 등의 형광에 대하여 복사 천이율, 형광 수명, 흡수 및 유도 방출 단면적 등을 조사하였다. 중금속 산화물 유리의 낮은 포논 에너지($~500cm^{-1}$)로 인하여 기존 산화물 유리로부터 관찰할 수 없었던 형광들의 양자 효율이 크게 높아졌으며 방출 단면적도 증가하였다. 한편, 798 nm 여기광의 상향 전이를 통한 녹색과 적색의 형광이 방출됨을 확인하였고, 각 에너지 준위의 형광 수명을 이용하여 다중포논 완화(multiphonon relaxation)를 정량적으로 규명하였다. $Er^{3+}:^4S_{3/2}{\rightarrow}^4I_{15/2}$ 천이에 의한 녹색 형광은 기지 유리(host glass)의 밴드 갭(band gap)흡수에 의한 비복사 천이의 영향을 받으므로 이 형광의 양자 효율을 높이기 위해서는 유리를 불활성 기체 분위기에서 용융하거나 자외선쪽 투과단이 짧은 유리 망목 형성제(glass-vetwork former)가 첨가된 기지 조성을 선택하는 것이 바람직하다.

• 접착 및 계면
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• 제24권4호
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• pp.136-142
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• 2023

본 연구에서는 실리카원으로 Tetraethyl orthosilicate (TEOS)를 사용하고 주형으로 트리블럭 공중합체(P123)를 사용하여 산성 조건에서 자기조립 방법과 수열합성 과정을 거쳐서 잘 배열된 육방체 구조의 메조세공 배열구조를 가지는 다공성 실리카 물질(Surfactant-extracted SBA-15)을 합성하였다. Surfactant-extracted SBA-15는 약 980 nm의 크기를 가지는 짧은 로드의 입자 모양을 보여주었다. 그리고 표면적과 세공 직경은 각각 730 m²g^-1와 70.8 Å이었다. 한편, 포스트-합성방법(post-synthesis method)을 이용하여 메조세공 내에 아미노실란(3-aminopropyltriethoxysilane, APTES)을 그래프팅(grafting) 하였다. 아미노실란으로 개질된 메조다공성 실리카(APTES-SBA-15)는 잘 배열된 세공구조(p6mm)를 가지고 짧은 로드의 입자모양을 잘 유지 하였다. APTES-SBA-15의 표면적과 세공 직경은 각각 350 m²g^-1와 60.7 Å으로 감소하였다. APTES가 개질된 메조 다공성 실리카에 희토류 금속이온(Eu³⁺, Tb³⁺) 용액을 처리하여 메조세공 내에 희토류 금속 착물이 도입된 메조다공성 실리카 물질을 합성하였다. (Eu/APTES-SBA-15, Tb/APTES- SBA-15) 이들 물질은 λ_ex=250 nm 광에 의해 특징적인 광발광 스펙트라를 나타내었다. (Tb/APTES-SBA-15를 위하여 ⁵D₄→⁷F₅ (543.5 nm), ⁵D₄→⁷F₄ (583.5 nm), ⁵D₄→⁷F₃ (620.2 nm) 전이; Eu/APTES-SBA-15를 위하여 ⁵D0→⁷F₀ (577.7 nm), ⁵D0→⁷F₁ (592.0 nm), ⁵D0→⁷F₂ (614.9 nm), ⁵D₀→⁷F₃ (650.3 nm) and ⁵D₀→⁷F₄ (698.5 nm) 전이)

• 한국진공학회지
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• 제18권2호
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• pp.102-107
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• 2009

본 연구에서는 ZnO 박막을 성장하기 위한 plasma-assisted molecular beam epitaxy (PAMBE)에 장착된 플라즈마건에 13.56 MHz의 rf 전력을 인가하였을 때 발생되는 산소 플라즈마의 발광 스펙트럼을 광발광 분광기(optical emission spectroscopy: OES)를 이용하여 조사하였다. 실험은 산소 가스 유량을 1 sccm에서 20 sccm, rf 전력을 25W에서 250 W 범위에서 플라즈마건의 오리피스의 직경을 각각 3 mm 와 5 mm로 달리하여 행해졌다. 산소 플라즈마를 발생시켰을 때 오리피스의 직경에 상관없이 전형적인 산소 플라즈마의 발광 스펙트럼이 관측되었다. 특히 776.8 nm와 843.9 nm에서 $3p^{5}P-3s^{5}S^{0}$, $3p^{3}P-3s^{3}S^{0}$ 천이에 기인하는 강한 산소 원자 발광선이 관측되었다. 산소 유량과 rf 파워가 증가함에 따라 776.8 nm와 843.9 nm의 발광 세기는 증가하였고, 776.8 nm의 스펙트럼 발광 세기의 증가율이 843.9 nm의 스펙트럼 발광 세기 증가율보다 컸다. 또한 오리피스 직경이 3 mm일 때가 5 mm일 때보다 산소 플라즈마가 더 안정적으로 발생하였다.

• 천문학회보
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• 제40권1호
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• pp.80.1-80.1
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• 2015

We present a study of outflows on 24 embedded young stellar objects selected from the source list of the Dust, Ice, and Gas in Time (DIGIT) Herschel key program. To study the relation between the CO outflows observed in low-J transitions and the properties of protostars more consistently with a homogeneous data set, we mapped the CO outflows of the selected targets in the J = 1-0 and J = 2-1 lines with two Korean telescopes (SRAO and TRAO). We compare CO outflow force ($F_{CO}$) with the bolometric luminosity, ($L_{bol}$) bolometric temperature, and the FIR molecular line luminosities of CO, $H_2O$, OH, and [O I] detected by the Herschel-PACS observations. We find that $F_{CO}$ of J = 1-0 is greater than that of 2-1 by a factor of ~ 2. The well known correlation between $F_{CO\;2-1}$ and $L_{bol}$ is not very evident in our sample as a whole, but they show a rather strong correlation when IRAM 04191+1522 is excluded. IRAM 04191+1522 has relatively high $F_{CO\;2-1}$ in spite of its low $L_{bol}$. This object is a well-known VeLLO, which is believed in the quiescent phase of the episodic mass accretion in the embedded stage. $L_{bol}$ traces a current accretion, but $F_{CO\;2-1}$ traces accretion happened long ago. Therefore, the low-$L_{bol}$ with the high-$F_{CO\;2-1}$ can be explained by the episodic accretion. $F_{CO\;2-1}$ shows little correlation with individual FIR line luminosities of CO, $H_2O$, OH, while [O I] and total FIR line luminosity seem to have correlations with $F_{CO\;2-1}$. This result is interpreted as the accretion energy deposits on species differently depending on shock properties, but the total FIR line luminosity sums the total accretion energy dispersed to different species.

• 천문학회보
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• 제38권2호
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• pp.65.2-65.2
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• 2013

We present a study of outflows on 24 embedded young stellar objects (YSOs), which are selected from the sources of the Dust, Ice, and Gas in Time (DIGIT) Herschel key program. Molecular outflow activity, which is believed to have strong dependence on accretion process, is the most powerful in the early embedded phase of star formation and declines as the central protostars evolve to the main sequence stage. In order to study the relation between the CO outflow observed in low J transitions and the properties of protostars, we mapped the CO outows of the selected targets in J = 1-0 and J = 2-1 lines with the 14-m TRAO telescope and the 6-m SRAO telescope, respectively. We estimate CO outflow momentum fluxes (Fco) and compare with bolometric luminosity, Lbol, bolometric temperature, Tbol, and the FIR molecular line luminosities of CO, $H_2O$, OH and [O I], which were detected by the Herschel-PACS observations. We found that $Fco_{1-0}$ is greater than $Fco_{2-1}$, and the mean ratio is about 2. L1455-IRS3 and IRAM04191 have high Fco in spite of low $L_{bol}$. The well known correlation between Fco and $L_{bol}$. is not very evident from all our samples. However, Fco and $L_{bol}$. show a rather strong correlation if L1455-IRS3 and IRAM04191 are excluded. Fco shows little correlation with FIR line luminosities of individual species, while the total FIR line luminosity summed over CO, $H_2O$, OH, and [OI] lines seems to have some correlation. In addition, we report 22 GHz $H_2O$, and 44 GHz CH3OH maser line detections in four sources out of the 24 YSOs.

• Current Photovoltaic Research
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• 제8권1호
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• pp.33-38
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• 2020

Single-phased SnS thin films have been prepared by RF magnetron sputtering at various deposition pressures. The effect of deposition pressure on the structural and optical properties of polycrystalline SnS thin films was studied using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer. The XRD analysis revealed the orthorhombic structure of the SnS thin films oriented along the (111) plane direction. As the deposition pressure was increased from 5 mTorr to 15 mTorr, the intensity of the peak on the (111) plane increased, and the intensity decreased under the condition of 20 mTorr. The binding energy difference at the Sn 3d_5/2 and S 2p_3/2 core levels was about 324.5 eV, indicating that the SnS thin film was prepared as a pure Sn-S phase. The optical properties of the SnS thin films indicate the presence of direct allowed transitions with corresponding energy band gap in the rang 1.47-1.57 eV.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2358-2368
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• 2011

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, employing the B3LYP method and the LANL2DZ, 6-31G$^*$(LANL2DZ for Tc), 6-31G$^*$(cc-pVDZ-pp for Tc) and DGDZVP basis sets, have been performed to investigate the electronic structures and absorption spectra of the technetium-99m-labeled methylenediphosphonate ($^{99m}Tc$-MDP) complex of the simplest diphosphonate ligand. The bonding situations and natural bond orbital compositions were studied by the Mulliken population analysis (MPA) and natural bond orbital (NBO) analysis. The results indicate that the ${\sigma}$ and ${\pi}$ contributions to the Tc-O bonds are strongly polarized towards the oxygen atoms and the ionic contribution to the Tc-O bonding is larger than the covalent contribution. The electronic transitions investigated by TDDFT calculations and molecular orbital analyses show that the origin of all absorption bands is ascribed to the ligand-to-metal charge transfer (LMCT) character. The solvent effect on the electronic structures and absorption spectra has also been studied by performing DFT and TDDFT calculations at the B3LYP/6-31G$^*$(cc-pVDZ-pp for Tc) level with the integral equation formalism polarized continuum model (IEFPCM) in different media. It is found that the absorption spectra display blue shift in different extents with the increase of solvent polarity.