• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.545-554
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• 2017

Among various applications of the High Altitude Long Endurance (HALE) Unmanned Aerial Vehicle (UAV), this paper has a focus on the Global Positioning System (GPS) utilizing pseudolite and its improved performance, particularly during the multi-purpose missions. In a multi-purpose mission, the HALE UAV follows a specified flight trajectory for both navigation applications and missions. Some of the representative HALE missions are remote exploration, surveillance, reconnaissance, and communication relay. During these operations, the HALE UAV can also be an additional positioning signal source as it broadcast signals using pseudolite. The pseudolite signal can improve the availability, accuracy, and reliability of the GPS particularly in areas with poor signal reception, such as shadowed regions between tall buildings. The improvement in performance of navigation is validated through simulations of multi-purpose missions of the solar-powered HALE UAV in an urban canyon. The simulation includes UAV trajectory generation at stratosphere and uses actual geographical building data. The results indicate that the pseudolite-equipped HALE UAV has the potential to enhance the performance of the satellite navigation system in navigationally degraded regions even during multi-purpose operations.

• Journal of Forest and Environmental Science
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• 제27권3호
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• pp.151-156
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• 2011

Seeds of Xanthoceras sorbifolia Bunge were collected from two plantations and two superior trees in Inner Mongolia: and one plantation and one superior tree in Liaoning, China in late August, 2011. Yellowhorn or goldenhorn is an important tree species, from the aspects of source of edible oil and biodiesel and pioneering capacity of degraded and desert land. Characteristics investigated were seed length, width, and weight: weight and volume of 1,000 seeds: and weight and volume of one-liter seeds. The seeds of Qingsonglingxiang No. 1, growing alone in an open space, showed the highest values in seed length (16.08 mm), width (14.48 mm) and weight (1.40 g), while those of Tree No. 160 in Ar Khorqin Banner were the lowest ones: that is, 11.48mm for length, 11.81 mm for width, and 0.73 g for weight, respectively. Traits of seeds varied quite much between trees and among areas; for example, Tree No. 38 and No. 160 produced quite different seeds in several traits, although they are adjacent to each other in the same farm. Weight of 1,000 seeds varied from 718.0 g to 1,010.1 g and volume from 0.76 L to 1.52 L. Weight of one-liter seeds were 522.3 g to 688.2 g, while the number of seeds were 603 to 935. Seeds which were soaked in the water at $4^{\circ}C$ for 2 days showed the highest germination rate (89%) in a 30-day test, which was about 10% to 40% higher than those of non-treatment and dipping treatment at $36^{\circ}C$ followed by keeping under room temperature for 2 days. 81% of seeds in the wet sand at room temperature germinated, while 23% of seeds deprived of seed coat germinated. It is necessary to understand seed traits to select superior clones or provenances for the increased, unfluctuating production of seed.

• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1218-1230
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• 2021

Cold-adapted plant growth-promoting bacteria (PGPB) with multiple functions are an important resource for microbial fertilizers with low-temperature application. In this study, culturable cold-adapted PGPB strains with nitrogen fixation and phosphorus solubilization abilities were isolated. They were screened from root and rhizosphere of four dominant grass species in nondegraded alpine grasslands of the Qilian Mountains, China. Their other growth-promoting characteristics, including secretion of indole-3-acetic acid (IAA), production of siderophores and ACC deaminase, and antifungal activity, were further studied by qualitative and quantitative methods. In addition, whether the PGPB strains could still exert plant growth-promoting activity at 4℃ was verified. The results showed that 67 isolates could maintain one or more growth-promoting traits at 4℃, and these isolates were defined as cold-adapted PGPB. They were divided into 8 genera by 16S rRNA gene sequencing and phylogenetic analysis, of which Pseudomonas (64.2%) and Serratia (13.4%) were the common dominant genera, and a few specific genera varied among the plant species. A test-tube culture showed that inoculation of Elymus nutans seedlings with cold-adapted PGPB possessing different functional characteristics had a significant growth-promoting effect under controlled low-temperature conditions, including the development of the roots and aboveground parts. Pearson correlation analysis revealed that different growth-promoting characteristics made different contributions to the development of the roots and aboveground parts. These cold-adapted PGPB can be used as excellent strain resources suitable for the near-natural restoration of degraded alpine grasslands or agriculture stock production in cold areas.

• Wind and Structures
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• 제35권6호
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• pp.405-418
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• 2022

The aerodynamic behaviour of a CRH high-speed train under three infrastructure scenarios (flat ground, embankment, and viaduct) in the presence of a crosswind was simulated using a 1/8th scaled train model with three cars and the IDDES framework. The time-averaged and instantaneous flow field around the model were examined. The employed numerical algorithm was verified through a wind tunnel test, and the grid and timestep resolution analyses were conducted to ensure the reliability of the data. It was noted that the flow around the rail line was different under different infrastructure scenarios, especially in the case of the embankment, which degraded the aerodynamic performance of the train under the crosswind. The flow around the train on the flat ground and viaduct was different, although the aerodynamic performance of the train was similar in both cases. Moreover, the viaduct accidents were noted to have the most critical consequences, thereby requiring the most attention. The aerodynamic performance of the train on the windward track of the embankment under the crosswind was worse than that of the train on the leeward track. But for the other two infrastructure scenarios, the aerodynamic performance of the train on the windward track is relatively dangerous, which is mainly caused by the head car. These observations suggest that the aerodynamic behaviour of the train on an embankment under a crosswind must be carefully considered and that certain wind protection measures must be adopted around rail lines in windy areas.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.919-926
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• 2023

To analyze the cause of the destruction of thin, carbon-backed lithium fluoride targets during a measurement of the fusion of ⁷Li and ¹⁷O, we estimate theoretically the lifetimes of carbon and LiF films due to sputtering, thermal evaporation, and lattice damage and compare them with the lifetime observed in the experiment. Sputtering yields and thermal evaporation rates in carbon and LiF films are too low to play significant roles in the destruction of the targets. We estimate the lifetime of the target due to lattice damage of the carbon backing and the LiF film using a previously reported model. In the experiment, elastically scattered target and beam ions were detected by surface silicon barrier (SSB) detectors so that the product of the beam flux and the target density could be monitored during the experiment. The areas of the targets exposed to different beam intensities and fluences were degraded and then perforated, forming holes with a diameter around the beam spot size. Overall, the target thickness tends to decrease linearly as a function of the beam fluence. However, the thickness also exhibits an increasing interval after SSB counts per beam ion decreases linearly, extending the target lifetime. The lifetime of thin LiF film as determined by lattice damage is calculated for the first time using a lattice damage model, and the calculated lifetime agrees well with the observed target lifetime during the experiment. In experiments using a thin LiF target to induce nuclear reactions, this study suggests methods to predict the lifetime of the LiF film and arrange the experimental plan for maximum efficiency.

• 터널과지하공간
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• 제34권4호
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• pp.413-420
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• 2024

도심지 터널에 적용성이 우수한 Gripper TBM 계획시 굴착공법 특성을 반영하지 않고 기존 NATM 터널의 지반이완 개념의 보강계획을 준용하여 굴착안정성 및 시공성이 저하되는 문제를 발생시키고 있다. 본 연구에서는 도심지 근접시공에 따른 보강계획시 Gripper TBM 굴착공법 특성을 고려한 지보계획의 합리화 방안을 제안하고자 하였다. 이를 위해 굴착공법별 시공조건을 고려한 3차원 안정성 검토를 수행하여 굴착에 따른 주변지반에 미치는 영향을 분석하였다. NATM공법은 굴착과 동시에 무지보 자립시간이 발생되어 굴진면에 지반이완이 집중되었으나, Gripper TBM은 커터헤드와 스킨플레이트를 통해 굴진면 주변지반을 지지하므로 스킨플레이트 후방에 지반이완이 발생되었다. 이러한 굴착공법 특성을 고려하여 연구대상현장의 근접시공에 따른 보강계획의 문제점을 지적하고 Gripper TBM 굴진안정성 및 시공성 등을 고려한 합리적인 지보패턴 개선방안을 제안하였다.

• Journal of Preventive Medicine and Public Health
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• 제36권4호
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• pp.373-376
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• 2003

Objectives : Peripheral blood-buffy coat fractions (N=14,956) have been stored at $-70^{\circ}C$ in the headquarter of the Korean Multicenter Cancer Cohort (KMCC), since 1993. To study the future molecular etiology of cancers using specimens of the cohort, properly stored specimens are necessary, Therefore, the DNA-viability of the bully coat samples was investigated. Methods : Buffy coat fraction samples were randomly selected from various collection areas and years (N=100). The DNA viability was evaluate from the UV-absorbent ratios at 260/280nm and the PCH for $\beta$-globin was performed with genomic DNA isolated from the buffy coat. Results : PCR products were obtained from 85 and 98% of the C and H area-samples, respectively, using 50 or $100{\mu}l$ of the buffy coat. There were significant differences in the yields of the PCR-amplifications from the C and H areas (p<0.05), which was due to differences in the homogenization of the buffy coat fractions available as aliquots. The PCR-products were obtained from all of the samples (N=7) stored at the C area-local confer, but the other aliquots stored at the headquarter were not PCR-amplified, Therefore, the PCR products in almost all the samples, even including the DNA-degraded samples, were obtained. In addition, an improvement in the DNA isolation, i,e. approx. 1.6 fold, was found after using extra RBC lysis buffer. Conclusions : PCR products for $\beta$-globin were obtained from nearly all of the samples. The regional differences in the PCR amplifications were thought to have originated from the different sample-preparation and homogenization performance. Therefore, the long term-stored buffy coat species at the KMCC can be used for future molecular studies.

• KSBB Journal
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• 제18권3호
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• pp.174-179
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• 2003

폐광지역으로부터 quinoline (2,3-benzopyridine)을 유일한 탄소원, 질소원, 그리고 에너지원으로 이용하는 세균 NFQ-1을 농화 배양기법을 통하여 분리하였다. 분리된 세균은 그람음성의 간균으로서 BIOLOG 시험을 통하여 Pseudomonas nitroreducens로 동정되었으며, 본 연구에서는 Pseudomonas sp. NFQ-1으로 명명하였다. Quinoline의 분해는 호기적 조건하의 B-배지에서 Pseudomonas sp. NFQ-1를 이용하여 실시되었다. 균주 NFQ-1 세균은 2.5 mM quinoline을 9시간 이내 완전히 분해하였다. 배양기간 동안 quinoline 분해의 중간대사산물인 2-hydroxyquinoline이 일시적으로 생성되었다가 배양기간 후반부에 사라졌다. 배양의 초기 pH 8.0은 6.8로 감소하다가 배양이 진행됨에 따라 7.0이 되었다. 대상 기질로서 quinoline의 농도가 증가함에 따라 생장곡선에서 유도기가 길어졌으며, 고농도의 quinoline (＞15 mM)은 주어진 조건에서 균주의 생장과 quinoline의 분해를 억제하였다. 부가 질소원으로 7.6 mM $(\textrm{NH}_{4})_{2}\textrm{SO}_{4}$의 첨가조건하에서 Pseudomonas sp. NFQ-1은 2-hydroxyquinoline, p-coumaric acid, benzoic acid, p-cresol, p-hydroxybenzoate, protocatechuic acid, catechol 등의 다양한 화합물을 이용할 수 있었으나 일부 화합물들 (예, 6-hydroxyquinoline, 8-hydroxyquinoline, coumarin, indoline, pyridine, lepidine, quinaldine, 4-bydroxycournarin, benzene, salicylic acid, phenol, phthalate)은 탄소원으로 이용되지 못하였다. euinoline의 분해경로를 규명하기 위하여 catechol dioxygenases의 specific activity를 결정하였다. 그 값은 catechol 1,2-dioxygenase에서 약 184.7 U/mg, 그리고 catechol 1,2-dioxygenase에서 약 33.19 U/mg이었다. 그 결과 균주 NFQ-1은 quinoline를 분해하기 위하여 주로 ortho-분해경로를, 그리고 부분적으로 meta-분해경로를 이용하는 것을 보여주었다.

• 대한의용생체공학회:의공학회지
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• 제19권2호
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• pp.119-128
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• 1998

SPECT 장치는 감마 카메라로 촬영된 일련의 투사영상을 재조합, 재구성하여 횡단면 단층상을 생성하는데, 이때 투사 영상을 획득하는 과정에서 여러 물리적 요소들이 개입되어 투사 영상의 왜곡을 가져온다. 이들 변질 요인들 가운데서도 광자수 제한에 따른 노이즈 변질이 가장 심각한 요인이기 때문에, 투사 영상에 대한 필터링은 노이즈 평활화(smoothing)가 가장 기본적인 방법이다. 그러나 단순한 저역통과 필터링(low-pass filtering)이 투사영상의 윤곽선이나 기타영상구조들을 번지게 함으로써 재구성 영상의 질을 떨어 뜨린다는 사실은 이미 알려져 있다. 주요 영상 구조들을 효과적으로 유지하면서도 노이즈를 억제시키기 위한 한 접근으로 적응적 필터링 기법이 많은 연구자들의 관심을 모으고 있다. 본 논문에서는, 재구성 영상에서의 '최소 검출가능 이상조직의 검출 신뢰도 향상'이라는 관점에서 최적 필터를 설계하였던 이전 연구와 관련하여, 주어진 물리적 조건하에서의 SPECT 이상조직 검출능에 근거된 투사 영상 복원을 위한 적응적 필터링 기법을 제안한다. 결과적으로, 제안된 필터링 알고리즘은 SPECT 영상 재구성시 우수한 이상조직 검출능을 보였으며, 특히 다양한 대조도의 이상조직들을 포함하고 있는 모형 실험에서 보여준 본 필터링 알고리즘의 이상조직 검출능 결과는 실제 SPECT데이터 적응시 좋은 결과를 기대할 수 있게 하였다.

• 콘크리트학회논문집
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• 제20권1호
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• pp.13-22
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• 2008

다공성 시스템 내부 동결체의 생성과 성장은 온도경사와 화학적 에너지뿐만 아니라 열 물리학적 영향과 이동 물질에 의해서도 영향을 받는다. 더욱이 융해 화학물질의 확산율은 반복적인 동경융해 환경 하에서 매우 높은 값을 나타낸다. 결과적으로 콘크리트구조물의 열화는 해양환경과, 높은 고도 및 북쪽 지방에서 특히 크게 발생된다. 그러나 균열 성장과 누적된 손상에 의한 열화를 동반한 동결융해의 특성은 실험을 통해서 추정하기가 곤란하다. 이러한 손상을 예측하기 위해서 응답면기법 (RSM)을 이용한 회귀분석법을 사용하였다. 콘크리트구조물에서 반복되는 동결융해로 인한 열화의 주요 변수인 물-시멘트비, 연행공기, 동결융해의 반복 횟수 등은 응답면기법의 한계상태방정식을 구성하는데 중요한 입력 변수로 사용되었다. 누적변형률, 상대동탄성계수, 또는 등가 소성변형과 같은 주요한 열화 변수에 대한 회귀방정식은 열화된 구조물의 성능을 평가할 수 있다. 300번의 동결융해 반복 후의 상대동탄성계수와 잔류변형의 결과는 실험 결과와 매우 유사한 경향을 나타내었다. 응답면기법의 결과는 설계 시 한계값에 대한 초과 확률을 예측하는데 사용되어질 수 있다. 그러므로 개발된 예측 기법을 활용하여 반복적인 동결융해에 의해서 누적 손상을 받는 콘크리트구조물의 생애주기 관리에 사용될 수 있다.