• ETRI Journal
• /
• 제31권6호
• /
• pp.667-674
• /
• 2009

Terahertz time-domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: $Ge_{30}As_8Ga_2Se_{60}$, $Ge_{35}Ga_5Se_{60}$, and $Ge_{10}As_{20}S_{70}$. The absorption coefficients ${\alpha}({\nu})$, complex refractive index n(${\nu}$), and complex dielectric constants ${\varepsilon}({\nu})$ were measured in a frequency range from 0.3 THz to 1.5 THz. The measured real refractive indices were fitted using a Sellmeier equation. The results show that the Sellmeier equation fits well with the data throughout the frequency range and imply that the phonon modes of glasses vary with the glass compositions. The theory of far-infrared absorption in amorphous materials is used to analyze the results and to understand the differences in THz absorption among the sample glasses.

• Journal of applied mathematics & informatics
• /
• 제10권1_2호
• /
• pp.41-50
• /
• 2002

We provide local and semilocal theorems for the convergence of Newton-like methods to a locally unique solution of an equation in a Banach space. The analytic property of the operator involved replaces the usual domain condition for Newton-like methods. In the case of the local results we show that the radius of convergence can be enlarged. A numerical example is given to justify our claim . This observation is important and finds applications in steplength selection in predictor-corrector continuation procedures.

• 한국융합학회논문지
• /
• 제13권2호
• /
• pp.13-20
• /
• 2022

본 연구는 딥러닝 기법을 활용하여 범죄 수사 도메인에 특화된 개체명 인식 모델을 개발하는 연구이다. 본 연구를 통해 비정형의 형사 판결문·수사 문서와 같은 텍스트 기반의 데이터에서 자동으로 범죄 수법과 범죄 관련 정보를 추출하고 유형화하여, 향후 데이터 분석기법을 활용한 범죄 예방 분석과 수사에 기여할 수 있는 시스템을 제안한다. 본 연구에서는 범죄 수사 도메인 텍스트를 수집하고 범죄 분석의 관점에서 필요한 개체명 분류를 새로 정의하였다. 또한 최근 자연어 처리에서 높은 성능을 보이고 있는 사전학습 언어모델인 KoELECTRA를 적용한 제안 모델은 본 연구에서 정의한 범죄 도메인 개체명 실험 데이터의 9종의 메인 카테고리 분류에서 micro average(이하 micro avg) F1-score 99%, macro average(이하 macro avg) F1-score 96%의 성능을 보이고, 56종의 서브 카테고리 분류에서 micro avg F1-score 98%, macro avg F1-score 62%의 성능을 보인다. 제안한 모델을 통해 향후 개선 가능성과 활용 가능성의 관점에서 분석한다.

• 한국정보통신학회논문지
• /
• 제25권11호
• /
• pp.1477-1485
• /
• 2021

최근 이미지 초해상도는 정수배율만 가능한 모델에만 집중적으로 연구되고 있다. 하지만 관심 객체 인식, 디스플레이 화질 개선 등 실제 초해상도 기술의 대표 적용 분야에서는 소수 배율을 포함하는 임의배율 확대 필요성이 대두되고 있다. 본 논문에서는 기존 정수배율 모델의 가중치를 활용하여 임의배율을 실행할 수 있는 모델을 제안한다. 이 모델은 정수배율에 의해 우수한 성능을 가진 초해상도 결과를 DCT 스펙트럼 도메인으로 변환하여 임의배율을 위한 공간을 확장한다. DCT 스펙트럼 도메인에 의한 확장으로 인해 발생하는 이미지의 고주파 정보 손실 문제를 줄이기 위해 고주파 스펙트럼 정보를 적절히 복원할 수 있는 모델인 고주파 집중 네트워크를 제안한다. 제안된 네트워크는 고주파 정보를 제대로 생성하기 위해서 RGB 채널간의 상관관계를 학습하는 레이어인 channel attention을 활용하고, 잔차 학습 구조를 통해 모델을 깊게 만들어 성능을 향상시켰다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권3호
• /
• pp.266-281
• /
• 2017

Hydroelastic interactions of a deformable floating body with random waves are investigated in time domain. Both hydroelastic motion and structural dynamics are solved by expansion of elastic modes and Fourier transform for the random waves. A direct and efficient structural analysis in time domain is developed. In particular, an efficient way of obtaining distributive loads for the hydrodynamic integral terms including convolution integral by using Fubini theory is explained. After confirming correctness of respective loading components, calculations of full distributions of loads in random waves are expedited by reformulating all the body loading terms into distributed forms. The method is validated by extensive convergence tests and comparisons against the counterparts of the frequency-domain analysis. Characteristics of motion/deformation responses and stress resultants are investigated through a parametric study with varying bending rigidity and types of random waves. Relative contributions of componential loads are identified. The consequence of elastic-mode resonance is underscored.

• 대한전자공학회논문지
• /
• 제22권2호
• /
• pp.18-24
• /
• 1985

주파수 영역-적응 필터는 시간 영역-원응 필터에 비하여 필터 차수가 일정치 이상으로 높아졌을 경우에는 계산량에 있어서 유리하게 된다. 본 논문에서는 각파수 영역-적응 필터 알고리즘에 관하여 μ-FLMS 알고리즘이라는 하나의 새로운 형태를 재시하였으며, 이 알고리즘과 시간 영역-적응 필터 μ-FLMS 알고리즘의 특성을 비교하였다. 두 필터의 특성을 비교한 결과, 동일한 수검속도하에서 주파수 영역-적응 필터가 계산량에서 유리하였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제37회 하계학술대회 초록집
• /
• pp.250-250
• /
• 2009

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2023년도 추계학술발표대회
• /
• pp.908-909
• /
• 2023

Recently, several generative models have emerged and are being used in various industries. Among them, Cycle GAN is still used in various fields such as style transfer, medical care and autonomous driving. In this paper, we propose two methods to improve the performance of these Cycle GAN model. The ReLU activation function previously used in the generator was changed to Leaky ReLU. And a new loss function is proposed that considers the semantic level rather than focusing only on the pixel level through the VGG feature extractor. The proposed model showed quality improvement on the test set in the art domain, and it can be expected to be applied to other domains in the future to improve performance.

• 융합경영연구
• /
• 제9권6호
• /
• pp.1-13
• /
• 2021

Purpose: This research explores how domain passion in addition to entrepreneurial passion influences innovation strategy of venture, thus expanding the role of passion in choosing the path for innovation strategy. Passion is considered one of the most debated concepts in entrepreneurship, psychology, and marketing literatures, and yet a framework describing the integrated effect of entrepreneurial and domain passion on innovation strategy of venture is still lacking. Research data and methodology: Based on an inductive qualitative approach, the research addresses these issues via analyzing four unique cases of independently owned restaurants in Pakistan. The research focusses on the entrepreneurs who startup a venture out of a passion for a specific domain and have a passion for entrepreneurship either from start or it fuels up later during entrepreneurial process. Results: In the presence of both types of passions (Domain and entrepreneurial), the individuals will be inclined towards ambidexterity which differ in types from case to case according to different combinations and intensities (harmonious and obsessive) of passion. Conclusion: Research shows how innovation strategy of domain passion driven ventures is influenced by both entrepreneurial and domain passion, so to understand the role of passion in such cases integrated effect of both passions needs to be explored.

• Journal of the Optical Society of Korea
• /
• 제19권1호
• /
• pp.55-62
• /
• 2015

In this study we demonstrate ultrahigh-resolution spectral domain optical coherence tomography (UHR SD-OCT) with a linear-wavenumber (k) spectrometer, to accelerate signal processing and to display two-dimensional (2-D) images in real time. First, we performed a numerical simulation to find the optimal parameters for the linear-k spectrometer to achieve ultrahigh axial resolution, such as the number of grooves in a grating, the material for a dispersive prism, and the rotational angle between the grating and the dispersive prism. We found that a grating with 1200 grooves and an F2 equilateral prism at a rotational angle of $26.07^{\circ}$, in combination with a lens of focal length 85.1 mm, are suitable for UHR SD-OCT with the imaging depth range (limited by spectrometer resolution) set at 2.0 mm. As guided by the simulation results, we constructed the linear-k spectrometer needed to implement a UHR SD-OCT. The actual imaging depth range was measured to be approximately 2.1 mm, and axial resolution of $3.8{\mu}m$ in air was achieved, corresponding to $2.8{\mu}m$ in tissue (n = 1.35). The sensitivity was -91 dB with -10 dB roll-off at 1.5 mm depth. We demonstrated a 128.2 fps acquisition rate for OCT images with 800 lines/frame, by taking advantage of NVIDIA's compute unified device architecture (CUDA) technology, which allowed for real-time signal processing compatible with the speed of the spectrometer's data acquisition.