• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.362-370
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• 2001

The internal or external restraint of thermal and dry shrinkage movements could thus generate tensile stresses in concrete pavement for early traffic opening. Restrained shrinkage and thermal stresses could produce microcracks in concrete which increase its permeability and accelerate its long-term deterioration under weathering and load effects. Fiber reinforced concrete is an effective approach to the control of microcrack and crack development under tensile stresses. This study aims at evaluation of the durability of high early strength concrete for early traffic opening and increase of service life. Three different types of regulated-set cement which recently has been used much in Korea were adopted. Fibers were added and their mixtures were compared with plain high early strength concrete mixture. The use of fibers increased durability performance of high early strength concrete using regulated-set cement than the corresponding plain mixtures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.103-110
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• 2019

Damage to the pavement system due to various causes will be required rapid repair work for reopening the vehicle traffic. The magnesium oxide phosphate composite(MPC) has a short curing time and is capable of early compressive strength development, is suitable for rapid repair materials. The aim of this study was to evaluate the hardening and compressive strength characteristics of MPC according to the water-binder (W / B) ratio and magnesium-phosphate(M / P) ratio in order to develop repair materials consisted with light burned magnesia and potassium dihydrogen phosphate. In order to ensure the workability in the field application, the difference of mechanical properties according to standard sand and ordinary sand and performance of retards were evaluated. The mix proportion with W/B ratio was about 35% and the M/P ratio was about 1.0 ~ 1.2 has a superior perfomance with strength and hardening condition. Especially, the strength of composite at only 1 day curing with W/B ratio of 0.35 and the M/P ratio of 1.2 was shown the higher than 25.0 MPa. Boric acid as a retarder was found to be suitable for ensuring the working time, and the purity of magnesium oxide was about 90 ~ 95%, which is effective for ensuring curing time and strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.587-598
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• 2012

Successful implementation of infrastructure asset management system can be started with rich and reliable data. However, measurement errors in the data have always existed in the real world caused for many unknown reasons. It disturbs maintenance activities of agencies, and makes negative effects to reliability of research results on forecasting deterioration process and life cycle cost. Above all, it makes a contradiction that road agencies cannot believe their inspection data surveyed by their hands. It is particularly serious in the road pavement management field. Although road agencies are well recognized the fact, inspecting without measurement error would be a great challenge. Considering the facts, this paper aimed to suggest statistical error processing methods to correct latent error included in pavement surface inspection data. As alternatives, this paper suggested two methods based on probability distribution to consider structure of error and reliability of the data. The suggested methods were empirically tested by using pavement inspection data from Korean National Highway. As the result, this paper confirmed that conventional error processing that just removes only visible errors is not enough to cover uncertainty in pavement deterioration process. The suggested methods would be useful for improving reliability of analysis results required for road infrastructure asset management.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.117-122
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• 2011

Asphalt concrete pavement can be widely seen on urban streets, highways, parking lots, and bike trails. Asphalt concrete pavement is relatively temperature sensitive materials due to the viscoelastic behavior, which can be defined as flexible performance in summer and rigid performance in winter. In terms of maintenance, it can be fixed quite easily if damaged. In addition, asphalt concrete pavement is generally found to be black and grey in color. However, several colors can be adopted to change the appearance of plain old boring, black and grey. Generally, there are two types of color systems in hot mix asphalt concrete materials. One system uses colored cementitious material that is applied to pavement surface through coating the surface of the asphalt pavement. The major disadvantage to this system requires a careful skill set to be used on the construction site in order to prevent taking off the cementitious material. The other coloring system colors the asphalt hot mixtures through using color additives. The main advantage to this system is that the asphalt pavement layer is colored using the same techniques that are already used in paving. The disadvantage is that the colors are limited to mainly reds and browns. In this study, a suggested color additive was evaluated, based on rutting, moisture sensitivity, and fatigue cracking performance.

• Food Science of Animal Resources
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• v.25 no.4
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• pp.415-422
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• 2005

The pork loin used in this study was obtained from carcass chilled for 24 hours after slaughter and divided into 2 pare. The first part was air packaged and the other part was vacuum packaged, both of which were chilled at $4^{\circ}C$. After 2 days of slaughter, the qualities of air packaged loin chilled for 1 day showed lower drip lose, higher water holding capacity and better sensory texture than the vacuum packaged port (p<0.05). On the other hand, the air packaged loin chilled for 2 days showed lower drip loss and shear force value(SFV), higher Hunter's $a^*$ value, higher amount of taurine and alanine, and better taste, texture, juiciness and palatability than the vacuum packaged pork (p<0.05). However, the air packaged loin chilled for 3 days showed lower hip loss, chewiness SFV, higher amount of VBN $(12.37\;mg\%)$ and total plate count $(2.6\times10^4\;CFU/cm^2)$ than the vacuum packaged pork chilled for the same day (p<0.05). for the same chilling period, there was not significant difference between air and vacuum packaged pork in pH, TBA value, $L^*$ value, $b^*$ value, cooking loss, hardness, springness, cohesiveness, gumminess, total free amino acid contents and cooked meat aroma (p>0.05). Considering all these results, it is recommended that the way of air packaging for the pork with a short storing period should be reconsidered to cut down expenses.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.9-16
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• 2010

Roughness is the most important factor to maintain the road performance, and affects greatly on the design life in Jointed Plain Concrete pavements. Also, the factors the evaluate pavement‘s commonality is the three method such as functionality, safety and structural performance. In evaluating function of road, representative factors is the roughness, which has been used to determine maintenance time as key standard. As research for roughness is absence in pavement design. Applied roughness-model had a low-reliability in Korea. Therefore, it is needed to develop reliable model in road roughness. In this research, uniform specific is applied to distribute them after selecting the concrete pavements. Concrete pavement is divided by sections of 238. Total length of this sections has 281km and account for 16% of total road length in korean concrete pavements for selected sections. Considering the korean roughness-model, the evaluation of roughness is performed for the freezing index, average annual rainfall, condition for the base, the amount of traffic as well as spalling(%), cracking(%), age(year) at the selected section at the selected section. Also, additional sections is selected to evaluate various age which affects on the roughness. As a result of the analysis, it showed that spalling(%), cracking(%), age(year), and the condition of the base affected road roughness. When the correlation with the road roughness was analyzed, the reliable model for road roughness was proposed, and the ratio that can explain road roughness was R2-68.8% and P value-0 which is statistically meaningful.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.571-579
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• 2016

RS-LMC (Rapid Setting Latex Modified Concrete) has been widely used as repair material for bridge deck overlay or rehabilitation, because the overlaid pavement could be opened to the traffic after 3 hours of curing. Although the field performance of RS-LMC generally indicates that it has an excellent bonding to the substrate and shows a long term performance, the crack by vibration of vehicles have been happened on the overlay of bridges in technical reports. In this study, experimental research was carried out to evaluate the vibration properties of RS-LMC overlays by using P.S.T (Pavement Shaking Table). Total 12 specimens were tested and the variables are Latex-cement ratio (L/C) and amplitude of vibration. The result shows that the number of cracks and the total length of cracks are reduced as the increase of Latex-cement ratio (L/C) until 15%. And the crack occurs at a very small strain than the proposed values by Walter, D, G and design codes.

• Food Industry
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• s.180
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• pp.10-26
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• 2004

제과$\cdot$제빵분야는 대표적인 내수업종이고 보수적 업종성격이 강하다고 볼 수 있다. 연간 성장률이 $30\~40\%$대의 고성장을 구가하던 과거의 좋은 시기도 있었다. 현재 우리가 처한 $\$1$만 소득에서 $\$2$만 소득으로 가는 길목에서 이 분야는 기호식품으로 완전히 변해 있다고 볼 수 있다. 저성장 내지 마이너스 성장도 올 수 있는 시대에 이미 진입했다고 볼 수 있다. 소비자의 기호를 적극적으로 반영치 못한 제품은 시장에서 생존이 어려운 시대를 이미 맞고 있고, 이러한 현상은 차후 더 심하고 세차게 진행되어 질 것이다. 엄밀히 말해 기존의 제품운영계획 그대로 진행하면 그런 기업은 퇴보하게 되어있다고 생각된다. 또 다른 말로 표현하면 이제는 제과$\cdot$제빵 산업은 과감한 변신이 없다면 이미 사양산업화 되어지고 있다고도 볼 수 있다. 과감한 변신은 무엇일까? 소비자 욕구를 정확히 파악하고 이에 부응한 제품운영계획을 충실하게 세워 시행하는 것이다. 세부적으로는, (1) 제품내용물에 좋은 기능성을 도입시키는 것이다. 소위 건강에 좋다는 각종 원료성분들을 사용한 제품을 개발하여서 생산, 판매하는 전략이다. (2) 제품의 포장의 질을 좋게 하고 고급화 시킬 필요가 있다고 본다. BT를 응용한 첨단 포장기술 도입실행이 필요하다. 소비자에게 좋은 이미지를 줄 수 있고, 포장본래의 기능 제품보호가 완벽해야 하고 사용하기에 편리하여야 한다는 것이다. (3) 외국 제품들과의 경쟁은 필수적이다. 가공식품 분야는 이제 거의 $100\%$ 시장이 개방된 상태를 맞고 있다. 외국의 고기능성 내지 고급화제품들과의 경쟁은 피할수 없는 현실을 맞고 있다. 외국시장의 정보를 면밀히 분석하고 이에 대한 대응전략은 물론 더 나아가서 외국제품을 능가 할 경쟁력있는 제품개발이 필요하다고 판단된다. R&D 분야에 투자를 필연적으로 늘여야만 한다. 국내 식품사들의 Ramp;D 투자금액이 구미선진국이 1/10이하 수준에 머물고 있는 것이 오늘날 우리들의 실정이기 때문이다. 일본 등과 FTA 협정쳬결 논의가 국가적과제로 추진되고 있는 현재의 상황에서 이에 대한 우리업계의 대응전략을 지금부터 착수하여야 할 때라고 판단된다. 기본부터 철저히 우리의 장점을 살린 실질적 대응책 마련에 많은 지혜를 발휘할 때 우리 식품산업이 대내외적으로 경쟁력을 가질수 있다고 예상된다. 이러한 상황을 미루어 볼때에 고부가가치 제품을 창출 할 수 있는 여러가지 방안을 기업과 학계 그리고 정부가 종합적으로 강구하여야 할 때인 것이다. 필자는 이에 관한 몇 가지 방안들을 제안하였다.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.45-52
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• 2013

We developed a Impulse Response Measurement System, including hardware system and data analysis software, for non-destructive test of slab structure. And, we carried out impulse response measurements on the pavement to test performance of the system. In the field test, the developed system measured impulse response stably and showed parameters immediately. Test results showed that dynamic stiffness and average mobility varies significantly depending on the characteristics of the pavement materials. Some data showed anomalous values those reflect variations in pavement itself or subsurface ground. Developed system gives informations of conditions of slab structure easily and quickly. So, 2-D monitoring with the system will be helpful in maintaining various slab structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.399-405
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• 2008

Development of the paved track is required as a low-maintenance of conventional line. The paved tracks are one of the types of the ballast reinforced tracks those are manufactured by adopting the prepacked concrete technique. The main elements of this tracks are large sleeper, low elastic pad, fastener, cement mortar, geotextile and recycled ballast. Low elastic pad is the most effective element of such tracks on the basis of stress-displacement characteristics, dynamic response and fatigue characteristics. The stiffness of the pad determine the stiffness of the track. Consequently, it is more important in case of concrete track structure such as paved track because application of low elastic pad seriously effect the durability and stability of the track. The main objective of this study is to confirm the reduction of train load, which transfer to roadbed through various pad effects. To achieve this task static, numerical analysis and real scale repeated loading test was performed while load reduction effect of low elastic pad was analyzed by using displacement, stress and strain ratio characteristics of the paved track.