• Journal of the Korean Geosynthetics Society
• /
• v.13 no.1
• /
• pp.53-61
• /
• 2014

Sea gives us a lot of benefits and one of them is a role of transporting goods easily by ship. Accordingly the industrial area or the container yard is constructed either on the low sea or near the sea. Sea dredging ground is made by pumping them using dredge pump to the inside of embankment after dredging undersea soils. The dredging ground after pumping is in the slurry state but as time goes, consolidation by the own weight happens and evaporation happens at the surface of dredging ground. The evaporation causes the crest layer in the upper side of dredging ground. Under the crest layer there is still a soil of slurry state which has just little bearing resistance. This kind of characteristics makes it difficult to get a exact bearing capacity using the equations proposed until now. In this study we have performed simultaneously both the field loading tests and the cone penetration tests on the sea dredging ground. From the result of field tests, new experimental equation for the ultimate bearing capacity has been proposed. If we use the new equation, it is believed that some design of sea dredging ground could be more accurate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.869-872
• /
• 2011

Ignition tests of an oxidizer rich preburner for a staged combustion cycle liquid rocket engine were performed to evaluate combustion performance. Design operation conditions of the tested oxidizer rich preburner are about 60 of OF ratio and 20 MPa of combustion pressure. The entire kerosene and some LOx injected into the mixing head is burned in combustion chamber and the remaining LOx injected through center holes of combustion chamber is vaporized. Full flow ignition method with hypergolic fuel was used. Each propellant was supplied in two stages for soft ignition. Test results, low frequency oscillation was occurred in low flow rate conditions under 45% of design flow rate. Stable ignition in the course of design combustion pressure was able to induce by minimization of low flow rate ignition region to escape low frequency oscillation.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.9
• /
• pp.782-789
• /
• 2018

Multi-Function Display (MFD) of Korean Utility Helicopter (KUH) displays image information(navigation, flight, topographical and maintenance information) delivered from Mission Computer (MC) during flight operation. The abnormal display of MFD such as flickering phenomenon was identified in the system development. It was solved by improving the shielding performance of the DVI cable and changing the DVI cable installation path at the first mass production. However, it was occurred again when the aircraft was operated for one or two years after delivery. It was also identified in the evaluation process of the derivative helicopters. Therefore, a comprehensive review of the aircraft system level has been performed to solve the problem of MFD malfunction at first and then a design improvement plan was derived by improving the DVI cable. In this paper, the causes of MFD anomalies are analyzed and also the process of design improvement are summarized. The validity of the improvement has been verified through the DVI cable assembly comparison test, SIL/ground/flight test.

• Tunnel and Underground Space
• /
• v.21 no.3
• /
• pp.225-234
• /
• 2011

In this study, an in situ heater test for investigating the thermo-mechanical behavior related to heat flow was carried out. It was the first in situ heater test in Korea. For the test, an adequate design of heater, observation sensors, and data logging system was developed and installed with a consideration of the site condition and the test purposes. It was possible to observe that steep joints are overwhelmingly developed in the test area from a joint survey. The major rock and rock mass properties at the test site could be determined from the thermal and mechanical laboratory tests using the rock cores from the site. From the measured rock temperature distribution, it was possible to observe the influence of the rock joints and the heat flow through tunnel wall. When the heater temperature was maintained as $90^{\circ}C$, the rock temperature at 0.3 m from the heater hole was increased up to $40^{\circ}C$.

• Journal of KIISE:Software and Applications
• /
• v.35 no.5
• /
• pp.288-296
• /
• 2008

Software in defense domain requires high quality since defense specific characteristics. To assure high quality products, development and testing activities based on well defined process must be performed. If those activities cannot support software acquisition process, the quality of acquired software product is low and combat power decreases. In this paper, we propose MND-TMM(Ministry of National Defense-Testing Maturity Model), which can help enhance software quality through testing process improvements. This paper also introduces the contents of MND-TMM architecture. MND-TMM is constituted to reflect the characteristics of defense software, development process, and testing process so as to solve the problems associated with software testing. MND-TMM is comprised of 5 maturity levels and 4 categories which have number of related TPA(Testing Process Area)s. It is expected that MND-TMM can help assess testing maturity of defense software organizations and provides guidelines to improve software testing process.

• International Journal of Highway Engineering
• /
• v.2 no.2
• /
• pp.129-138
• /
• 2000

This study presents the mechanical characteristics, such as the permanent deformation and the crack, of the large stone asphalt mixtures. The large stone mixture was studied by Kandhal at NCAT(National Center for Asphalt Technology) in 1989. Japan and Arabian countries adopted the large stone mixture for the pavement construction. The experience and the study results showed that the interlocking of the aggregate system of the large stone mixtures is stable and less dependent on the binder characteristics in high temperature. These properties are known as the rutting resistant parameters. However, the mechanical test results should be supported to prove the benefits of the large stone mixtures. The creep test, resilient modulus tests on three different temperature, wheel tracking test and ravelling tests were conducted to evaluate the performance of the large stone mixtures in this study. The test results were compared with the conventional mixtures and modified asphalt concrete mixtures. The large stone mixtures showed better rutting resistance performance.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.274-274
• /
• 2010

한국은 국제핵융합실험로 (ITER) 사업에 참여하고 있으며, 삼중수소 증식을 시험하기 위한 시험 모듈(TBM, Test Blanket Module)로서 HCML (Helium Cooled Molten Lithium) TBM을 설계, 개발하고 있다. 헬륨 및 액체 리튬을 냉각재와 증식재로 사용하는 개념으로, 구조재로서 Ferritic Martensitic (FM) 강이 사용될 예정이다. 특히, HCML TBM의 일차벽은 중성자 및 플라즈마로부터 입사되는 입자들을 차폐하기 위한 Be 차폐체와 FM강으로 구성되어 있으며, 일차벽 제작법 개발을 위해서는 Be과 FM강 간의 접합과 FM강 간의 접합 방법이 개발되어야 한다. FM강 간의 접합은 기존의 연구를 통해 접합 조건이 이미 도출되었고, 고열부하 시험을 통해 검증 완료한 상태이다. 그러나, Be과 FM강 간의 접합은 현재 개발단계에 있다. 본 논문에서는 고려 중인 구조재와 Be 차폐체 사이의 접합법 개발을 위해, 고온등방가압(HIP, Hot Isostatic Pressing) 조건을 도출하고, 운전조건과 유사 혹은 가혹한 조건에서 고열부하를 인가하여, 그 건전성을 평가하는 일련의 과정을 기술하였다. 본 연구에서는 Be과 FM강 간의 접합법 개발 및 검증을 위해 제작된 $80{\times}80{\times}1$ Be/FM강 mock-up을 국내에서 구축된 고열부하 시험 장비인 KoHLT를 활용하여 수행한 고열부하 시험에 대한 것이다. 본 mock-up은 $80{\times}80{\times}10mm(t)$의 Be tile 3개를 동일 크기에 두께가 각각 25mm와 50 mm인 FM강과 스테인레스강에 접합된 것으로, 고열부하 장비에 설치하여 고열부하 시험을 수행하였다. 냉각수의 온도 및 속도는 25 C, 0.15 kg/sec로 유지되었고, 열부하는 $0.5\;MW/m^2$로 유지하였다. 시험 조건에 대한 예비해석을 통해, 가열시의 온도 및 stress, strain 분포를 얻었고, 이를 통해, cycle to failure 값을 도출하였다. 1000 사이클의 가열 실험을 마친후 초음파를 활용한 접합 계면의 결함확인 및 파괴검사를 통한 접합 건전성을 확인하였다. 3가지 접합법 모두 일부 접합면이 이탈되었으며, 향후 보다 건전한 접합방법 개발이 진행되어야 할 것으로 보인다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.403-406
• /
• 2007

발전소 온배수의 원활한 배수를 위한 설계 낙차와 함께 남서해안의 조위변화에 따른 낙차의 이용가능성을 인지하고 소수력 발전 방식과 조력발전 방식의 특정을 동시에 활용하는 해양소수력 발전소를 삼천포 화력발전소 배수로에 최초로 건설하여 운전함으로써 청정 재생에너지 개발 및 $CO_2$ 저감효과 창출에 이바지하고 있다. 본 연구에서는 삼천포 해양소수력 발전소의 운전실적 자료를 토대로 조위 및 방류량의 변화에 따른 해양소수력의 효율 특성을 분석하고자 한다. 해양소수력 발전소의 효율은 방류량과 유효 낙차의 영향을 직접적으로 받기 때문에 관측한 수위 및 방류량, 해양소수력발전소 운전실적 자료를 토대로 효율분석을 실시하였다. 우선, 소수력 가동 이후 배수로에서의 수위 상승이 명확히 나타났으며, 배수로내 위어에서의 흐름구조가 완전월류 상태에서 불완전월류로 바뀌면서 배수로 전체의 수면 불안정성이 크게 증가하였으나, 배수로의 범람이나 순환수 계통에의 큰 영향을 초래할 만한 수준은 아니었다. 성능시험 결과, 최대출력, 평균출력, 최소출력 모든 부분에서 설계 보증치 이내의 값을 보였으며, 효율 또한 설계 보중치를 상회하는 결과를 보였다. CWP 유량 분석결과, 소수력 발전소에서의 유량이 과소 측정되고 있음을 확인하였으며, 최대낙차에서 최대효율을 보이고, 저낙차일 때는 보증치보다 효율이 낮게 나타나는 결과를 보였다. 또한 조위조건을 고려한 유량을 이용하여 산정한 효율 곡선이 보증치와 가장 일치하였으며, 전체 시스템 효율은 비교적 양호한 상태임을 알 수 있었다.

• Aerospace Engineering and Technology
• /
• v.5 no.2
• /
• pp.67-76
• /
• 2006

This paper describes the analysis method to define the system specification for conducted EMI environment and verification method to evaluate the conducted EMI performance. Conducted EMI environment is characterized by the electrical power subsystem which is mainly issued by the switching circuit noise, common ground impedance coupling. To define and control these EMI problems, EMI assesment through system analysis are preceded at the early design phase and then EMI reduction methods are applied during the unit/system development phase. System EMC should be carefully controlled and designed in the consideration of EMC safety margin and its performance is fully evaluated at the whole development period.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.2
• /
• pp.497-505
• /
• 2017

TDF (Tire derived fuel) Fly ash is an industrial by-product when scraped tire was used a fuel source at the power plant. TDF Fly ash has been classified as domestic waste at the workplace so far and has not been appropriately utilized. We conducted a fundamental physical property test of asphalt mixture to investigate the possibility of using TDF Fly ash as a mineral filler of asphalt mixture for exploring new usage strategies. TDF Fly ash meets KS F 3501 asphalt mixture mineral filler criteria. And the optimal asphalt binder amount was determined to be 4.5% by Marshall design. Mineral filler content was determined at 3% and analyzed by comparing using mineral filler as stone powder. The basic physical property test of the asphalt mixture was evaluated to the provision indicated in "Production and Construction Guidelines for Asphalt Mixture" published by the Ministry of Land, Infrastructure and Transport. In the test, Marshall stability test, dynamic immersion test, tensile strength ratio test, wheel tracking test were carried out. As a result of the experiment, Marshall stability and dynamic stability satisfied the standards, and confirmed the stability and Dynamic immersion and tensile strength ratio test that TDF Fly ash is more effective for scaling and moisture resistance than stone dust. Therefore, in this research, it is expected that multilateral utilization of TDF Fly ash, and a positive effect can be also expected.