• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.3-8
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• 2010

This paper present the results of investigation on the use of rice husk ash as a partial substitute for cement in construction. One hundred and eighty specimens of concrete cubes were cast. 0, 5, 10, 15, and 20% partial replacement of cement with rice husk ash were carried at 1:2:4 mixes by weight with 0.60, 0.65, 0.70 water/cement ratio. The results indicated that compressive strengths of cubes at 0.6, water/cement were higher than 0.65 and 0.70. Also 5% partial replacement cement with rice husk ash at $28^{th}$ day average compressive strength value of $25.4\;N/mm^2$ compared well with 0% partial replacement of cement with rice husk ash of $26.28\;N/mm^2$. This shows that at 5% partial replacement of cement with rice husk ash can be used for structural concrete and at 15% replacement or more it can be used for non - structural construction works or light weight concrete construction. The cost analysis shows substantial amount of savings for the country.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.68-76
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• 2015

Phase-change memory (PCM) is a promising technology that is anticipated to be used in the memory hierarchy of future computer systems. However, its access time is relatively slower than DRAM and it has limited endurance cycle. Due to this reason, PCM is being considered as a high-speed storage medium (like swap device) or long-latency memory. In this paper, we adopt PCM as a virtual memory swap device and present a new page replacement policy that considers the characteristics of PCM. Specifically, we aim to reduce the write traffic to PCM by considering the dirtiness of pages when making a replacement decision. The proposed replacement policy tracks the dirtiness of a page at the granularity of a sub-page and replaces the least dirty page among pages not recently used. Experimental results with various workloads show that the proposed policy reduces the amount of data written to PCM by 22.9% on average and up to 73.7% compared to CLOCK. It also extends the lifespan of PCM by 49.0% and reduces the energy consumption of PCM by 3.0% on average.

• Journal of radiological science and technology
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• v.22 no.1
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• pp.21-26
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• 1999

To make a comparative analysis for clinical application of total hip replacement arthroplasty(THRA) using fluoroscopy, we have performed total hip replacement arthroplasty making 30 patients an object with general radiography and fluoroscopy respectively. The results are as follows : 1) Reexamination rate was 80% of patients and mean 3.9 sheets in the general radiography, where as it was 46.7% and 0.37 sheets in the fluoroscopy(p<0.01) 2) Add examination was 2 cases in the general radiography, but fluoroscopy was no add examination. 3) The total film sheet used was mean 10.16 in the general radiography and 6.73 in the fluoroscopy. 4) In the cause of reexmination and add examination, inaccurate position of patient accounted for 72.6% in the general radiography and poor exposure condition accounted for 45.5% in the fluoroscopy. Total hip replacement arthroplasty using the fluoroscopy decreased reexamination and add examination rate, for these reasons, this method was effective abatement of pain, exposured radiation dose, and examination time and so on.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.51-58
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• 2015

Intelligent distribution automation system includes operating a switchgear of distribution system remotely when switchgear are not available to operate quickly. This system makes it possible to reduce the interrupt time. It also aims to improve the reliability of customers. Currently, Intelligent distribution automation improves the reliability by replacing manual switchgear, which is installed as sectional switchgear. However the prioritization of the replacement for the switchgear is required for its intellectualization. Many studies have been conducted related with prioritization of switchgear replacement. But it is difficult to interpret and apply to the power distribution system. That is because most of the studies just considers customer numbers for prioritizing the replacement. In this paper presents an algorithm to determine the intelligent swichgear replacement priority considering customer number, load quantity and interruption cost. Further, this algorithm is verified by using system reliability index.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.443-452
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• 2005

The compaction pile methods with low replacement area ratio used sand(SCP) or gravel(GCP) has been usually applied to improvement of soft clay deposits. In order to design accurately compaction pile method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP and GCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which and elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And,through the results of the numerical analyses, each mechanical behaviors of compaction piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between compaction piles and clays.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.37-49
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• 2012

PURPOSES : This study is to investigate the fundamental properties of limestone added cement concrete for application of pavement. METHODS : As the production of Portland cement causes environmental problems, engineers have sought more environment-friendly concrete construction materials. Limestone powder can be used for concrete as a partial replacement of Portland cement. One of the great applications of limestone powder added cement concrete might be a cement concrete pavement since the concrete pavement consumes massive quantity of Portland cement. Experimental variables were different replacement level of limestone powder by 0% to 25% with 5% increment. Before hardening of fresh concrete, setting time and plastic shrinkage characteristics were investigated in addition to other basic properties. Properties of hardened concrete included compressive, tensile and flexural strength as well as drying shrinkage. RESULTS : The addition of limestone powder did not significantly affect the properties of fresh concrete. Strength deceased as the replacement ratio increased and when the replacement ratio was greater than 10% decrease rate increased. CONCLUSIONS : It was found that the partial replacement of the limestone powder to cement in pavement materials can be positively considered as its mechanical properties show comparable performance to those normal concrete.

• Journal of Chest Surgery
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• v.11 no.2
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• pp.213-226
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• 1978

One hundred cases of open heart surgery were done at this Department in 1977. There were 65 congenital anomaly and 35 acquired diseases. Out of 65 cases of congenital malformation 35 acyanotic and 30 cyanotic cases were found. Fifteen cases of ventricular septal defect and 29 tetralogy of Fallot were noted eight patients expired out of 65 congenital anomaly [12.3%] , 4 out of 35 acyanotic [11. 4%] and 4 among 30 cyanotic anomaly[13.3%]. Among 35 cases of acquired heart disease 3 atrial myxoma [2 left and one right] and 32 valvular lesions were noted. In two cases open mitral commissurotomy, and in 30 valve replacement were done. Twenty-two single valve and 8 double valve replacement were done. Seven patients expired out of 30 patients [23.3%]. Among 22 single valve replacement cases 2 and among 8 double valve 5 died. ~ In eighteen mitral valve replacement cases 2 deaths occurred. One mitral insufficiency patient who expired suffered from severe pulmonary` hypertension [PA=120/67mmHg], tricuspid insufficiency and a large ventricular septal defect. The patient underwent mitral valve replacement, tricuspid annuloplasty and patch closure of ventricular septal defect. Over all mortality rate for 100 open heart surgery cases was 15%. Since 1977 open heart surgery cases were done routinely in this institution and cases are increasing rapidly. With present rapid improvement of economical status and introduction of medical insurance system, open heart surgery will be firmly established in Korea in the very near future.

• Journal of Chest Surgery
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• v.12 no.4
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• pp.355-360
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• 1979

Mitral and aortic valve replacement with tricuspid annuloplasty was undertaken in 5 patients out of 38 valvular surgery between the period from Jan. 1977 to May 1979 in the Dept. of Thoracic and Cardiovascular Surgery in Korea University Hospital. All were male patients with age ranging from 18 to 42 years, and preoperative evaluation revealed one case in Class IV, and four cases in Class III according to the classification of NYHA. Preoperative diagnosis was confirmed by routine cardiac study including retrograde aorto- and left ventriculography, and there were two cases with MSi+ASi+Ti, two cases with MSi+Ai+Ti, and one case with Mi+Ai+Ti. Double valve replacement was performed under the hypothermic cardiopulmonary bypass with total pump time of 247 min. in average ranging from 206 min. to 268 min. During aortic valve replacement, left coronary perfusion was done in the first two cases, and cardiac arrest with cardioplegic solution proposed by Bretschneider was applied in the remained three cases. Starr-Edwards, Bjork-Shiley prosthetic valves and Carpentier-Edwards tissue valve were replaced in the aortic area, and Carpentier-Edwards and Angell-Shiley tissue valves were replaced in the mitral area with each individual combination [three prosthetic and two tissue valves in the aortic, and five tissue valves in the mitral area respectively]. Postoperative recovery was uneventful in all cases except one case with hemopericardium, which was managed with pericardiectomy on the postoperative 10th day in good result. Follow-up after double valve replacement of the all five cases for the period from 6 months to 33 months revealed satisfactory adaptation in social activity and occupation with cardiac function of Class I according to the classification of NYHA In all five cases.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.2
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• pp.150-161
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• 2015

This paper proposes a new approach to technology valuation, the market-replacement cost approach which integrates the cost-based approach and market-based approach. The proposed approach estimates the market-replacement cost of a target technology using R&D costs of similar R&D projects previously conducted. Similar R&D projects are extracted from project database based on document similarity between project proposals and technology description of the target technology. R&D costs of similar R&D projects are adjusted by mirroring the rate of technological obsolescence and inflation. Market-replacement cost of the technology is then derived by calculating the weighted average of adjusted costs and similarity values of similar R&D projects. A case of "Prevention method and system for the diffusion of mobile malicious code" is presented to illustrate the proposed approach.

• Journal of Chest Surgery
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• v.27 no.7
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• pp.581-586
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• 1994

From February 1985 to February 1993, 18 operations were performed in 17 patients for treatment of aneurysmal disease [n=12] and/or dissection of the ascending aorta [n=6]. The ages ranged from 26 to 69 years [mean 44.3 $\pm$ 11.0 years].The proposed operations include composite graft replacement of aortic valve and ascending aorta with coronary reimplantation in 11, graft replacement of ascending aorta alone in 5, aortic valve replacement and supracoronary graft replacement in 1 and ascending aorta to abdominal aorta bypass with thromboexclusion of descending aorta in one patient. Both Bentall [n=6] and Cabrol [n=5] technique were utilized for reimplantation of coronary arteries.Concomitant replacement of aortic arch and arch vessel reconstruction was necessary in two patients. Hypothermic circulatory arrest was utilized in 6 patients. Recently, four patients were managed on warm blood continuous cardioplegia via retrograde route. There were no operative deaths. No significant postoperative complications were noted. Postoperative follow up was complete in 15 patients from 1 month to 72 months. Redo operation was necessary in one patient who had suffered from distal recurrence of dissection 5 years after successful Bentall operation. The other patients are all in excellent clinical condition. From our early experience with those 17 cases, we assume that satisfactory operative result could be achieved with a variety of surgical technique including hypothermic circulatory arrest. In addition, continuous perfusion of warm blood cardioplegia via retrograde route is supposed to be beneficial in selected cases.