• Journal of the Korea Institute of Building Construction
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• v.15 no.3
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• pp.281-289
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• 2015

Carbonation of concrete causes reduction of pH and subsequently causes steel corrosion for reinforced concrete structure. However, for plain concrete structure or PC product, it can lead to a decrease in porosity, high density, improvement of concrete, shrinkage-compensation. Recently, based on this theory, research of $CO_2$ curing effect has been performed, but it was mainly focused on its effects on compressive strength using only ordinary portland cement. Researches on $CO_2$ curing effect for concrete containing $CO_2$ reactive materials such as ${\gamma}-C_2S$, MgO haven't been investigated. Therefore, this study has performed experiments under water-binder ratio 40%, and the replacement ratios of ${\gamma}-C_2S$ and MgO were 90%. Micro-chemical analysis, measurement of compressive strength according to admixtures and $CO_2$ curing were investigated. Results from this study revealed that higher strength was measured in case of $CO_2$ curing compared with none $CO_2$ curing for plain specimen indicating difference between 1.08 and 1.26 times, in case of ${\gamma}-C_2S$ 90, MgO 90 specimen, incorporating high volume replaced as much as 90%, it was proven that when applying $CO_2$ curing, higher strength which has difference between 14.56 and 45.7 times, and between 6.5 and 10.37 times was measured for each specimen compared to none $CO_2$ curing. Through micro-chemical analysis, massive amount of $CaCO_3$, $MgCO_3$ and decrease of porosity were appeared.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.155-163
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• 1995

The primary purpose of this study is to hvestigate reusal techniques of high calclun-i fly ash in the construct.ion field, which may contribute to the savings of construction materials and consenratlng environment. Furt.hcrrnore, it can setup material properties or characteristics requiremi for development of new materials. Firstly, chemical and physical cahraci.eristics of liigh~calciurn fly ash is arialyseti. And then, the usability of the concrete is tcsted by investigating the flowablility and strength development through parameters of various replace ment r,itios with respect to different nuxing conditions. Finally, the durability and mechanical properties(e1astic nlodulus of the concrete is tested. As the result of the study, the following conclusions are derived : (1) the quaritii y of the CaO The primary purpose of this study is to hvestigate reusal techniques of high calclun-i fly ash in the co:lstruct.ion field, which may contribute to the savings of construction materials and consenratlng environment. Furt.hcrrnore, it can setup material properties or characteristics requiremi for development of new materials. Firstly, chemical and physical cahraci.eristics of liigh~calciurn fly ash is arialyseti. And then, the usability of the concrete is tcsted by investigating the flowablility and strength development through parameters of various replace ment r,itios with respect to different nuxing conditions. Finally, the durability and mechanical properties(e1astic nlodulus of the concrete is tested. As the result of the study, the following conclusions are derived : (1) the quaritii y of the CaO

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.109-114
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• 2015

Recently, numerous studies were dedicated on the HVFA concrete using high volume CCPs. In initial studies, main topics are dependent on material properties of HVFA concrete, but several studies were dedicated on the structural behavior of HVFA concrete such as elasticity modulus, stress-strain relationship and structural behavior nowadays. Therefore, in this paper, on the basis of recent studies on the structural behavior, 2 large-scale test members were manufactured with 7.5m span length and fly ash replacement ratio 50%, concrete compressive strength 50MPa in order to apply to the practical structure and evaluate possibility of application. From the test results, although there were small differences between test results and existing research results on the stress-strain relationship, the application to practical structure is not hard. In flexural test, as the produced pattern of displacement and strain were similar to those of general concrete without fly ash, the difference between 50% fly ash concrete and general concrete is very small. And the concrete shear strength obtained by test was similar to that of design code, so existing design code will be also able to apply.

• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.431-438
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• 2007

RFID system is core technology that construct ubiquitous environment for replacement of barcode technology. Use ratio of RFID system rapidly increase because the technology has many good points such as identification speed, storage space, convenience etc. But low-cost tag operates easily by query of reader, so the system happened user privacy violent problem by tag information exposure. The system studied many ways for security application, but operation capability of low-cost tag is about $5K{\sim}10K$ gates, but only $250{\sim}3K$ gates allocated security part. So it is difficult to apply security to the system. Therefore, this scheme uses dividing 64 bits and reduces arithmetic, so proposed scheme provide mutual authentication that can apply to low-cost RFID system. Existing methods divide by 4 and used 96 bits. However, that reduces 32 bits length for lightweight and reduced from communication number of times of 7 times to 5 times. Also, because offer security by random number than existing scheme that generate two random numbers, that is more efficient. However, uses hash function for integrity that was not offered by XOR arithmetic and added extension of proposed scheme. Extended scheme is not offered efficiency than methods that use XOR arithmetic, but identification distance is mode that is proposed secure so that can use in for RFID system.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.127-136
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• 2005

This paper measured a proper ratio of the size of demand fetch cache $L_1$ to that of prefetch cache $L_P$ by imulation when the size of $L_1$ and $L_P$ are constant which organize space-limited level 1 cache of a single microprocessor chip. The analysis of our experiment showed that in the condition of the sum of the size of $L_1$ and $L_P$ are 16 KB, the level 1 cache organization by constituting $L_P$ with 4 KB and employing OBL and FIFO as a prefetch technique and a cache replacement policy respectively resulted in the best performance. Also, this analysis showed that in the condition of the sum of the size of $L_1$ and $L_P$ are over 32 KB, employing dynamic filtering as prefetch technique of $L_P$ are more advantageous and splitting level 1 cache by constituting $L_1$ with 28 KB and $L_P$ with 4 KB in the case of 32 KB of space are available, by constituting $L_1$ with 48 KB and $L_P$ with 16 KB in the case of 64 KB elicited the best performance.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.13-24
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• 2009

This study developed a high strength and performance concrete pavement material with low shrinkage and reflection of sunlight. Based on the literature review, a new mix-design of applying flash ash to improve the strength and performance of the concrete as well as to reduce the dry shrinkage is suggested. In addition, adding black pigment to reduce the reflection and technique of applying OAG (Optimized Aggregate Gradation) is also included. The result of the laboratory experiment indicates that the brightness and the reflection, which depends on the ratio of black pigment addition, did not deviate from the normal range. When OAG is considered for the mix-design, the strength and performance of the concrete improved greatly. In addition, the mix-design using fly ash reduced the dry shrinkage of concrete and improved the resistance to the permeation of chloride ion. Furthermore, the mix-design, which uses fly ash (25% replacement) and black pigment (3% addition) with the application of OAG, is found to be the most effective mix to reduce the shrinkage and reflection as well as improving the strength and performance of the concrete. The result of an economic analysis indicates that the initial construction cost of this proposed mix is more expensive than that of normal concrete pavement material. However, it can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Journal of Chest Surgery
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• v.47 no.3
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• pp.255-261
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• 2014

Background: To determine the predictors of clinical outcomes following surgical descending thoracic aortic (DTA) repair. Methods: We identified 103 patients (23 females; mean age, $64.1{\pm}12.3$ years) who underwent DTA replacement from 1999 to 2011 using either deep hypothermic circulatory arrest (44%) or partial cardiopulmonary bypass (CPB, 56%). Results: The early mortality rate was 4.9% (n=5). Early major complications occurred in 21 patients (20.3%), which included newly required hemodialysis (9.7%), low cardiac output syndrome (6.8%), pneumonia (7.8%), stroke (6.8%), and multi-organ failure (3.9%). None experienced paraplegia. During a median follow-up of 56.3 months (inter-quartile range, 23.1 to 85.1 months), there were 17 late deaths and one aortic reoperation. Overall survival at 5 and 10 years was $80.9%{\pm}4.3%$ and $71.7%{\pm}5.9%$, respectively. Reoperation-free survival at 5 and 10 years was $77.3%{\pm}4.8%$ and $70.2%{\pm}5.8%$. Multivariable analysis revealed that age (hazard ratio [HR], 1.10; 95% confidence interval [CI], 1.05 to 1.15; p<0.001) and left ventricle (LV) function (HR, 0.88; 95% CI, 0.82 to 0.96; p<0.003) were significant and independent predictors of long-term mortality. CPB strategy, however, was not significantly related to mortality (p=0.49). Conclusion: Surgical DTA repair was practicable in terms of acceptable perioperative mortality/morbidity as well as favorable long-term survival. Age and LV function were risk factors for long-term mortality, irrespective of the CPB strategy.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.577-582
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• 2002

Effects of the addition of single or blends of konjac flour (KF), carrageenan (CN), and soy protein isolate (SPI) into the sausage formulation were determined based on the physico-chemical and textural characteristics of low-fat comminuted sausage (LFS, fat <3%). LFSs had a pH range of 6.10 to 6.16, 77-79% moisture, <3% fat, and 13-15% protein contents, whereas regular-fat sausages (RFSs) had a pH value of 6.11, 62.5% moisture, 19.4% fat, and 11.9% protein. LFSs containing fat replacers were reduced (P<0.05) cooking loss (CL, %). KF alone or mixed with other hydrocolloids slightly improved the water-holding capacity, whereas CN increased (P<0.05) the gel strength, resulting in higher hardness values. Replacement of 6% lean meat with 1.5% SPI alone increased (P<0.05) yellowness (Hunter b value) and expressible moisture (EM, %). TPA values of KF+CN+SPI were the most similar to those of RFSs. These results indicated that triple addition of KF, CN and SPI at the ratio of 1 : 1 : 3 in LFS formulation improved functional properties, as compared to the low-fat control, and had textural characteristics most similar to those with RFSs.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.993-999
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• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• Korea journal of population studies
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• v.9 no.2
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• pp.67-78
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• 1986

With Economic Development Plan, the Korean National Family Plan Program was introduced in early 1960's. The program, which has been a way for constraining population increase, has obtained excellent results. In other word, it has had an important role in controlling the increase in population. The purpose of this study is to analyze the change of fertility rates since 1970 and the lever of completed fertility of Korean women since 1960. There are Age-specific Fertility Rate(ASFR), Total Fertility Rate(TFR), Gross Reproduction Rate(GRR) and Net Reproduction Rate(NRR) etc. in indices of period fertility. It is also possible to be seen the completed fertility rates by using Parity Progression Ratio. The data necessary for this study were obtained from Population & Housing Census Report from the year of 1960 to 1980 and Vital Statistics from 1980 to 1984, which conducted by Economic Planning Board, Republic of Korea. The summarized results of this study were as follows : 1. Age-specific Fertility Fertility Rate(ASFR) has been continuously decreasing till now. The ASFR for the women aged 25 to 29 was higher than those of any other groups and the ASFR for the women aged 20 to 24 was higher than that of the women aged 30 to 34 since the mid 1970's. 2. There are Total Fertility Rate(TFR), Gross Reproduction Rate(GRR) and Ney Reproduction Rate(NRR) etc. in reproduction rates. First of all, TFR and GRR have been declining except late of 1970's and TFR showed 2.23 per ever-married women, GRR was 1.05 in 1982. Next, the change of NRR could not be found without life table by year and only NRR for the time of census was to be found. In 1980, NRR showed 1.27 per ever-married women and the level was still out of reach at replacement level of population. 3. Specific Fertility Rate by Birth Order(SFRBO) showed to be declined continually since 1972. Especially the SFRBO of the third live birth was decreased from about 22 per 1,000 ever-married women in 1972 to 12 or so in 1982. 4. To know the level of completed fertility, the mean number of completed live births per ever-married women was calculated from 1960 to 1980. The number of completed live births was more than 5 per ever-married women by the year of 1975 but have been declining and resulted in 4.69 in 1980.