PURPOSES : Korea Expressway Corporation has been working on an early remodeling project for the Jungbu Expressway to prepare methods for the rehabilitation of the old CRCP(Continuous Reinforced Concrete Pavement). In this study, the distress of the old CRCP was classified, and the engineering properties of the core specimens for each failure type were evaluated. Based on the test results, the concrete conditions of the existing CRCP were evaluated. This provides a basis for the pre-treatment or repair of the existing CRCP in the JungBu Expressway. METHODS : To evaluate the pavement condition of the Jungbu Expressway, existing PMS(Pavement Management System) data were analyzed, and field surveys were conducted for each pavement condition. The longitudinal rebar depth, rebar spacing, horizontal crack, and pavement thickness were examined through core sampling and non-destructive testing. In addition, the core specimens were used to evaluate the compressive strength, chloride penetration test, chloride ion penetration resistance, and freeze-thaw resistance. RESULTS : From the analysis of existing PMS data, field surveys, and laboratory tests, it was found that the old CRCP condition of the Jungbu Expressway was not good. Various types of failures occurred, and horizontal cracks at the rebar location, upward rebar locations, and rebar corrosion were confirmed. In addition, the compressive strength was considerably high, but the durability-related index was judged to be poor. CONCLUSIONS : For the remodeling project of the Jungbu Expressway, appropriate repairs should be carried out for each type of distress in the old CRCP.

This study is to evaluate the prior economic feasibility of the off-shore fisheries stock enhancement project. The main findings of this study can be summarized as follows: first, offshore fisheries stock enhancement project shall be implemented by dividing them into 1st·2nd·3rd projects for efficient promotion. The 1st·2nd·3rd projects will be conducted in a total of 50 locations (the eastern sea, the western sea, the southern sea, and the jeju sea areas), and the project period per unit will be five years, which will cost 1 trillion won. Second, according to the results of the survey on public awareness, the most consumed marine species in Korea over the past year were analyzed in the order of mackerel, hairtail, squid, yellow corvina, blue crab, and cod. The dominant response to the reason for consuming marine products in Korea was healthy well-being food and safe food. In addition, 67.9% of them have hesitated to purchase offshore fish species over the past year due to high prices, indicating that they are burdened by high prices. On the other hand, 79% of the respondents said that the government’s policy was insufficient, according to a survey on whether the government's coastal marine resource creation policy was sufficient. Third, as a result of preliminary economic analysis of offshore fisheries stock enhancement project, the benefit-cost ratio is 4.01, net present price is 1,283.7 billion won, and internal rate of return is 91.7% per year, which means that the economic analysis ensures the feasibility of the projects. The results of this study provide useful information on securing or organizing budgets for offshore fisheries stock enhancement project by securing economic feasibility as a national infrastructure project that increases fishery income and public benefits such as consumption of marine products.

PURPOSES : This study was conducted to evaluate the performance of pressure relief joints (PRJs) installed on highways for preventing blow-ups. METHODS : To evaluate the performance of a PRJ, pavement surface images were acquired by conducting a follow-up survey through on-site visual inspection and an automated pavement condition survey. The PRJ widths in the acquired pavement images were measured using image analysis software, and major distress in the PRJ was identified. The relationship between the performance period and the joint width was bi-linearized, and the causes of distress and repair methods for PRJ were suggested. RESULTS : As a result of the first survey, it became known that the width of a PRJ rapidly decreases after installation owing to an expansion of the concrete slab. The width of a PRJ continued to decrease, with 94% of the joint below 30 mm and 64% of the joint being below 10 mm, based on the fourth survey. The PRJ width of an Alkali-Aggregate Reaction (AAR) section decreased more than that of a normal section, but the difference in the average width between both sections decreased from 9.7 mm to 2.7 mm over the measured period. A bilinear estimation equation was developed based on the survey data. Through the estimation equation, it could be confirmed that joint contraction accelerated after installation owing to the effects of AAR, and that the joint widths of both sections converged to a similar level over the measurement period. As the result of the major distress analysis indicates, joint seal failure occurred in 70% of the joints, and the distress rates in terms of cracks, edge breakouts and spalling, and patching were 73%, 57%, and 28%, respectively. CONCLUSIONS : With the follow-up survey it could be confirmed that the concrete slab continued to expand despite seasonal changes, maintenance of the PRJ, and additional installation of new PRJs. The expansion of the concrete slab due to AAR is considered to be closely related to PRJ behavior. In addition, it is judged that major distress of the PRJ occurs at an early age owing to the instantaneous release of excessive compressive stress inherent in the slab during joint cutting.

규소(Si)는 지각의 구성 원소 중 두 번째로 흔히 존재하는 원소로, 3개의 안정동위원소, 28 Si (92.23%), 29 Si (4.67%), 30Si (3.10%)를 가진다. 규소 동위원소는 규소의 생지화학적 순환에 대한 지시자로 고환경 및 고기후 복원을 위해 전 세계에서 널리 연구되고 있다. 그러나 국내에서는 아직까지 생물 기원 규소에 대한 규소 동위원소 연구가 전 무한 실정이다. 본 연구에서는 대형 규조류 시료에 대한 규소 동위원소 분석을 위해 기존 보고된 알칼리 용융법을 정리하고 생물 기원 규소 분석에 가장 적합한 규소 분리법을 구축하고자 하였다. 해당 시료를 고온 알칼리 용융을 통해 완전 용해시킨 후 시료 내 규소를 AG® 50W-X8 양이온 교환수지를 이용하여 효과적으로 분리하였다. 분리된 시료에 대한 신뢰성 검증을 위하여 Si 동위원소 표준물질(NBS-28) 및 USGS 암석 표준시료(AGV-2, GSP-2, BHVO-2)에 대한 분석을 함께 실시하였으며, 분석된 시료 모두 기존 연구결과와 오차범위 내에서 일치하는 값을 나타내었다. 본 연구에서 개발한 규소 동위원소 분석법은 향후 국내의 지구과학 및 관련 연구 발전에 많은 도움을 줄 것으로 기대된다.

The 3D printing process provides a higher degree of freedom when designing ceramic parts than the conventional press forming process. However, the generation and growth of the microcracks induced during heat treatment is thought to be due to the occurrence of local tensile stress caused by the thermal decomposition of the binder inside the green body. In this study, an alumina columnar specimen, which is a representative ceramic material, is fabricated using the digital light process (DLP) 3D printing method. DTG analysis is performed to investigate the cause of the occurrence of microcracks by analyzing the debinding process in which microcracks are mainly generated. HDDA of epoxy acrylates, which is the main binder, rapidly debinded in the range of 200 to 500oC, and microcracks are observed because of real-time microscopic image observation. For mitigating the rapid debinding process of HDDA, other types of acrylates PETA, PUA, and MMA are added, and the effect of these additives on the debinding rate is investigated. By analyzing the DTG in the 25 to 300oC region, it is confirmed that the PETA monomer and the PUA monomer can suppress the rapid decomposition rate of HDDA in this temperature range.

In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2–3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

1. 본 연구는 GM콩이 비의도적으로 자연에 방출되었을 시 야생콩과의 교잡에 의해 발생 가능한 교잡콩을 모니터링하고 영양학적 측면에서 안전성을 평가하기 위하여 수행하였다. 이를 위해, 베타카로틴 강화 GM콩과 야생콩, 두 품종간 인위적으로 생산한 교잡콩, GM콩의 모본이자 일반 재배 품종인 광안콩 등 4품종을 국내 2개 지역에서 재배하고 콩 종자를 대상으로 주요 영양성분 38종을 분석하였다. 2. 재배 환경에 영향을 받지 않고, GM콩 및 야생콩과 비교해 교잡콩에서 유의적 차이를 보이는 성분은 조단백질, 조섬유, alanine, glycine, leucine, serine, tryptophan, oleic acid, linolenic acid, arachidonic acid 등 10종이었다. 하지만, 분석한 모든 시료의 성분은 국내외 자연 범위에 포함되는 수준이었다. 3. PCA분석 결과, 주요 영양성분 함량 변이는 GM콩은 모본과 유사하였고, 교잡콩은 GM콩 보다는 야생콩과 유사하였다. 즉, 분석한 4품종의 영양성분의 변이는 재배 환경보다는 유전적 요인에 의해 더 크게 영향을 받음을 알았다. 4. 본 연구의 결과는 GM콩과 야생콩간 교잡콩의 영양학적 안전성을 분석한 최초의 보고이며, 이는 향후 GM콩의 비의도적 자연 방출을 모니터링하는데 있어 유용한 기초 자료로써 활용 가치가 있을 것이다.

This research is conducted focusing on the 7-Dories type wooden buildings showing different rafter installation. This research found the reason why the rafter configuration look different each other and the relationship the between rafters and the Dory. Factors were compared to determine why the rafter configuration show the formal differentiation. The comparison factors are as follows: 1. The type of rafter installation is related to the longitudinal length of the building. 2. The type of rafter installation is related to the number of Kans on the side of the building and is proportionate. 3. The type of rafter configuration is related to the Dory arrangement and is proportionate. 4. The type of rafter configuration is related to the Dory’s vertical arrangement. If the Dory arrangement is small, it is identified as two-stage rafter configuration. And if the Dory arrangement is large, it is identified as three-stage rafter configuration. Eventually, it was confirmed that the rafter configuration were affected by the Dory arrangement.