• 한국음향학회지
• /
• 제40권3호
• /
• pp.219-227
• /
• 2021

본 논문에서는 적으로부터 은밀히 아군에게 통신 신호를 전송하기 위해서 Orthogonal Frequency Division Multiplexing(OFDM) 기반 돌고래 휘슬음 모방 변조 기법을 제안하였다. 제안한 방법은 돌고래 휘슬음을 여러 개의 OFDM 심볼과 대응되는 시간 슬롯들로 나눈 후, 매 슬롯에서 돌고래 휘슬음이 위치한 주파수 대역을 갖는 부반송파에 Differential Phase Shift Keying(DPSK) 심볼을 매핑하여 변조한다. 제안한 방법은 기존의 Chirp Spread Spectrum(CSS)와 Frequency Shift Keying(FSK) 기반의 돌고래 휘슬음 모방 변조 기법들에서 발생하는 주파수 윤곽의 불연속성을 줄일 수 있고, 변조 차수를 증가시켜도 모방 성능 열화량이 작다는 장점이 있다. 전산 모의실험을 통해 제안 방법의 Bit Error Rate(BER)과 모방 성능이 기존의 CSS와 FSK에 비해 우수함을 보였다.

• Bulletin of the Korean Chemical Society
• /
• 제34권6호
• /
• pp.1823-1828
• /
• 2013

Tetraoxanes (1,2,4,5-tetraoxanes) have been reported to exhibit potent antimalarial activity. In the present study, the three dimensional-quantitative structure activity relationship (3D-QSAR) studies were performed on a series of tetraoxanes derivatives using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. The best predictive CoMFA model with atom fit alignment resulted in cross-validated coefficient ($q^2$) value of 0.719, non-cross-validated coefficient ($r^2$) value of 0.855 with standard error of estimate (SEE) 0.335. Similarly, the best predictive CoMSIA model was derived with $q^2$ of 0.739, $r^2$ of 0.847 and SEE of 0.344. The generated models were externally validated using test sets. The final QSAR models as well as the information gathered from 3D contour maps should be useful for the design of novel tetraoxanes having improved antimalarial activity.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.15-18
• /
• 2005

As consumer in optics, electronics, aerospace and electronics industry grow, the demand for ultra-precision aspheric surface lens increases higher. To enhance the precision and productivity of ultra precision aspheric surface micro lens, The development of ultra-precision grinding system and manufacturing properties for the aspheric surface micro lens are described. In the work reported in this paper, and ultra-precision grinding system for manufacturing the aspheric surface micro lens was developed by considering the factors affecting the surface roughness and profiles accuracy. And this paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. It results was that a form accuracy of $3\;{\mu}m$ P-V and a surface roughness of $0.1\;{\mu}m\;R_{max}$.

• 한국가구학회지
• /
• 제19권5호
• /
• pp.319-327
• /
• 2008

As art of lamination by plywood got to be generally used, it became a suitable material for expressing live curves that were not able to be expressed on wood furniture made of plank and timber, as well as, openwork deep in curved space, heavy quality of material, and changing contour line-looking wave lines with different process angles. As an alternative, it would be good to build a full scale model, since it would provide practice in form-building and it would also provide a chance to correct the form. Less material can be used and reduce the cutting process by Properly trimming models made of soft formal structure such as Styrofoam Iso-pink and adhesive Styrofoam, and separating the layers and using them on shape cutting of plywood with the same thickness. And by attaching the model veneer that was used in shape cutting of the model and using it as a cutting guide, we can reduce the error of work and successively build the planned form. Since this study is about the need of a full scale model for a laminated wood model and an efficient process, this study concentrates more on process.

• 대한전자공학회논문지SP
• /
• 제37권6호
• /
• pp.1-8
• /
• 2000

이 논문은 동영상에서 의미 있는 객체를 추적하기 위해, 첫 번째 프레임에서 사용자가 관심 대상인 객체를 정의하고, 그 다음 프레임부터 자동으로 그 객체를 추적하는 반자동 기법을 제안한다. 제안한 객체 추적 알고리즘은 객체 경계 투영, 불확실 영역 추출, 경계 재조정 단계 등 모두 세 단계로 구성되며, 첫 단계에서는 움직임 추정을 통해 이전 프레임에서 현재 프레임으로 객체를 투영하고, 두 번째 단계는 투영한 결과를 이용하여 윤곽선 부근에서 투영이 불확실한 영역을 MC 오류 및 색채 유사성 검사를 거쳐 추출하며, 마지막으로 투영이 불확실한 영역을 재조정함으로써 정확한 객체의 경계를 찾는다. 모의 실험을 통해 제안한 알고리즘이 기존의 반자동 알고리즘에 비해 다양한 영상에 대해 만족할 만한 결과를 보임을 확인하였다.

• 한국정보처리학회논문지
• /
• 제4권2호
• /
• pp.586-595
• /
• 1997

본 논문에서는 프렉탈과 신경망을 이용하여 등고선 데이타로부터 3차원 지형을 복원하는 더욱 개선된 알고리즘을 제안한다. 본 알고리즘은 이미 제안한 것[1, 2, 3]을 바탕으로 인접 패치들과의 관계를 고려하여 개선한 것으로, 지형의 특징을 좀더 사실 적으로 반영할 수 있는 더 많은 조건을 부여한 데이타를 기존의 특징 데이타에 부가하여 학습한다. 학습 결과 평균오차가 줄어든 학습 패턴을 이용하여 산악지형과 평탄지형 에 대하여 실험하고 결과 산악지형에 대한 적용이 더 효과적임을 보였다.

• International Journal of Precision Engineering and Manufacturing
• /
• 제8권2호
• /
• pp.59-63
• /
• 2007

We propose a controller design analysis for a cross-coupling control system, which is essential for achieving high contouring accuracy in multi-axis CNC systems. The proposed analysis combines three axial controllers for each individual feed drive system together with a cross-coupling controller at the beginning of the design stage in an integrated manner. These two types of controllers used to be separately designed and analyzed since they have different control objectives. The proposed scheme is based on a mathematical formulation of a three-dimensional contour error model and includes a stability analysis for the overall control system and a performance analysis in terms of contouring and tracking accuracy at steady state. A computer simulation was used to demonstrate the validity of the proposed methodology. The performance variation was investigated under different operating conditions and controller gains, and a design range was elicited that met the given performance specifications. The results provide basic guidelines in systematic and comprehensive controller designs for multi-axis CNC systems. A cross-coupling control system was also implemented on a PC-based three-axis CNC testbed, and the experimental results confirmed the usefulness of the proposed control system in terms of contouring accuracy.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 B
• /
• pp.1266-1268
• /
• 1996

In this study an automatic roiling-coli labeling system using robot vision system and peripheral mechanism is proposed and implemented, which instead of the manual labor to attach labels Rolling-coils in a steel miil. The binary image process for the image processing is performed with the threshold, and the contour line is converted to the binary gradient which detects the discontinuous variation of brightness of rolling-coils. The moment invariants algorithm proposed by Hu is used to make it easy to recognize even when the position of the center are different from the trained data. The position error compensation algorithm of six degrees of freedom industrial robot manipulator is also developed and the data of the position of the center rolling-coils, which is obtained by floor mount camera, are transfered by asynchronous communication method. Therefore even if the position of center is changed, robot moves to the position of center and performs the labeling work successfully. Therefore, this system can be improved the safety and efficiency.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.804-806
• /
• 2003

Probable Maximum Precipitation (PMP) is essential in the design of hydraulic structures such as dams, weirs and flood control structures. Up to the present, PMP has been derived from any proper single storm which can have a large error. PMP values should be evaluated from many historic heavy storm events from all over the country. Since this can be done at the spots of storm occurring and the calculated PMP from all spots in the country can be correlated. The objectives of this study are therefore to evaluate PMP from historic heavy storm data from 1972 to 2000 by using meteorological method, then to correlate and to present the results using GIS. The maximized rainfall depths can be calculate from depth of heavy rainfall and dew point temperature, and then can be analyzed for each rainfall duration to obtain spatial rainfall distribution by using GIS. The depth-area-duration relationship of maximized rainfall can be obtained and this helps to develop enveloped curves . The results from this study are a set of contour maps of PMP for each rainfall duration for all over the country and the depth-area-duration relationships for the area of 100 to 50,000 km.$^{2}$ at duration of 1, 2 and 3 days.

• 대한방사선치료학회지
• /
• 제32권
• /
• pp.31-39
• /
• 2020

목 적: 본 연구는 HalcyonTM과 TrueBeamTM에서 사용하는 6MV-FFF(Flattening Filter Free) 에너지를 이용하여 전산화치료계획시스템(Treatment Planning System, TPS)에서 계산된 선량과 광자극형광선량계(Optically Stimulated Luminescence Dosimeter, OSLD)로 측정된 표재 선량(Superficial dose)을 비교하고자 한다. 재료 및 방법: 팬텀연구를 위해 인체모형 팬텀(Human Phantom)의 CT 영상을 이용하여 치료계획시스템에서 성문암(Glottic cancer)과 유사한 치료계획용적(Planning Target Volume, PTV)과 두경부위의 등 중심점(Iso-center) 위치에 측정을 위한 Point(M), Point(R), Point(L)의 구조물을 설정하고 체표윤곽(Body contour)에 5mm Bolus를 적용하였다. 그 후 전산화치료계획은 HalcyonTM과 TrueBeamTM의 6MV-FFF 에너지를 이용하여 정적(Static) 세기변조방사선치료(Intensity Modulated Radiation Therapy, IMRT)와 용적변조회전치료(Volumetric Modulated Arc Therapy, VMAT)계획을 각각 수립하였다. 전산화치료계획과 동일하게 재현하기 위해 OSLD를 등 중심점에 위치시키고 5mm Bolus를 적용하여 선량 전달 후 오차율을 비교하였다. 결 과: 인체모형 팬텀을 사용한 실험 결과 HalcyonTM의 전산화치료계획시스템에서의 점 선량과 OSLD를 이용한 선량 측정의 오차율의 절댓값의 평균은 VMAT, IMRT 각각 1.7±1.2%, 4.0±2.8%로 확인되었으며, TrueBeamTM의 오차율의 절댓값의 평균은 VMAT, IMRT 각각 2.4±0.4%, 8.6±1.8%로 확인되었다. 결 론: 실험결과 HalcyonTM을 기준으로 TrueBeamTM에서 VMAT과 IMRT 각각 2.4배, 3.6배 더 큰 오차가 발생하는 것을 확인할 수 있었다. 따라서 본 연구의 결과를 토대로 표재 선량에 대한 정확한 선량평가가 이루어져야 하는 경우, TrueBeamTM보다 HalcyonTM에서 정확한 선량 평가가 이루어질 수 있을 것으로 사료된다.