• Journal of Communications and Networks
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• 제11권1호
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• pp.42-46
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• 2009

Superimposed training (SIT) design for estimating of time-varying multipath channels is investigated for mobile orthogonal frequency division multiplexing (OFDM) systems. The design of optimum SIT consists of two parts: The optimal SIT sequence is derived by minimizing the channel estimates' mean square error (MSE); the optimal power allocation between training and information data is developed by maximizing the averaged signal to interference plus noise ratio (SINR) under the condition of equal powered paths. The theoretical analysis is verified by simulations. For the metric of the averaged SINR against signal to noise ratio (SNR), the theoretical result matches the simulation result perfectly. In contrast to an interpolated frequency-multiplexing training (FMT) scheme or an SIT scheme with random pilot sequence, the SIT scheme with proposed optimal sequence achieves higher SINR. The analytical solution of the optimal power allocation is demonstrated by the simulation as well.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1224-1227
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• 2009

When evaluating the quality of images and displays, it is important to combine the characteristics as perceived by the human visual system and measured by equipment using subjective and objective methods, respectively. In the case of objective methods, the quality of a display is measured using colorimetric or radiometric devices according to existing standards covering the color temperature, gamut size, gamma characteristic, and device characterization. Meanwhile, subjective methods assess the quality of an image using the human visual system based on a comparison with a reference or counterpart using such metrics as the sharpness, noise, contrast, saturation, and color accuracy. Objective and subjective methods are usually used together in comparison, as ultimately it is observers watching images on a display. In addition to existing objective methods, a new image quality metric is also introduced as regards the JPEG compression ratio that is reflected in the relationship between the gamut size and the color fidelity in CIELAB color space.

• 한국광학회지
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• 제11권2호
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• pp.85-90
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• 2000

CRT디스플레이의 화질 평가에는 위도, 콘트라스트, addressability, 시청거리 등의 다양한 물리적 특성치가 사용된다. 그러나, 최종적인 CRT디스플레이 화질의 비교·평가는 물리적 특성치가 아닌 실제 사용자가 느끼는 화질 즉, 주관적 인지 화질에 의해 이루어진다. 본 논문에서는 4종류 CRT모니터의 SQRI(SQuare Root Integral) 값과 다수의 피험자에 의한 주관적 화질 평가 점수와의 상관성이 비교되었다. 그리고, 이러한 SQRI법의 주관적 화질 평가 척도로서의 타당성을 바탕으로 모니터의 다양한 물리적 특성치가 주관적 화질에 미치는 영향이 검토되었다.

• Nutritional Sciences
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• 제2권2호
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• pp.93-101
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• 1999

The aim of this study was to investigate influence of body build on body composition, energy metabolic state and insulin concentration of blood. 29 male athletes and 36 male non-athletic students were recruited for the study. Anthropometry including chest depth and breadth, fat mass, fat fee mass, tricep skinfold thickness were measured. fasting glucose, lactate, triglyceride, fee fatty acid, and insulin concentration in serum were measured . Body build was assessed using metric index, which calculated by regression equations of Mohr and Greil. The athletic and non-athletic students were allocated to 3 body build, that is leptomorph, mesomorph, and pyknomorph. Resting metabolic rate was calculated. Respiratory quotient was determined through ratio of measured VO$_2$, and V$CO_2$. Most non-athletes have a leptomorphic body build, in contrast to athletes mesomorphic type. The body build type influenced body composition differently between non-athletic group and athletic group. Weight, body mass index, body fat mass and fat mass proportion (%), and fat-free mass increased from leptomorph to pyknormorph in non-athletic group. Pyknormorphic athletes have a significant higher body mass index, fat mass, fat free mass than other body build type. Serum glucose, triglyceride, lactate, insulin showed significant differences only in non-athletic group between leptomorph and mesomorph. RMR increased significantly from leptomorph to mesomorph in non-athletes. There was no significant difference of RQ among 3 body build types in both athletes and non-athletes. This study gives a coherent data on body build and body composition for athletes and non-athletes students. The influence of body builds on energy metabolic status of serum was different between athletes and non-athletes.

• Advances in concrete construction
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• 제17권2호
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• pp.93-110
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• 2024

The process of concrete production consumes an immense volume of water, with approximately one billion metric tons of freshwater being utilized for tasks such as aggregate washing, fresh concrete production, and concrete curing. The accessibility of clean water for the public is hindered by the limited availability of water resources, primarily due to the rapid expansion of industries such as tanneries, stone quarries, and concrete manufacturing. These industries not only consume substantial amounts of freshwater but also generate significant volumes of various types of waste. Therefore, the use of fresh water in concrete production should be minimized. Few studies have reviewed the production of concrete using wastewater to derive practical and applicable findings for the industry. Thus, this study thoroughly explores the physical and chemical effects of wastewater on concrete, examining aspects like durability, hardened properties, and rheological characteristics. It identifies key factors that can compromise concrete properties when exposed to wastewater. The scarcity of research on integrating wastewater into concrete production underscores the urgent necessity for innovative approaches and methodologies in this field. While the inclusion of wash water typically reduces the workability of fresh concrete, it often enhances its compressive strength. Notably, significant improvements have been observed when using tertiary processed wastewater, wash water, polyvinyl alcohol-based wash water (PVAW), and reclaimed water in the concrete mixing process. The application of tertiary treatment to wastewater resulted in a notable enhancement of compressive strength, showing increases of up to 7%. In contrast, wastewater treated through secondary methods experienced a decline in strength ranging from 9% to 18% over a period of six months. However, the use of reclaimed wastewater demonstrated an improvement in strength by 8% to 17%, depending on the concentration level ranging from 25% to 100%. In contrast, the utilization of secondary processed wastewater and industrial water has a minimal impact on the concrete's strength.

• 환경영향평가
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• 제21권3호
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• pp.483-501
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• 2012

본 연구에서는 2005 - 2006년 기간 동안 국내 인공호의 환경영향평가를 위해 LEHA 다변수 생태모형(Lentic Ecosystem Health Assessment Model)을 청평호에 적용하였고, 생태 건강도 모델값을 산정하였다. LEHA 생태 평가모형은 생물학적 변수($B_p$), 물리적 변수($P_p$), 화학적 변수($C_p$)의 11개 주요 메트릭으로 구성되었고, 이를 통합하여 생태 건강도 등급을 평가하였다. 생물학적 변수($B_p$)는 수환경의 질적 저하에 따라서 감소하는 민감종 메트릭($M_2$, NSS) 및 충식종 메트릭($M_5$, % $I_n$)이 이용되었고, 두 메트릭 모델값은 각각 1.5%, 32.4%로서 낮게 나타났다. 반면, 내성종($M_3$, % $T_s$)과 잡식종 메트릭($M_4$, % $O_m$) 값은 43%, 62%로서 높게 나타나 호수생태계의 질적 저하가 확인되었다. 물리적 서식지 변수($P_p$)는 수변 식피율($M_9$, % $V_c$)로서 1차 조사에 비해 2차 조사에 높게 나타났으며, 상류에서 하류로 갈수록 메트릭 모델 값이 감소하는 것으로 나타났다. 이는 정수역의 증가로 서식환경의 단순화와 인근 수체에서 실시되고 있는 잦은 골재 채취로 인한 서식지의 하상구조 변경이 악영향을 준 것으로 사료되었다. 한편, 화학적 수질특성 변수($C_p$)는 수체의 이온(양이온/음이온) 특성을 나타내는 전기전도도($M_{10}$, $C_I$)와 부영양 상태를 평가하는 Chl-a의 부영양화 지수($M_{11}$, $TSI_{CHL}$)로서 메트릭 모델값은 계절별 변이는 크게 나타났고, 지점 간의 공간변이는 미미한 것으로 나타나, "양호상태"로 평가되었다. LEHA 다변수 모델에 의거한 청평호의 환경영향평가에 의하면, 생태 건강도 LEHA 모델값은 1차 조사에서 30.7로 "보통-악화상태", 2차 조사에서 28로 "악화상태"를 보여 계절 변이 특성을 보였다. 지점별 LEHA 모델값은 호수의 정수대(S5)에서 28로 최소치를 보였고, 그 외 지점들도 29 - 30으로 지점 간 미미한 차이를 보였다. 청평호의 종합적인 환경영향평가에 의하면, 이 화학적인 수질기준 측면에서는 "양호상태"를 보인 반면, 생물학적 기준에서는 "악화상태"를 보였는데, 이는 빈번한 준설작업으로 인한 물리적 서식지 교란이 영향을 준 것으로 사료되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.907-923
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• 2020

For the severe haze situation in the Beijing-Tianjin-Hebei region, conventional fine particulate matter (PM2.5) concentration prediction methods based on pollutant data face problems such as incomplete data, which may lead to poor prediction performance. Therefore, this paper proposes a method of predicting the PM2.5 concentration based on image analysis technology that combines image data, which can reflect the original weather conditions, with currently popular machine learning methods. First, based on local parameter estimation, autoregressive (AR) model analysis and local estimation of the increase in image blur, we extract features from the weather images using an approach inspired by free energy and a no-reference robust metric model. Next, we compare the coefficient energy and contrast difference of each pixel in the AR model and then use the percentages to calculate the image sharpness to derive the overall mass fraction. Furthermore, the results are compared. The relationship between residual value and PM2.5 concentration is fitted by generalized Gauss distribution (GGD) model. Finally, nonlinear mapping is performed via the wavelet neural network (WNN) method to obtain the PM2.5 concentration. Experimental results obtained on real data show that the proposed method offers an improved prediction accuracy and lower root mean square error (RMSE).

• 국제초고층학회논문집
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• 제8권2호
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• pp.117-123
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• 2019

Tall buildings are prone to wind-induced vibrations due to their slenderness whereby peak structural accelerations may be higher than the recommended maximum value. The common countermeasure is the installation of a tuned mass damper (TMD) near the highest occupied floor. Due to the extremely large modal mass of tall buildings and because of the narrow to broad band type of wind excitation the TMD mass may become inacceptable large - in extreme cases up to 2000 metric tons. It is therefore a need to develop more efficient TMD concepts which provide the same damping to the building but with reduced mass. The adaptive TMD concept described in this paper represents a solution to this problem. Frequency and damping of the adaptive TMD are controlled in real-time by semi-active oil dampers according to the actual structural acceleration. The resulting enhanced TMD efficiency allows reducing its mass by up to 20% compared to the classical passive TMD. The adaptive TMD system is fully fail-safe thanks to a smart valve system of the semi-active oil dampers. In contrast to active TMD solutions the adaptive TMD is unconditionally stable and its power consumption on the order of 1 kW is negligible small as controllable oil dampers are semi-active devices. The adaptive TMD with reduced mass, stable behavior and lowest power consumption is therefore a preferable and cost saving damping tool for tall buildings.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권1호
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• pp.53-61
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• 2021

Distribution of fish community depends largely on environmental disturbance such as habitat change. In this study, we evaluated the impact of environmental variables and microhabitat patch types on fish distribution in Yudeung Stream at 15 sites between early May and late June 2019. We used non-metric multidimensional scaling to examine the distribution patterns of fish in each site. Gnathopogon strigatus, Squalidus gracilis majimae, Zacco koreanus, and Zacco platypus were associated with riffle and boulder areas, whereas Iksookimia koreensis, Acheilognathus koreensis, Coreoleuciscus splendidus, Sarcocheilichthys nigripinnis morii, and Odontobutis interrupta were associated with large shallow areas. In contrast, Cyprinus carpio, Carassius auratus, Lepomis macrochirus, and Micropterus salmoides were found at downstream sites associated with large pool areas, sandy/clay-bottomed areas, and vegetated areas. On the basis of these results, we suggest that microhabitat patch types are important in determining the diversity and abundance of fish communities, since a mosaic of different microhabitats supports diverse fish species. As such, microhabitat patches are key components of freshwater stream ecosystem heterogeneity, and a suitable patch composition in stream construction or restoration schemes will support ecologically healthy food webs.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4591-4596
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• 2023

Single-photon emission computed tomography SPECT image reconstruction methods have a significant influence on image quality, with filtered back projection (FBP) and ordered subset expectation maximization (OSEM) being the most commonly used methods. In this study, we proposed newly-designed adaptive non-blind deconvolution with a structural similarity (SSIM) index that can take advantage of the FBP and OSEM image reconstruction methods. After acquiring brain SPECT images, the proposed image was obtained using an algorithm that applied the SSIM metric, defined by predicting the distribution and amount of blurring. As a result of the contrast to noise ratio (CNR) and coefficient of variation evaluation (COV), the resulting image of the proposed algorithm showed a similar trend in spatial resolution to that of FBP, while obtaining values similar to those of OSEM. In addition, we confirmed that the CNR and COV values of the proposed algorithm improved by approximately 1.69 and 1.59 times, respectively, compared with those of the algorithm involving an inappropriate deblurring process. To summarize, we proposed a new type of algorithm that combines the advantages of SPECT image reconstruction techniques and is expected to be applicable in various fields.