• 한국관개배수논문집
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• 제1권2호
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• pp.11-21
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• 1994

A numerical model for conservation form of Saint Venant equations for nonprismatic channels (CFSVE model) is developed. The model is based on a finite difference solution of the Preissmann scheme. The CFSVE model consists of data pre-management program (D

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.997-1002
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• 2002

Traditional prediction models have been developed with a fixed equation form based on the limited number of data and parameters. If new data is quite different from original data, then the model should update not only its coefficients but also its equation form. However, artificial neural network (ANN) does not need a specific equation form. Instead of that, it needs enough input-output data. Also, it can continuously re-train the new data, so that it can conveniently adapt to new data. Therefore, the purpose of this paper is to develop the I-PreConS (Intelligent system for PREdiction of CONcrete Strength using ANN) that provides in-place strength information of the concrete to facilitate concrete form removal and scheduling for construction.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.681-686
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• 2000

Machining information such as machined form and surface roughness accuracy is an important factor for manufacturing precise parts. To this regard, OMM(On the Machine Measurement) has been issued for last several decades to alternate with CMM. In this research, measuring system consisting of a laser probe is developed for machined form and surface roughness measurement on the machine tool. The obtained machined form accuracy is compared with reference one defined in CAD model. The measured surface roughness data is compared with measured master surface beforehand. Furthermore, using the pre-defined volumetric error map approach compensates the geometric accuracy of the machine tool. The overall performance is compared with CMM, and verified the feasibility of the measurement system.

• 한국정밀공학회지
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• 제17권7호
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• pp.232-240
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• 2000

Machining information such as machined form and surface roughness accuracy is an important factor for manufacturing precise parts. To this regard, OMM(On the Machine Measurement) has been issued for last several decades to alternate with CMM. In this research, measuring system consisting of a laser probe is developed for machined form and surface roughness measurement on the machine tool. The obtained machined form accuracy is compared with reference one defined in CAD model. The measured surface roughness data is compared with measured master surface beforehand. Furthermore, using the pre-defined volumetric error map approach compensates the geometric accuracy of the machine tool. The overall performance is compared with CMM, and verified the feasibility of the measurement system.

• International Journal of Computer Science & Network Security
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• 제23권3호
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• pp.81-93
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• 2023

The popularity of short-form video platforms like TikTok has increased recently. Short-form videos are significantly shorter than traditional videos, and viewers regularly switch between different types of content to watch. Therefore, a successful prefetching strategy is essential for this novel type of video. This study provides a resource-effective prefetching technique for streaming short-form videos. The suggested solution dynamically adjusts the quantity of prefetched video data based on user viewing habits and network traffic conditions. The results of the experiments demonstrate that, in comparison to baseline approaches, our method may reduce data waste by 21% to 83%, start-up latency by 50% to 99%, and the total time of Re-buffering by 90% to 99%.

• Applied Microscopy
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• 제39권4호
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• pp.365-371
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• 2009

본 연구는 우주비행 훈련 중인 남녀 예비우주인의 모발을 채취하여 모발의 형태적 변화를 전자현미경을 사용하여 관찰하였고 인장강도 특성을 인장강도기를 사용하여 분석하였다. 남성과 여성 두 예비우주인의 모발 표면은 매우 거칠고 불규칙한 모양을 하고 있었다. 예비우주인들의 모발표면에는 파괴된 큐티클세포의 잔유물이 지저분하게 붙어 있었고, 비늘이 분리되어 있었다. 그리고 큐티클층을 이루고 있는 큐티클세포의 세포질에는 많은 구멍을 형성하고 있었다. 모발 표면에서 큐티클세포의 부서짐은 이들 구멍들이 형성된 부위인 내큐티클이 파괴되면서 나타났다. 그리고 여성 예비우주인 모발의 인장강도는 14.60mm로서 건강모발과 비교하였을 때 약 10% 감소한 것으로 나타났다.

• 한국위성정보통신학회논문지
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• 제3권1호
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• pp.15-21
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• 2008

OFDM (직교 주파수 분할 다중화) 신호의 높은 PAPR은 시스템의 송신단에서 전력증폭기의 비선형적 특성으로 인해 비선형 왜곡이 불가피하게 발생한다. 이 현상은 대역 내 왜곡과 대역 외 방사를 초래한다. 본 논문에서는 다항식 (polynomial) 모델에 기반한 사전왜곡(pre-distortion) 기법으로 이러한 문제를 보상하는 기법을 제안한다. 비선형 및 역비선형 다항식 모델 추정은 LSE(Least Square Error) 알고리즘으로 수행한다. 또한 시스템의 성능 향상을 위해 피크제거와 클리핑 결합기법을 이용해 OFDM 신호가 전력증폭기의 포화 영역 근처에서 동작함으로써 발생하는 왜곡된 신호의 진폭을 제거한다.

• International Journal of Fluid Machinery and Systems
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• 제1권1호
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• pp.10-23
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• 2008

The development of pre-set wavelength G$\ddot{o}$rtler vortices are studied in the boundary-layer flows on concave surfaces of 1.0 and 2.0 m radius of curvature. The wavelengths of the vortices were pre-set by thin wires of 0.2 mm diameter placed 10 mm upstream and perpendicular to the concave surface leading edge. Velocity contours were obtained from velocity measurements using a single hot-wire anemometer probe. The most amplified or dominant wavelength is found to be 15 mm for free-stream velocity of 2.1 m/s and 3.0 m/s on the concave surface of R = 1 m and 2 m, respectively. The velocity contours in the cross-sectional planes at several streamwise locations show the growth and breakdown of the vortices. Three different regions can be identified based on the growth rate of the vortices. The occurrence of a secondary instability mode is also shown in the form of mushroom-like structures as a consequence of the non-linear growth of the G$\ddot{o}$rtler vortices. By pre-setting the vortex wavelength to be much larger and much smaller than the most amplified one, the splitting and merging of G$\ddot{o}$rtler vortices can be respectively observed.

• 전기전자학회논문지
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• 제3권2호
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• pp.276-284
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• 1999

본 논문에서는 높은 자릿수를 이용하는 고속나눗셈 연산기의 성능을 향상시키는 한 방편으로, 나눗셈 연산시에 영역변환상수를 계산하지 않고 직접 검색테이블에 저장하는 방법을 제시하고자 한다. 그리고 영역변환상수 검색테이블의 크기를 줄이기 위하여 영역변환상수의 범위를 분석하여서 검색테이블의 크기를 일차적으로 줄였고, 범위를 분석한 영역변환상수를 두 개의 검색테이블로 구성하여서 이차적으로 크기를 줄었다. 제기된 방법론은 검색테이블의 크기를 줄이면서 나눗셈 연산기의 연산순환주기를 한 단계 낮출 수 있고, 연산순환주기를 감소하기 위한 기본 자릿수 선택시에 매우 유리하기 때문에 추후 다양한 응용이 기대된다.

• Steel and Composite Structures
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• 제6권5호
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• pp.401-415
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• 2006

Based on a non-linear model taking into account flexural-torsional couplings, analytical solutions are derived for lateral buckling of simply supported I beams under some representative load cases. A closed form is established for lateral buckling moments. It accounts for bending distribution, load height application and pre-buckling deflections. Coefficients $C_1$ and $C_2$ affected to these parameters are then derived. Regard to well known linear stability solutions, these coefficients are not constant but depend on another coefficient $k_1$ that represents the pre-buckling deflection effects. In numerical simulations, shell elements are used in mesh process. The buckling loads are achieved from solutions of eigenvalue problem and by bifurcations observed on non linear equilibrium paths. It is proved that both the buckling loads derived from linear stability and eigenvalue problem lead to poor results, especially for I sections with large flanges for which the behaviour is predominated by pre-buckling deflection and the coefficient $k_1$ is large. The proposed solutions are in good agreement with numerical bifurcations observed on non linear equilibrium paths.