• Conservation Science in Museum
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• v.11
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• pp.1-8
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• 2010

Conservation re-treatment of dagger and scabbard in Gyeongju National Museum, which were excavated from Gyerim-ro Tomb No. 14 (Treasure No. 635) was carried out after a wide-scale dissembling in order for publishing a report and holding a special exhibition. The interior shape of the iron dagger which was disclosed by ornament plates was confirmed by X-ray investigation. The results of XRF analysis which was used to analyse compositions of the golden ornament plates reveal that having more than 3% of copper distinguishes it from other Silla gold artifacts. The conservation treatment progressed in a way that surface contaminants were removed and insecure areas were consolidated. The original shape of the iron dagger and scabbard was found after adhering and restoration. With the ornament plates staying on the iron dagger, a stand in acrylic for display and storage was made, which is able to place the dagger and scabbard in the safest way.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3532-3536
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• 2012

Understanding of the maternal transcriptome increased to elucidate the underlying molecular mechanism of normal oocyte maturation, which depends on a precise sequence of changes in maternal genes expression. Previous reports that the translational potential of a maternal mRNA is generally determined by the length of the poly(A) tail, and deadenylation is usually the first sign of mRNA degradation. However, in vitro cultured system has the underlying molecular mechanisms remain unclear. We determined whether the role of molecular basis, four important maternal genes, C-mos, cyclin-B1 (regulatory subunit of MPF), BMP15 and GDF9, were selected for detection of their precise mRNA expression patterns by real-time PCR and for determination of their polyadenylation status by poly(A) tail PCR during oocyte maturation. In the present study. the abnormal expression of maternal mRNAs prior to zygotic genome activation, which results in suppression of the corresponding protein level, may be responsible for, at least in part, a profound defect in further embryonic development. Reasonable expression of maternal gene is crucial for proper oocyte maturation and further embryonic development.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.413-413
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• 2018

최근 도시지역에 태풍과 집중호우로 인한 홍수발생 빈도와 그 규모가 커지고 있다. 이에 따른 재산 및 인명피해 양상도 매우 심각한 상황이다. 태풍 차바 처럼 강력한 10월 태풍의 출현은 지구 온난화의 전조로 받아들여지고 있다. 또한 10월 태풍임에도 초속 56.5m의 순간 최대풍속과 시간당 최대 116.7mm(제주 서귀포), 139mm(매곡) 등의 강수량은 지역 최대 강수량을 기록함으로써 이제 언제나 태풍 및 홍수에 대한 대비가 필요하게 되었다. 현재 재해에 대비하기 위해 다양한 대책들은 꾸준히 마련되어지고 있으며, 설계 기준 또한 강화되었다. 그러나 저류조 및 배수펌프장 등의 시설물 설치에는 막대한 예산이 필요한데다 장기간의 시간이 필요하며, 비구조적 대책도 마련되어 있으나 태풍 차바의 사례에서 경험한 것처럼 재해 발생 시 대책과 구체적인 방안의 마련이 더욱 시급해 보인다. 이에 본 연구에서는 태풍 차바 시의 호우에 대하여 UNET모형에 의한 부정류모의를 수행하였다. 부정류모의의 경계조건으로써 상류단 경계조건과 측방유입량 조건은 HEC-HMS를 이용하여 유출해석을 실시한 다음 입력 자료로 이용하였으며, 하류단 경계조건으로는 국토부 관할 수위지점의 수위를 이용하여 UNET 모형에 의한 수리학적 하도추적을 수행하였으며, 저지대 침수분석은 지형정보시스템 응용프로그램 중 하나인 ArcGIS를 활용하여 대상유역의 벡터자료를 구축하고 인접도엽의 접합 및 보정을 실시하여 수치고도자료를 생성하여 2차원 홍수범람해석을 위한 HEC-RAS 5.0을 적용하여 침수분석을 수행하였다. 본 연구의 결과를 수재해 피해저감 대책을 수립하는데 기초자료로 활용될 수 있을거라 판단된다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.151-155
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• 2006

In these days, welding is the most commonly used metallic connection technology and also is the fundamental production technology of the modem industrial, which is used in various areas of the industrial fields, such as shipbuilding, automobiles, airplanes and plant facilities. However welding process produces strong light, electric currents, and fume gases etc., and the welding automation is not so easy compared to the other works of manufacturing industries which produce the standardized products in large quantities. So it is difficult to weld and detect the all kinds of seams automatically by a specific sensor. In this paper the sensor applying strain gauges is used to detect the seams of triangular wave form. With the auto carriage having the sensor we proposed the experiment to weld and track the seam automatically.

• Journal of IKEEE
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• v.25 no.3
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• pp.467-472
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• 2021

Stable operation of semiconductor devices is needed even at high temperatures. Among the structures of semiconductor devices, the area that can cause unstable electrical responses at high temperatures is the contact layer between the metal and the semiconductor. In this study, the effect of annealing conditions included in the process of forming a contact layer of nickel silicide(NiSix) on a p-type SiC layer on the specific contact resistance of the contact layer and the total resistance between the metal and the semiconductor was investigated. To this end, a series of electrodes for TLM (transfer length method) measurements were patterned on the 4 inch p-type SiC layer under conditions of changing annealing temperature of 1700 and 1800 ℃ and annealing time of 30 and 60 minutes. As a result, it was confirmed that the annealing conditions affect the resistance of the contact layer and the electrical stability of the device.

• Composites Research
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• v.31 no.6
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• pp.392-397
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• 2018

In this study, the development purpose is to replace steel Tie Rod of commercial vehicle to the carbon composite by a braiding process. CFRP tie rod was designed to meet the performance requirements of existing products by designing the cross section of the core for braiding weaving and the structural design of the joint between the core and the carbon fiber. The specimens were fabricated by braiding method and applied to structural analysis through test evaluation. The manufacturing process proceeded from braiding to infusion through post-curing process. The test evaluation of the final product was satisfactorily carried out by sequentially performing tensile test, torsion test, compression test and fatigue test. In addition, the weight of CFRP tie rod could be reduced by about 37% compared to existing products.

• Journal of Advanced Navigation Technology
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• v.25 no.3
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• pp.194-202
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• 2021

Ionosphere, one of the largest error sources, can pose potentially harmful threat to single-frequency GNSS (global navigation satellite system) user even after applying ionospheric corrections to their GNSS measurements. To quantitatively assess ionospheric impacts on the satellite navigation-based applications using simulation, the standard deviation of residual ionospheric errors is needed. Thus, in this paper, we determine conservative statistical quantity that covers typical residual ionospheric errors for nominal days. Extensive data-processing computes TEC (total electron content) estimates from GNSS measurements collected from the Korean reference station networks. We use Klobuchar model as a correction to calculate residual ionospheric errors from TEC (total electron content) estimate. Finally, an exponential delay model for residual ionospheric errors is presented as a function of local time and satellite elevation angle.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.13-20
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• 2021

Post-installed anchor is a structural material that connects structural and non-structural members to existing concrete members. However, there are cases where rebar interception and construction error occur at the site. In that case, measures are needed to prevent performance degradation of the rear-installation anchors. In this study, in order to evaluate the performance of torsional control expandable post-installed anchors for compressive strength and effective depth of the reference concrete was tested. The results of the most commonly used tests of M10 and M20 showed that had variable coefficients within 15%, satisfying the reliability presented in KCI(2017). It was also confirmed that the depth of the buried and the strength of concrete affect the strength of the pavement. Based on the results of the existing similar studies and the results of this study, the design equation of the post-installed anchor was proposed and the results were compared with the existing design.

• Composites Research
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• v.20 no.5
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• pp.34-42
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• 2007

Strength and failure of adhesively bonded carbon composite-to-aluminum single-lap joints were studied by experiment. The main objective of this study is to investigate the effect of various parameters such as curing pressure for bonding, overlap lengths, and adherend thickness on the failure loads and modes of the bonded Joints with dissimilar materials. Experimental results show that the bonding pressure for composite-to-aluminum dissimilar materials should be 4 atm at the lowest. Failure load of the joints increases as the overlap length increases, but the strength (failure load divided by bonded area) decreases rapidly after the overlap width-to-length ratio is greater than 1. When the adherend thickness increase to double, bonding strength increase $12{\sim}55%$. Major failure mode of the joints is the delamination in the composite laminate and the location of delamination goes deeper into the laminates as the bonding pressure and overlap length increase.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.346-346
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• 2020

홍수기 효과적인 하천관리를 위해서는 광역 모니터링을 위한 기술 확보가 매우 중요하며, 최근 드론을 활용한 하천 모니터링에 관한 관심이 점차 증가되고 있다. 하천관리에 필요한 드론 탑재용 센서는 기본적으로 RGB 광학센서를 비롯하여 근적외선(Nir) 및 열적외선 센서가 함께 운용되는 것이 효과적이다. 그러나 현재 판매되는 드론 카메라를 살펴보면 근적외선과 열적외선 센서가 별도로 분리되어 있고 광학센서에 비해 상대적으로 매우 고가로 판매되고 있는 실정이다. 따라서 하천 모니터링을 위해서는 광학(RGB), 근적외선 그리고 열적외선 센서가 통합된 저가의 탑재체 개발이 시급하고 이를 활용한 하천 모니터링 프로세스를 정립할 필요가 있다. 본 연구에서는 일반 드론에 쉽게 탑재 가능한 하천 모니터링용 탑재체를 개발하였으며, 이를 기반으로 하천 홍수 및 부유사 모니터링에 활용하였다. 광학센서는 하천의 주요 형상을 확인하는데 이용하였으며, 근적외선 센서는 홍수 및 부유사 탐지에 활용하였다. 특히 본 연구에서는 비교적 넓은 하천 구역에 대한 공간정보를 구축하기 위해 75% 이상의 중복도를 가지고 촬영하도록 세팅하였으며 영상접합 SW를 활용하여 정사영상을 생성하였다. 구축한 근적외선 정사영상으로부터 영상분석 프로그램을 활용하여 홍수 및 부유사 영역을 추출하였으며 이를 통해 홍수기 하천 모니터링 및 치수 업무 의사결정을 위한 정보를 제공할 수 있었다. 저가용 드론 센서는 상용 SW와의 연계가 어렵기 때문에 자동비행 프로그램처럼 해당 위치별 영상 촬영이 어려운 한계가 있었으며, 본 연구에서는 센서의 제원특성을 활용하여 자동비행 SW에서도 일정 이상의 중복도를 확보할 수 있는 비행고도별 촬영시간 등을 종합적으로 설계하였다. 이를 통해 해당 지역에 대한 하천 모니터링용 정사영상을 구축할 수 있었으며 기존의 고가용 드론 센서와 유사한 효과를 가져올 수 있었다.