• Composites Research
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• v.36 no.1
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• pp.32-36
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• 2023

Recently, as global environmental issues for sustainable development, such as carbon neutrality, have emerged, disposal methods of glass fiber composites, a material of existing wind turbines, have become a problem. To solve this problem, in this study, 30kW wind turbine blades were manufactured using flax fiber-based composites, which are eco-friendly natural fiber composites that can replace existing glass fiber composites, and their suitability was evaluated. First, mechanical strength tests were conducted to verify the feasibility of using eco-friendly natural flax fiber composites as a wind turbine blade material, and as a result, better strength were confirmed compared to previous studies on the properties of flax fiber composites. In addition, the suitability was confirmed through a static strength performance evaluation test to measure the static strength of the flax fiber composite blade using the manufactured 30kW class flax fiber composite blade.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.89-103
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• 2006

This study develops the tire/pavement noise measuring trailer that can minimize the effect of various environmental noise and evaluate road noise characteristics without regard to time and spots. As literature reviews, it is examined into road noise characteristics and case studies of various CPX Trailer, and made a development plan of device. Based on these, HEART CPX Trailer is developed and conduct experiments for verification of the semi-anechoic chamber suitability, precision and field application of device. In the result of the experiment for verification of semi-anechoic chamber suitability, we can make sure that it is suitable and reliable among frequency bands. In the test of repetition measurement, we can verify excellent measurement accuracy among speeds and microphone's locations. In case of field tests using HEART CPX Trailer, it is founded that the result is similar to CPB test result carried out by Chung-Ang university in 2003. It can be concluded caused that the effect of environmental noise in and around the road including mechanical noise of a tow car was excluded. This paper confirmed and suggested that HEART CPX Trailer is suitable for evaluation of real road noise characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.100-109
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• 2006

In the regeneratively cooled combustion chambers using hydrocarbon fuels, coking occurs as the wall temperature increases which generates compounds deposition on the wall. This phenomenon reduces cooling capability of the coolant, finally it can cause damage to combustor by overheating of chamber wall. In this paper electrical heating equipment which is used for the coking experiments and the test results are introduced. The compatibilities of copper alloy with let A-1 were assessed at each condition based on the test results.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.201-208
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• 2008

An active RFID system has the advantages of a long identification distance and a good identification rate as well as overcoming the passive RFID's drawback such as the lowering of identification rate on metal materials. So, the development of an active RFID system has been gradually increasing in harbor logistics and the national defense area. On the other hand, some identification failures between products developed under the same standards have been reported, and there are difficulties in evaluating the interoperability between developed Products and standard conformance test because an accurate evaluation method and equipment has not been established at the international level. Motivated by these, this study presents a realization of the hardware and software of emulator to evaluate the standard conformance of an active RFID system, Performance of the designed system are then analyzed by means of simulations of Matlab/Simulink, and the applicability of the emulator is verified by evaluating the standard conformance of a real active RFID tag.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.167-167
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• 2018

토양수분은 토양에 포함된 평균 수분량을 나타내며 수문 순환 관점에서 매우 중요한 수문변량 중 하나이다. 본 연구에서는 대표적인 기계학습 방법인 Support Vector Machine (SVM)을 이용한 토양 함수 예측 기법을 개발하고자 하며, 예측인자로서 원격 탐측 기반의 토양함수자료, 강수량, 온도 등을 활용하고자 한다. SVM은 Kernel 함수를 이용하여 복잡한 비선형 관계를 선형 가정을 통해서 해석하는 기계학습 방법으로서 전역모델(global model)로서 다양한 수문기상분야에 적용이 이루어지고 있다. SVM의 장점은 일정 부분의 오차를 허용함으로서 모형의 일반화 측면에서 기존 인공신경망(artificial neural network, ANN)에 비해 우수한 성능을 나타내며, 특히 예측모형으로서 적용성이 매우 크다. 본 연구에서는 과거 토양 함수 자료와 강수, 온도, 위성 관측 기반 정보 등을 이용하여 모형을 적합시키고 이를 미계측 유역으로 확장하는데 연구의 목적이 있으며, 본 연구를 통해 제안된 모형은 용담댐 시험유역을 대상으로 적용되며 기존 ANN 모형 및 다중회귀분석 결과와 비교를 통해 모형의 적합성을 평가하고자한다.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.45-58
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• 2015

Even though the plate bearing test (PBT) to evaluate the load baring capacity and the field density test to evaluate the relative density are mainly used for quality control of soil compaction in Korea, use of the dynamic cone penetrometer test (DCPT) and the dynamic plate bearing test (DPBT) considering economic feasibility, rapidity, and suitability for field conditions increase to use for quality control of soil compaction. In this study, bearing capacity and relative density of subgrade with thickness of 20 cm, 30 cm, and 40 cm are estimated using PBT, DCPT, DPBT and field density test in three field compaction tests, and the relationship among various compaction evaluation methods is analyzed and discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.195-200
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• 2011

KS F 2782 (for shotcrete accelerators) standard cross-section of tunnel construction or repair is a reinforcement used in the field of shotcrete accelerators as a criterion in assessing shotcrete performance. Thus, KS F 2782 by standard accelerator will determine the nature of the product of concrete accelerators that will be used to record variations in the product roles, through determination of the quality of the experimental method to identify only the quality of the many variables that exist. This evaluation standard has so far distinguished accelerator products in indoor experiments that do not meet quality standards but were mostly for an on-site accelerator mixed with the shotcrete after being quite satisfied with the level of quality in a certain number of products. This observation is derived from the results of an indoor experiment considered to verify whether the site is suitable for indoor experiments, and whether its actual location in the city is relevant to the accelerator quality, to find a way to test if it fits. This study centers on the material conditions of the shotcrete accelerator and a variety of experimental results, and used the Gilmore needle to compare the compressive strength and KS F 2782 specification of the accelerator as a means to ensure product quality conformity analysis and for further research experiments. In conclusion, a portion of KS F 2782 standard that fixes the problems that can be resolved from the ground up as a whole is not a review for the domestic reality. As an indoor experiment to ensure uniformity in the field when applied in a sufficient correlation, complement must be in place.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.68-75
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• 2011

BACKGROUND: To assess and prevent the environmental impacts and risks by veterinary pharmaceuticals, Guidance on Estimating Soil Persistence and Degradation Kinetics from Environmental Fate Studies on Veterinary Pharmaceuticals for Environmental Risk Assessment was proposed. METHODS AND RESULTS: Proposed guidance was coined by VICH, EU guideline, OECD guideline and soil dissipation studies for the purpose of international harmonizing. Guidance was also modified from pesticide soil persistence testing guidelines of US, EU, and Korea, with practical approaches adopting in-use test guideline for Korea. CONCLUSION(S): Proposed guidance are consisted of three parts; Laboratory Soil Experiment, Field Soil Dissipation Study, and Estimation of $DT_{50}/DT_{90}$. Proposed guidance is to be available for the requirement for registration of veterinary pharmaceuticals with fit for purpose in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.545-550
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• 2016

The main purpose of this study is to analyze and evaluate the feasibility of ligthweight pavement system with pile foundation on soft soil by laboratory small chamber test. In order to verify the stability of lightweight pavement system, the 1/30 scaled downed model system was tested at lab. The soft soil condition was simulated and group piles for skin friction resistance were used. Within the limited lab test, the settlements of pavement system were 0.86 mm for Case A, 0.70 mm for Case B, and 0.50 mm for Case C. The converted maximum settlement differential settlement were 25.8 mm and 10.8 mm. These values meet the inside of specification of Bridge Design Guide in Korea. The use of lightweight pavement systems on soft soils could be an alternative construction method on soft soils to reduce the challenges of conventional design and constructions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.47.2-47.2
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• 2009

인체의 뼈와 같은 손상된 경조직을 치료 또는 대체하기위한 정형외과용 임플란트를 설계하는데 있어 뼈의 생체역학적 특성과 유사한 성질을 갖는 다공성 지지체에 대한 연구가 최근 관심을 끌고 있다. 다공성 지지체는 조직이 원활히 재생될 수 있어야 하며, 또한 주변 조직과도 생물학적인 고착이 잘 되도록 기공들이 상호 연결된 구조를 가져야 한다. 이와 같은 다공성 지지체용 소재를 제조하기 위하여 본 연구에서는 타이타늄 분말을 사용하여 3차원 적층조형공정으로 다공성 타이타늄 지지체를 제조하였다. 제조된 다공체의 물성 및 기계적 특성을 평가하기 위하여 압축시험과 변형해석을 수행하였으며, 아울러 제조된 지지체의 생체적합성 향상을 위하여 양극산화 공정 등의 표면처리를 수행하여 그에 대한 특성을 평가하였다. 분말야금 공정으로 제조된 지지체는 골조직의 성장에 적합한 약 $300\sim400{\mu}m$의 기공 크기를 갖도록 제어하였고, 기공도는 60~75%로 제어하였다. 아울러 다공성 타이타늄의 생체적합성을 부여하기 위하여 양극산화공정으로 지지체의 표면에 Ca 및 P을 포함하는 산화층을 형성시키는 표면처리를 수행하였다. 양극산화공정에 의하여 표면에 미세기공을 포함하는 산화층을 형성시킬 수 있었으나 이와 같은 표면구조는 조골세포의 부착과 영향에는 큰 영향을 미치지 않는 것으로 확인되었다.