• Journal of the Korean GEO-environmental Society
• /
• v.13 no.2
• /
• pp.67-73
• /
• 2012

Asphalt pavement waste can be recycled by crushing and heating methods with additional virgin materials and additives. In this study, a new additive using Sasol wax and Polyolefin elastomer was used for improving the quality of the Superior recycled asphalt pavement(SRP). Additive was added into the recycled mixture by 1.5% and 3% of binder content in order to have PG 70-22 and PG 76-22. Both mixtures were tested by Marshall apparatus, indirect strength testing methods, toughness testing methods, moisture susceptibility testing methods and wheel tracking testing methods. Test results met the standards of KS F 2349 and GR F 4005. Through research, it was found that these special recycled mixtures could be applied for the surface and base course of heavy traffic roads or equivalents. About 13,000 tons of the recycled mixture has been applied on Seoul Olympic road to provide new road to Hangang park for Seoul citizens.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.133-133
• /
• 2012

기후변화에 관한 정부 간 패널 IPCC의 4차 보고서에 의하면 지난 100년간 지구 평균 기온의 선형추세선 기울기가 $0.74^{\circ}C$/년을 보이고 있으며 21세기말 지구의 평균기온은 최대 $6.3^{\circ}C$까지 더 상승할 것으로 전망하고 있다. 이러한 대기기온의 상승은 저수지 및 하천의 수온과 밀접한 관계를 지니는데, 저수지 표층 수온 및 유입 하천의 수온을 증가시켜 저수지 수온 성층형성시기를 앞당겨 성층화 기간을 증가시키고 또한 성층강도도 증가하게 된다. 이러한 수온성층기간 및 강도의 증가는 심수층의 용존산소 고갈과 이에 따른 퇴적층의 영양염류 용출량을 증가시켜 저수지 수질관리에 어려움을 야기할 것으로 전망되고 있다. 특히 온대기후대에 속하는 우리나라의 대부분의 대형 인공 저수지는 여름철 뚜렷한 수온성층구조가 확인되고 있어 대기기온 상승이 수온성층구조에 미치는 영향을 분석하는 것은 미래 기후변화에 대비한 저수지 수질관리 전략 수립을 위해 필요한 기초 연구라 판단되어진다. 본 연구에서는 2차원 횡방향 평균 수치모형(CE-QUAL-W2)을 활용하여 대기 온도 변화에 따른 충주호의 수온분포를 모의하고 수온 성층구조의 변동경향을 분석하였다. 지구 온난화 영향 모의에 앞서 2010년과 2008년의 충주호 수문조건에 모형을 적용하여 수온 성층구조의 재현성을 확인하였다. 미래 대기기온 자료는 국립기상연구소에서 제공하는 한반도 기후전망 모의자료(RCM) 중 충주댐 유역의 평균 기온자료를 수집하여 사용하였으며, 모의연도는 2011, 2040, 2070, 2100으로 하였다. 또한, 대기기온과 유입수온 자료를 제외한 모든 입력자료는 보정년도인 2010년과 동일하다고 가정하여 대기기온 변화의 영향만을 고려하였다. 2011년에 비해 2100년의 대기기온이 연평균 $2.44^{\circ}C$ 증가하였을 때 표층수온은 평균 $1.72^{\circ}C$, 최대 $4.31^{\circ}C$ 증가하는 것으로 나타났으며, 심층수온은 평균 $0.36^{\circ}C$, 최대 $1.33^{\circ}C$ 증가하는 것으로 나타났다. 성층구조 형성기간의 비교를 위해 표층과 심층의 수온이 $5^{\circ}C$ 이상의 차이를 보이는 기간을 조사한 결과 2011년에 비해 2100년에서 5일 일찍 시작되어 11일 더 지속되는 것으로 나타났다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.262-262
• /
• 2004

오오스테나이트 스테인리스강은 강도, 연성, 인성, 내식성 등이 우수하여 광범위하게 사용되고 있지만 절삭 시 전단저항이 크므로 절삭날 결손이나 용융을 유발하여 가공면을 안정시키기 어려우며 난삭재로서 가공경화가 매우 큰 재료이다. 그리고 질소를 약 0.1wt.％ 첨가한 316LN강은 316L강에 비해 고온강도 특성이 우수하여 주목받고 있는 새로운 재료이이지만, 저탄소의 강도 약점을 보완하기 위하여 고용강화원소로 질소를 첨가하기 때문에 높은 강도로 인하여 절삭가공에 난점이 있으므로 이 재료를 응용하기 위해서는 절삭 시 재료 표층부에 발생하는 가공 변질층에 관한 연구가 필요하다.(중략)

• Journal of the Korean earth science society
• /
• v.25 no.2
• /
• pp.87-93
• /
• 2004

To study the effect of cloud on the variabilities of turbulent fluxes over the flat terrain, we used the gradient method to analyze the dynamic and thermodynamic data from the meteorological 9-m mast (0.75, 3 and 9 m) in Villafria airport in Spain. The decrease of the surface wind speed is governed by cooling at the surface following the evening transition. The sensible heat flux and the momentum flux are increased with the dynamic factor rather than the thermodynamic factor, and the sensible heat flux was not affected by the thermal condition. The global radiation did not play an important role in the variation of the sensible heat flux in the cloudy day, but the atmospheric surface layer was characterized rather by the wind intensity.

• Journal of the Korean Geosynthetics Society
• /
• v.6 no.2
• /
• pp.9-15
• /
• 2007

Bedding zone in CRFD (Concrete Faced Rockfill Dam) requires bearing capacity to support the concrete face slab uniformly. Also, shear strength which is a key factor in slope stability and impermeability which is to prevent a loss of soils in case of leakage of concrete slab face are needed. In this study, trial prototype construction for bedding zone in CRFD was performed to investigate the compaction characteristics of bedding zone according to the frequency of compaction, water contents and so on. As a results of series of field test, the compaction characteristics of bedding zone in CRFD was affected considerably by the depth of compaction layer and frequency of compaction.

• Journal of the Korean Geosynthetics Society
• /
• v.20 no.1
• /
• pp.35-44
• /
• 2021

This research studies the stabilization method for improved soil sloped through the on-site application of Paper Flyash ground stabilizers. The target strength required for improved soil is 500 kPa, and the compressive strength for the slope surface needs to be less than 1,000 kPa after the improvement in order to plant vegetation. To meet this condition, we mixed soil from the site and the ground stabilization material, which is the main material for surface improvement material, performed mixing design and conducted various tests including strength test, permeability test and plantation test. After analyzing the results of the compression test on improved soil slope, we proposed soil constants for the improved soil. In order to evaluate the applicability of the improved soil on the slope, the site construction was carried out on the collapsed slope and the reinforcement evaluation of the surface of the improvement soil was conducted. The stability was not secured before the reinforcement, but the test shows after the reinforcement with improved soil, the safety rate is secured up to 48 hours during the raining period. In addition, the compressive strength of the improved soil at the site was secured at more than 200 kPa adhesion as planned, and the soil hardness test result was also found to be within the specified value of 18-23 mm, which increased the resistance to rainfall and ability to grow plant on the surface for improved soil.

• International Journal of Highway Engineering
• /
• v.6 no.2 s.20
• /
• pp.61-70
• /
• 2004

Cement treated Soil has superior characteristics as pavement-base including strength, curability, hardness, freezing resistance. However drying shrinkage of Cement treated base has been indicated as disadvantage, since reflection crack of surface layer is induced from drying shrinkage of cement treated base. This study propriety about low-shrinkage cement treated base that can control shrinkage of cement and control reflection crack at asphalt overlay & concrete slab.

• Journal of Ocean Engineering and Technology
• /
• v.18 no.4 s.59
• /
• pp.46-51
• /
• 2004

The surface layer in dredged and reclaimed marine clay is improved by mixing of shallow soils and hardening agents, which is made of cement, containing some other special admixtures. Tests in both laboratory and field settings are performed to investigate the improvement effect and strength properties of cement-stabilized soils. The test results show that the hardening agent sufficiently improves the soil properties of the surface layer, while increasing the load-carrying capacity. The strength of cement-stabilized soils depends, primarily, on water-to-cement ratio and curing temperature. That is, the higher curing temperature and the longer curing time, the higher the strength in cement-stabilized soils. The high ratio of water-ta-cement results in a lower strength.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.3 no.1
• /
• pp.1-8
• /
• 1998

The hydrographic data collected at three different times July, 1994, May, 1995 and June, 1996 around Taean peninsula in the mid-Yellow Sea off Korea, well known for the well-defined surface thermal fronts in summer, were analyzed. In the vertically well-mixed area where water depths varied from 15 m depth to 60 m depth, the temperature difference in the water column was less than $1^{\circ}C$. The temperature observed in the vertically well-mixed area was reversely related with the water depths and the coldest surface water was always observed over the deep channel with the depth of more than 50m, which developed southwestward off the promontory of Taean peninsula, irrespective of the observation period. The strengths of surface thermal front observed in June were much stronger than those in July, even though the surface temperature of stratified area were nearly the same as in July. These observed features could be explained as follows: A major physical process for the formation of the surface thermal front is the vertical mixing of water column but the detailed thermal structure in the study area depend on the physical parameters such as the water depth in the vertically well-mixed side and the vertical thermal structure in the stratified side.

• Proceedings of the KAIS Fall Conference
• /
• 2011.05a
• /
• pp.292-295
• /
• 2011

본 논문에서는 배수성(저소음)포장을 포함하는 2-Layer 아스팔트 포장의 상부층과 하부층의 역학적인 특성을 평가하는데 목적이 있다. 연구 방법으로는 슈퍼페이브 배합설계로 2-Layer 아스팔트 포장의 상 하부층 시편을 제작하였으며, 시편 상부층의 최대공칭치수는 4.75mm이고 하부층의 최대공칭치수는 13mm이다. 이 시편에 대한 기본 물성 시험 실시 후 마샬 안정도 시험에 대한 안정도와 흐름값을 평가하였다. 그리고 상부층과 하부층의 자유단 공진주 시험을 통해 탄성계수(E)를 측정하였고, 비파괴 시험법인 슈미트해머(Schmidt hammer)를 이용해 반발경도를 측정한 후 강도를 추정하였다. 또한 일축압축시험으로 측정된 압축강도로 탄성계수($E_{50}$)를 계산하였다. 마지막으로 각각의 역학적 시험을 통해 얻어진 결과값으로 강도(qu)와 탄성계수 ($E_{50}$)의 상관관계와 추정식으로 구한 강도와 일축압축강도 시험으로 얻어진 강도와의 상관관계를 분석하였고, 자유단 공진주 시험의 탄성계수(E)값과 일축압축시험의 결과로 얻어진 탄성계수($E_{50}$)의 상관관계를 분석하였다.