• 대한전자공학회논문지SD
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• 제40권9호
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• pp.666-672
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• 2003

본 논문에서는 광의 결합 메커니즘이 다른 ITG(integrated-twin-guide) 와 BT(butt coupled) 구조를 가지는 두 종류의 파장 가변 DBR-LD의 제작공정과 성능에 대해서 기술하였다. 두 종류의 DBR-LD는 PBH(planar buried heterostructure) 구조론 가지며, MOVPE 성장으로 제작하였다. 제작된 DBR-LD 광출력 특성을 측정한 결과 BT-DBR-LD가 ITG-DBR-LD보다 임계전류 변화폭, 광출력 변화 폭, 기울기 효율에서 2배 이상의 우수한 특성을 나타내었다. 그리고, 준 연속 파장 가변 특성은 BT-DBR-LD가 7.2nm, ITG-DBR-LD가 7.4nm 이며, SMSR이 35dB 이상으로 우수하게 나타났다. 이와 같이 BT DBR-LD가 특성이 우수한 것은 BT 구조가 ITG 구조보다 높은 결합 효율을 나타내기 때문이다.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.195-200
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• 2003

A two-dimensional "twin-jet counterflow" burner has been designed for the better understanding of the stability of turbulent flames. This flow system enables one to systematically investigate various effects on non-premixed flames, including the effects of curvature, negative strain, and non-premixed flame interactions. The objective of this study is comparing characteristics of extinction of non-premixed methane flames with that of non-premixed propane flames investigated previously. The extinction limit of non-premixed methane and propane flames can be extended compare to that for the conventional counterflow non-premixed flame because of the existence of petal shaped flame and have same structure. The hysteresis in transition between the petal shaped flame and the curved two-wing flames could be observed. We could find differences between non-premixed methane flame and non-premixe propane flame such as the position of one wing extinction and the regime of one wing extinction.

• 한국멀티미디어학회논문지
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• 제24권12호
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• pp.1682-1692
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• 2021

Digital Twin, one of the core technologies of the Fourth Industrial Revolution, is attracting attention as a very suitable technology for disaster monitoring such as fires and earthquakes. In this paper, we implement a system equipped with UWB RTLS(Ultra-Wideband Real Time Location System), real-time remote control, and video streaming, which are element technologies for disaster monitoring digital twin. Since the proposed system structure is based on a cloud server, the actual location of the UWB indoor positioning-based client is transmitted to the user device in real time and stored on the cloud server for statistical and data analysis. In addition, we demonstrate through experiments that outliers occurs when the value of RSSI(Received Signal Strength Indicator) decreases due to communication collisions between UWB Tags, and propose an RSSI outlier correction algorithm to solve this problem.

• 전자공학회논문지D
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• 제35D권9호
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• pp.54-61
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• 1998

Deep submicron급 CMOS디바이스에서 래치업 면역특성을 향상시키기 위한 새로운 Triple well구조를 제안하였다. Triple well에서 이온주입 에너지와 도즈량 변화에 따른 최적인 래치업 면역을 위한 공정조건을 확립하고 이것을 기존의 Twin well구조와 비교분석하였다. 공정은 공정시뮬레이터인 ATHENA로 소자를 제작하여 도핑프로파일과 구조를 해석하고 래치업 특성은 소자시뮬레이터인 ATLAS를 사용하였다. Triple well과 Twin well의 구조에서 공정상의 차이가 도핑프로파일에 미치는 영향과 프로파일 형태가 래치업 특성에 미치는 영향을 규명하였다. Triple well구조에서 p-well이온주입에너지 2.5MeV, 도즈량 1×10/sup 14/[cm/sup -2/]일 때 트리거 전류가 2.5[mA/${\mu}{m}$]로 매우 큰 래치업 면역특성을 얻었다.

• 한국BIM학회 논문집
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• 제9권1호
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• pp.42-51
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• 2019

Maintenance of aging structures has attracted societal attention. Maintenance of the aging structure can be efficiently performed with a digital twin. In order to maintain the structure based on the digital twin, it is required to accurately detect the damage of the structure. Meanwhile, deep learning-based damage detection approaches have shown good performance for detecting damage of structures. However, in order to develop such deep learning-based damage detection approaches, it is necessary to use a large number of data before and after damage, but there is a problem that the amount of data before and after the damage is unbalanced in reality. In order to solve this problem, this study proposed a method based on Generative adversarial network, one of Generative Model, for generating acceleration data usually used for damage detection approaches. As results, it is confirmed that the acceleration data generated by the GAN has a very similar pattern to the acceleration generated by the simulation with structural analysis software. These results show that not only the pattern of the macroscopic data but also the frequency domain of the acceleration data can be reproduced. Therefore, these findings show that the GAN model can analyze complex acceleration data on its own, and it is thought that this data can help training of the deep learning-based damage detection approaches.

• 한국분무공학회지
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• 제6권1호
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• pp.9-17
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• 2001

The effect of air entrainment in twin-fluid spray structure is investigated experimentally by varing the amount of itemizing air. The air entrainment is expected to affect on droplet size and velocity, droplet number density, turbulent kinetic energy and vorticity. PDA(Phase Doppler Anemometer) and PIV(Particle Image Velocimetry) system are used to measure those important factors in analyzing spray structure. The results show that spray structure consists of three distinctive regions ; the atomizing region near nozzle, characterizing strong convective effect, the central core region where droplets are accelerated, and the spray sheath region where droplets are decelerated due to air entrainment. The local air entrainment rate is largest near nozzle, characterizing strong turbulent kinetic energy and vorticity but deceases along axial distance.

• Restorative Dentistry and Endodontics
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• 제4권1호
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• pp.7-9
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• 1978

Brass specimen, copper based alloy was prepared in cubic form about $1cm{\times}1cm{\times}1cm$ in volume. The specimens were mechanically compressed in one direction until the dimension distorted to 20%, 40%, 60% and 80% in length. The compressed specimens with 80% distorted in length were then heat treated in $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$ for 30 minutes. Microscopic examination was made on both compressed and heat treated specimens. The results obtained from the study were as follows: 1. Grain boundary and twin phenomenon was clearly seen in 0% and 20% compressed cases. Slip bands was appeared in 40% cases and distributed equally as well as twin. 2. The first evidence of slip bands was observed in 20% and the bands grew thicker and denser as the compression increased. 3. The density of the bands were reduced after annealing in $200^{\circ}C$ and completely disappeared at $300^{\circ}C$ cases. 4. Recrystallization was noticed unevenly in $300^{\circ}C$ cases and the evidence of twin was observed in these crystallized area. 5. In $400^{\circ}C$ cases the grain boundary was evenly found and the twin phenomenon was clearly observed. Grain boundary and twin was noticeably formed in size according to the annealing temperature increased.

• 한국인터넷방송통신학회논문지
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• 제23권5호
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• pp.89-95
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• 2023

지하공동구는 도시의 상하수, 전력, 통신 등과 같은 중요한 시설을 수용하여 관리하는 도시기반시설로 화재, 지진, 침수 등과 같은 재난으로부터 보호해야 하는 국가 시설이다. 예측, 예방, 대비, 대응, 복구 등의 재난안전 전주기 관리 체계를 구축함에 있어서 첨단 ICT 기술과 데이터가 융합된 디지털 트윈 기술을 활용하여 지하공동구의 재난안전관리 플랫폼을 개발 중에 있다. 이 논문에서는 재난안전 디지털 트윈에 대한 성숙도 모델을 살펴보고 각 성숙도 단계 별 재난안전 디지털 트윈 구현을 위해 필요한 데이터셋을 정의하였다. 정의된 데이터셋의 카테고리의 조합에 따라 성숙도 단계를 다르게 하여 디지털 트윈 구현이 가능하도록 구성하였다.

• 도시과학
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• 제7권2호
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• pp.53-60
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• 2018

Digital Twin is a technology that creates a photocopy of real-world objects on a computer and analyzes the past and present operational status by fusing the structure, context, and operation of various physical systems with property information, and predicts the future society's countermeasures. In particular, 3D rendering technology (UAS, LiDAR, GNSS, etc.) is a core technology in digital twin. so, the research and application are actively performed in the industry in recent years. However, UAS (Unmanned Aerial System) and LiDAR (Light Detection And Ranging) have to be solved by compensating blind spot which is not reconstructed according to the object shape. In addition, the terrestrial LiDAR can acquire the point cloud of the object more precisely and quickly at a short distance, but a blind spot is generated at the upper part of the object, thereby imposing restrictions on the forward digital twin modeling. The UAS is capable of modeling a specific range of objects with high accuracy by using high resolution images at low altitudes, and has the advantage of generating a high density point group based on SfM (Structure-from-Motion) image analysis technology. However, It is relatively far from the target LiDAR than the terrestrial LiDAR, and it takes time to analyze the image. In particular, it is necessary to reduce the accuracy of the side part and compensate the blind spot. By re-optimizing it after fusion with UAS and Terrestrial LiDAR, the residual error of each modeling method was compensated and the mutual correction result was obtained. The accuracy of fusion-based 3D model is less than 1cm and it is expected to be useful for digital twin construction.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.655-658
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• 2007

Characteristics of Al cathode films deposited by using specially designed twin target sputter (TTS) system were investigated. It was found that Al cathode films prepared by TTS were amorphous structure with nanocrystallines due to low substrate temperature and OLEDs fabricated using TTS system have low leakage current density at reverse bias because of effective confinement of energetic particles during sputtering process.