• Advances in concrete construction
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• v.16 no.3
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• pp.155-167
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• 2023

The penetrated chloride in concrete has different behavior with mix proportions and local exposure conditions, even in the same environments, so that it is very important to quantify surface chloride contents for durability design. As well known, the surface chloride content which is a key parameter like external loading in structural safety design increases with exposure period. In this study, concrete samples containing OPC (Ordinary Portland Cement), GGBFS (Ground Granulated Blast Furnace Slag), and FA (Fly Ash) had been exposed to submerged, tidal, and splash area for 5 years, then the surface chloride contents changing with exposure period were evaluated. The surface chloride contents were obtained from the chloride profile based on the Fick's 2nd Law, and the regression analysis for them was performed with exponential and square root function. After exposure period of 5 years in submerged and tidal area conditions, the surface chloride content of OPC concrete increased to 6.4 kg/m³ - 7.3 kg/m³, and the surface chloride content of GGBFS concrete was evaluated as 7.3 kg/m³ - 11.5 kg/m³. In the higher replacement ratio of GGBFS, the higher surface chloride contents were evaluated. The surface chloride content in FA concrete showed a range of 6.7 kg/m³ to 9.9 kg/m³, which was the intermediate level of OPC and GGBFS concrete. In the case of splash area, the surface chloride contents in all specimens were from 0.59 kg/m³ to 0.75 kg/m³, which was the lowest of all exposure conditions. Experimental constants available for durability design of chloride ingress were derived through regression analysis over exposure period. In the concrete with GGBFS replacement ratio of 50%, the increase rate of surface chloride contents decreased rapidly as the water to binder ratio increased.

• Journal of Environmental Health Sciences
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• v.18 no.2
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• pp.26-38
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• 1992

This study was carried out to investigate phytoplankton distributions and water properties at 6 sampling places in Yongsan lake during the period from Jun. 30 to Nov. 17, 1991.Results obtained were as follows: 1. At sampled sites, BOD value ranges from 1.0~14.0 mg/l except Sangmongtan where it was 14.0 mg/l on Nov. 17. 2. T-N and T-P were generally high and the former was 0.26~1.42 mg/l, the latter 0.010~0.158mg/l. 3. At all sampled places, salinity was in the range of 0.04~0.57% but especially downstream of Yongsan lake was high, 0.39~0.57% on Oct. 27. 4. The phytoplankton identification in this survey period showed Cyanophyceae is 11 genera 14 species, Bacillariophyceae 13 genera 22 species, Chlorophyceae 30 genera 55 species: total 54 genera 91 species. 5. Dominant species were Anacystis aeruginosa, Lyngbya contorta, Anabeana Sp, Melosira granulata, Melosira granulata var. angustissima, Dictyosphaerium pulchellurn and Actinastrurn hantzschii var. fiuviatile during the period from summer to fall. 6. Lyngbya contorta was seemed to adapt to the circumstance of low transparency. 7. Phytoplankton distributions were seemed to be influenced by salinity and thransparency. And so they might appear much fewer in the downstream than the upperstream in Yongsan lake.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.29-33
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• 2000

The classical image reconstruction for stripmap SAR is based on the Fresnel approximation which utilizes deramping or chirp deconvolution in the synthetic aperture(slow-time) domain. Another approach in formulating stripmap SAR processing and imaging is based on the SAR wavefront reconsturction theory, and analysis of the SAR signal in the slow-time via the spherical wave Fourier decomposition of the radar radiation pattern. In this paper, we compare the Fresnel approximation and the wavefrong reconstruction methods using simulated stripmap SAR dada.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.185-192
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• 2005

Using existing static methods, it is possible to estimate accurately the reponses of structures governed by the fundamental mode. However, these methods do not provide reliable estimates for the structure where higher mode effects are significant. Parametric study was performed to analyze the dynamic characteristics of the structure with long vibration period. Based on the investigations, a new modal combination method using modal combination coefficients, Factored Modal Combination, was developed, and static earthquake load patterns addressing higher mode effects reasonably were proposed. Existing modal combination methods, such as SRSS and CQC, lack a theoretical basis to be applied to inelastic structures. In contrast, the proposed method can be applied conveniently in inelastic range as well as in elastic range.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1940-1943
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• 1998

A new PWM rectifier which offers a unity power factor is proposed. The circuit has same inductance as the conventional boosting type PWM rectifier in powering mode, but the inductance is splitted to 2 part in freewheeling mode. So the period of freewheeling mode is shorter than that of conventional boosting type PWM rectifier, and discontinuous input current is obtained in wide duty range. Therefore the proposed PWM rectifier accomplishs a unity power factor in wide range of duty ratio and boosting factor. And the conventional boosting type PWM rectifier has poor power factor near the unity boosting ratio, the proposed PWM rectifier improves this problem. The mathmatical analysis are presented and experimental results are given.

• Journal of Information Processing Systems
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• v.14 no.4
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• pp.877-891
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• 2018

In this paper, we propose a novel algorithm for rendering motion-blurred shadows utilizing a depth-time ranges shadow map. First, we render a scene from a light source to generate a shadow map. For each pixel in the shadow map, we store a list of depth-time ranges. Each range has two points defining a period where a particular geometry was visible to the light source and two distances from the light. Next, we render the scene from the camera to perform shadow tests. With the depths and times of each range, we can easily sample the shadow map at a particular receiver and time. Our algorithm runs entirely on GPUs and solves various problems encountered by previous approaches.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.120-126
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• 2011

The fatigue damages in structural details of offshore plants can be accumulated due to various environmental loadings such as swell, wave, wind and current. It is known that load histories acting on mooring and riser systems show stationary and ergodic bimodal wide-banded process. This paper provides refined approach to obtain time signals representing stress range histories from wide-banded bimodal spectrum which consists of ideally narrow-banded and fully separated two spectrums. Variations of the probabilistic characteristics for time signals according to frequency and sampling time increments are compared with the reference data to be the probabilistic characteristics such as zero-crossing period, peak period, and irregularity factor obtained from an assumed ideal spectrum. It is proved that the sampling time increment more affects on the probabilistic characteristics than frequency increment. The fatigue damages according to the frequency and sampling time increments are also compared with the ones with minimum increment condition which are thought to be exact fatigue damage. It is concluded that the maximum sampling time increment to obtain reliable time signals should be determined that ratio of applied maximum sampling time increment and minimum period is less than approximately 0.08.

• Journal of muscle and joint health
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• v.9 no.2
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• pp.166-176
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• 2002

The purpose of this study was done to identify analysis study quality of life in home stayed arthritis patients. The subject for this study were 56 arthritis patients in K city and boundary area resident, and period of data collection was from July, 2000 to November, 2000. The results are as follows. 1. Mean score of Quality of life was $171.13{\pm}44.08$(range from 66 to 244), Mean score of depression was $36.71{\pm}12.11$(range from 18 to 64), score of social support was $3.96{\pm}5.30$(range from 0 to 19), and score of stress was $322.80{\pm}34.18$(26 to 2316). 2. Main demographic factor influenced upon quality of life was age, sex, educational level and marital status, and main Physical factor influenced upon qualify of life was height, systolic and diastolic blood pressure. 3. Quality of life was correlated negatively with depression, and positively social support. 4. quality of life in home arthritic patient was explained 68% by depression, age and social support. In conclusion, nursing intervention of arthritic patient in home considers age, social support and depression in order to promote quality of life.

• The Korean Journal of Rehabilitation Nursing
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• v.7 no.2
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• pp.207-212
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• 2004

Purpose: This study was to investigate the relationship between mastery and activity of daily life in rheumatoid arthritis patients. Method: The subjects for this study were 222 patients registered in H University Hospital Rheumatoid Arthritis Center, and the period of data collection was from August 15, 2003 to September 30, 2003. Reliability coefficients of instruments were found Cronbach's Alpha =.74~.94. In data analysis, SPSSWIN 10.0 program was utilized for descriptive statistics, Pearson's correlation, and multiple regression analysis. Result: The results were as follows. 1) The range of total uncertainty scores was from 33 to 87 and the mean score of the uncertainty in rheumatoid arthritis patients was 63.27. 2) The range of total mastery scores was from 10 to 27 and the mean score of the mastery in rheumatoid arthritis patients was 18.70. 3) The range of total activity of daily life scores was from 22 to 80 and the mean score of the activity of daily life in rheumatoid arthritis patients was 72.56. 4) The level of mastery was significant correlation with activity of daily life(r=.395, p<.01).

• Wind and Structures
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• v.24 no.6
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• pp.613-635
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• 2017

Strong downslope windstorms often occur in the Liguria Region. This part of North-Western Italy is characterised by an almost continuous mountain range along its West-East axis consisting of Maritime Alps and Apennines, which separate the Padan Plain to the North from the Mediterranean Sea to the South. Along this mountain range many valleys occur, frequently perpendicular to the mountain range axis, where strong gap flows sometimes develop from the top of the mountains ridge to the sea. In the framework of the European projects "Wind and Ports" and "Wind, Ports, and Sea", an anemometric monitoring network made up of 15 (ultra)sonic anemometric stations and 2 LiDARs has been realised in the three main commercial ports of Liguria. Thanks to this network two investigations are herein carried out. First, the wind climatology and the main statistical parameters of one Liguria valley have been studied through the analysis of the measurements taken along a period of 4 years by the anemometer placed at its southern exit. Then, the main characteristics of two strong gap flows that occurred in two distinct valley of Liguria are examined. Both these studies focus, on the one hand, on the climatological and meteorological characterisation of the downslope wind events and, on the other hand, on their most relevant quantities that can affect wind engineering problems.