• Journal of Korea Multimedia Society
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• v.22 no.5
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• pp.547-557
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• 2019

To extract the depth map from a single image, a number of CNN-based deep learning methods have been performed in recent research. In this study, the GAN structure of Pix2Pix is maintained. this model allows to converge well, because it has the structure of the generator and the discriminator. But the convolution in this model takes a long time to compute. So we change the convolution form in the generator to a depthwise convolution to improve the speed while preserving the result. Thus, the seven down-sizing convolutional hidden layers in the generator U-Net are changed to depthwise convolution. This type of convolution decreases the number of parameters, and also speeds up computation time. The proposed model shows similar depth map prediction results as in the case of the existing structure, and the computation time in case of a inference is decreased by 64%.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.678-680
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• 2023

본 연구는 2022년 유네스코 인류무형유산 대표목록에 등재된 탈춤 동작을 디지털화하여 후속 세대에게 정보를 제공하는 것을 목적으로 한다. 데이터 수집은 국가무형문화제로 지정된 탈춤 단체 13개, 시도무형문화재 단체 5개에 소속된 무형문화재, 전승자 39명이 관성식 모션 캡처 장비를 착용하고, 8대의 카메라를 이용하여 수집하였다. 데이터 가공은 바운딩박스를 수행하였고, 탈춤동작 추정은 YOLO v8을 사용하였고 탈춤 동작 분류는 YOLO v8에 CNN모델을 결합하여 130개의 탈춤을 분류하였다. 연구결과, mAP-50은 0.953, mAP50-95는 0.596, Accuracy 70%를 달성하였다. 향후 학습용 데이터셋 구축량이 늘어나고, 데이터 품질이 개선된다면 탈춤 분류 성능은 더욱 개선될 것이라 기대한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1066-1067
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• 2007

유비쿼터스 환경에 적합한 기술로써 RFID가 많은 관심을 받고 있다. RFID는 바코드를 대체하기 위한 무선 주파수 인식 기술로 유비쿼터스를 실현하기 위한 핵심 기술이다. 하지만 무선 기술을 사용하며 비접촉으로 인식할 수 있기 때문에 악의적인 사용자가 불법적인 목적으로 사용자가 소지한 태그의 내용을 몰래 획득하여 사용자 프라이버시 침해 문제가 발생하고 있다. 이를 해결하기 위하여 RFID 보안에 관한 연구가 활발히 진행되고 있지만 수동형 태그의 제한된 연산 능력 및 저장 능력을 고려해야 되기 때문에 경량화를 고려하지 않을 수 없다. 따라서 본 방식은 한번 사용하고 폐기하는 일회용 패스워드 OTP를 이용하여 모바일 환경의 RFID 보안을 제공하는 방식이다. OTP 방식이 향후 인증 수단으로 발전했을 경우 태그를 제외한 리더의 역할을 대체할 수 있을 것이며, S/Key 방식에 타임스탬프로 재전송공격을 막고 더 안전한 방식을 제안함으로써 모바일 환경에서 사용할 수 있다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.119-131
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• 2020

A numerical model was developed using COMSOL Multiphysics to evaluate groundwater flow that causes radionuclide migration in the unsaturated zone of a near-surface disposal facility, which is considered as a domestic low and an intermediate-level radioactive waste disposal facility. Each scenario was modeled by constructing a two-dimensional domain that included the disposal vault, backfill, disposal cover, and unsaturated aquifer. A comparison of the continuous and intermittent rainfall conditions exhibited no significant difference in any of the factors considered except the wave pattern of water saturation. The input data, such as porosity and residual water content of the unsaturated aquifer, were observed to not have a significant effect on the groundwater flow. However, the hydraulic conductivity of the unsaturated aquifer was found to have a significant effect on the groundwater flow. Therefore, it is necessary to assess the hydraulic conductivity of an unsaturated aquifer to determine the extent of groundwater infiltration into the disposal vault.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.16-16
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• 2019

기후변화 시나리오 및 계절예측 자료를 포함한 기후정보를 수자원 분야에 활용하기 위해서는 기후정보의 시 공간적인 상세화(donwscaling)을 필요로 한다. 상세화의 경우 역학적 상세화와 통계학적 상세화로 구분될 수 있으며, 통계학적 상세화를 위해서는 대상 지역의 기후특성을 대표할 수 있는 장기 관측 자료의 확보가 중요하다. 국내의 경우에는 자동기상관측장비(Automatic Weather System, AWS)와 종관기상관측장비(Automatic Synoptic Observation System, ASOS)로 부터 수집된 기상관측자료를 사용할 수 있으나 기후변화 시나리오의 통계적 상세화를 위해서는 30년 이상의 자료 기간을 포함하는 ASOS 자료가 적합하다. 하지만 개발도상국과 같이 기상관측기반이 열악한 지역에서는 잦은 결측 등으로 인하여 품질이 좋은 관측자료의 획득이 어려운 상황이다. 따라서 본 연구에서는 측이 포함된 장기 기상관측 자료로부터 대상 지역의 기후특성을 재현할 수 있도록 기본적인 QC(Quality Control)을 거쳐 결측 자료를 보완할 수 있는 기법 및 R 기반패키지를 개발하여 적용성을 평가하였다. 개발된 기법의 적용성 평가를 위해서 기상청에서 QC를 통해 제공하고 있는 60개 ASOS 지점의 관측자료 중 강수량과 기온 변수를 사용하였다. 최대 50%까지의 현실적인 결측 패턴을 임의로 생성하기 위해 실제 개발도상국 관측자료의 일단위 결측 패턴을 이용하였다. 자료의 QC는 관측일 누락/중복 및 문자형 관측값 등 기본적인 오류 검사, 기온의 경우 물리적 허용 범위에 대한 검사, 최고기온과 최저기온의 비교 및 계측기 오작동에 의한 동일한 값의 반복 등을 포함한 내적 일치성 검사를 우선적으로 수행한다. 이후 결측값에 대해서 인근 기상관측소와의 상관성 분석 결과를 기반으로 결측값을 채우고, 최종적으로는 다양한 위성자료 및 재분석 자료 중에서 일단위 기후특성의 재현성 평가를 통해 선정된 격자형 자료와의 상관성 분석 결과를 기반으로 결측값을 보정하였다. 기온의 경우는 결측률이 높더라도 월평균 기후특성에 큰 영향을 미치지 않았지만 강수의 경우에는 5% 이상의 결측이 발생하는 경우 월평균 강수량에 영향을 미쳐 지역의 강수량을 과소 추정하는 결과를 보였다. 개발된 QC 기법을 강수 자료에 적용한 결과 월평균 기후특성을 잘 복원하는 결과를 보였지만, 일단위 강우 사상의 재현에 있어서는 미흡한 결과를 보였다.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.489-499
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• 2009

It is quite difficult to predict the flexural strength of post-tensioned members with unbonded tendons (unbonded posttensioned members, UPT members) because of debonding behavior between concrete and prestressing tendons, which is different from that with bonded tendons. Despite many previous researches, our understanding on the flexural strength of UPT members is still insufficient, and thus, national codes use different methods to calculate the strength, which quite often give very different results. Therefore, this paper reviews various existing methods, and aims at proposing an improved rational strength model for UPT flexural members having better accuracy. Additionally, a database containing a large number of test data on UPT flexural members has been established and used for verification of the proposed flexural strength model. The analysis results show that the proposed method provides much better accuracy than many existing methods including the rigid-body model that utilizes the assumption of concentrated deformation and plastic hinge length, and that it also gives proper consideration on the effects of primary parameters such as reinforcement ratio, loading pattern, concrete strength, etc. Especially, the proposed method also well predicts the ultimate stress of unbonded tendons of over-reinforced members, which are often possible in construction fields, and high strength concrete members.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.26-33
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• 2014

The study investigates the effects of the type, replacement ratio and method of use of mineral admixtures on the fluidity, bleeding ratio, volumetric change and compressive strength of the grout in order to provide basic data for the development of high-quality grout for PSC bridges. In view of the results relative to the type and replacement ratio of the mineral admixtures, it appears that fly ash has practically no effect on the improvement of the fluidity nor on the reduction of bleeding and shrinkage of the grout. On the contrary, blast furnace slag and silica fume appear to have significant effect on the improvement of the fluidity or on the reduction of bleeding and shrinkage of the grout. With regard to the combined use of mineral admixtures, the combination of fly ash and blast furnace slag provides satisfactory fluidity but with significant increase of bleeding and shrinkage, whereas the combination of blast furnace slag and silica fume reduces bleeding and shrinkage but with large loss of the fluidity. On the other hand, the combination of fly ash and silica fume results in satisfactory fluidity accompanied with fair reduction of bleeding and shrinkage of the grout. In view of these results, the type, replacement ratio and method of use of the mineral admixtures are seen to influence the fluidity, bleeding and volumetric change of the grout. Accordingly, it is necessary to select the mineral admixtures considering these effects for their exploitation in the grout of PSC bridges.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.301-306
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• 2015

For the purpose of developing high performance marine concrete with improved crack resistance and durability, this analytical study aimed to estimate strength, hydration heat characteristics, and chloride attack resistance of concrete with mineral admixture. Ground granulated furnace slag and fly ash were considered for mineral admixture. The replacement of ground granulated furnace slag and fly ash considered in the analysis was in the range of 0~70% and 0~40 %, respectively. The analysis results indicated that both ground granulated furnace slag and fly ash decreased compressive strength, and the effect of adding ground granulated furnace slag on mitigation of hydration heat was limited whereas fly ash had an noticeable influence on it. It was also found that the replacement with ground granulated furnace slag enhanced the chloride attack resistance but fly ash deteriorated the resistance. From the analytical studies, It could be expected that a ternary blended cement composition with proper amount of ground granulated furnace slag and fly ash might be effective to control crack resistance as well as chloride attack resistance of marine concrete.

• Nuclear Engineering and Technology
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• v.23 no.1
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• pp.56-65
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• 1991

The LOFT LOCE L2-3 was simulated using the RELAP5/MOD2 Cycle 36.04 code to assess its capability in predicting the thermal-hydraulic phenomena in LBLOCA of a PWR. The reactor vessel was simulated with two core channels and split downcomer modeling for a base case calculation using the frozen code. The result of the base calculation showed that the code predicted the hydraulic behavior, and the blowdown thermal response at high power region of the core reasonably and that the code had deficiencies in the critical How model during subcooled-two-phase transition period, in the CHF correlation at high mass flux and in the blowdown rewet criteria. An overprediction of coolant inventory due to the deficiencies yielded the poor prediction of reflood thermal response. Improvement of the code, RELAP5 / MOD2 Cycle 36.04, based on the sensitivity study increased the accuracy of the prediction of the rewet phenomena.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.661-669
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• 2021

A mechanical stiffener has been mainly applied on a PCB to secure fatigue life of a solder joint of an electronic components in spaceborne electronics by minimizing bending displacement of the PCB. However, it causes an increase of mass and volume of the electronics. The high damping PCB implemented by multi-layered viscoelastic tapes of a previous research was effective for assuring the fatigue life of the solder joint, but it also has a limitation to decrease accommodation efficiency for the components on the PCB. In this study, we proposed high damping PCB with a multi-layered superelastic shape memory alloy stiffener for spatialminimized, light-weighted, high-integrated structure design of the electronics. To investigate the basic characteristics of the proposed PCB, a static load test, a free vibration test were performed. Then, the high damping characteristic and the design effectiveness of the PCB were validated through a random vibration test.