• 한국항공우주학회지
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• 제37권6호
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• pp.562-570
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• 2009

불어내기식 극초음속 풍동을 이용하여 2차원형 돌출물 주위의 유동 및 공력가열 특성에 대한 실험적 연구를 수행하였다. 실험의 유입 유동 조건은 마하수 7, 단위 레이놀즈수 $2.0{\times}10^6/m$ 이다. 실험 조건은 길이가 다른 두 개의 평판에 세 가지 돌출물이 높이에 따라 변화되며, 실험데이터는 쉴리렌 이미지 가시화 기법과 돌출물 전면에서의 열유속 게이지를 이용한 열유속 측정을 통해 획득되었다. 또한, 본 논문에서는 경계층 천이 탐지기법과 같은 극초음속 유동 실험 기법도 함께 제시하였다. 실험 결과 돌출물 전방에 큰 박리 영역이 관찰되었으며, 박리 영역은 돌출물의 높이와 평판의 길이에 따라 민감하게 변화 하였다. 가장 큰 돌출물의 경우에서만, 돌출물 상부 측정점에서 열유속 측정치의 급격한 점프가 있는 것으로 관찰되었다. 또한 측정된 열유속은 돌출물의 높이가 크고 평판의 길이가 길수록 증가하는 경향성을 보였다.

• Investigative Magnetic Resonance Imaging
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• 제22권4호
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• pp.209-217
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• 2018

Purpose: The objective of this study was to obtain improved susceptibility weighted images (SWI) of the cervical spinal cord using respiratory-induced artifact compensation. Materials and Methods: The artifact from $B_0$ fluctuations by respiration could be compensated using a double navigator echo approach. The two navigators were inserted in an SWI sequence before and after the image readouts. The $B_0$ fluctuation was measured by each navigator echoes, and the inverse of the fluctuation was applied to eliminate the artifact from fluctuation. The degree of compensation was quantified using a quality index (QI) term for compensated imaging using each navigator. Also, the effect of compensation was analyzed according to the position of the spinal cord using QI values. Results: Compensation using navigator echo gave the improved visualization of SWI in cervical spinal cord compared to non-compensated images. Before compensation, images were influenced by artificial noise from motion in both the superior (QI = 0.031) and inferior (QI = 0.043) regions. In most parts of the superior regions, the second navigator resulted in better quality (QI = 0.024, P < 0.01) compared to the first navigator, but in the inferior regions the first navigator showed better quality (QI = 0.033, P < 0.01) after correction. Conclusion: Motion compensation using a double navigator method can increase the improvement of the SWI in the cervical spinal cord. The proposed method makes SWI a useful tool for the diagnosis of spinal cord injury by reducing respiratory-induced artifact.

• Clinics in Shoulder and Elbow
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• 제22권3호
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• pp.135-138
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• 2019

Background: The aims of this study were (1) to examine the footprint of the subscapularis tendon using the traditional posterior portal and $30^{\circ}$ arthroscope by simple internal rotation of the arm during surgery, and (2) to classify the pattern of a subscapularis partial-thickness tear. Methods: This study analyzed a total of 231 patients with a partial-thickness subscapularis tear from 550 consecutive patients undergoing an arthroscopic operation who had a visualization of the subscapularis tendon footprint by internal rotation of the arm. First, the patients were classified into four categories according to the tear pattern: (1) stable lamination, (2) unstable lamination, (3) avulsion, and (4) laminated avulsion. Randomized arthroscopic videos were reviewed blindly by two independent orthopedic surgeons. The pattern of the tear of the subscapularis at the neutral position and after internal rotating the arm were assessed and compared with the treatment decision (level IV case series). Results: Stable lamination, unstable lamination, avulsion, and laminated avulsion were observed in 9.1% (n=21), 20.8% (n=48), 41.1% (n=95), and 29.0% (n=67) of cases, respectively. In 145 out of 231 cases (62.8%), the decision was changed after inspecting the footprint after internal rotation of the arm, and the treatment method was changed in 116 (50.2%) cases. Conclusions: In a subscapularis tendon partial-thickness tear, inspecting the footprint of the subscapularis tendon is essential to diagnosing and deciding on the appropriate treatment. In addition, simply internal rotating the arm during surgery when using the traditional posterior portal and $30^{\circ}$ arthroscope can be a valuable method.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3855-3863
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• 2022

An evaluation of the radiation shielding performance of high-Z-particle-loaded polylactic acid (PLA) composite materials was pursued. Specimens were produced via fused deposition modeling (FDM) using copper-PLA, steel-PLA, and BaSO₄-PLA composite filaments containing 82.7, 75.2, and 44.6 wt% particulate phase contents, respectively, and were tested under broad-band flash x-ray conditions at the Sandia National Laboratories HERMES III facility. The experimental results for the mass attenuation coefficients of the composites were found to be in good agreement with GEANT4 simulations carried out using the same exposure conditions and an atomistic mixture as a model for the composite materials. Further simulation studies, focusing on the Cu-PLA composite system, were used to explore a shield design parameter space (in this case, defined by Cu-particle loading and shield areal density) to assess performance under both high-energy photon and electron fluxes over an incident energy range of 0.5-15 MeV. Based on these results, a method is proposed that can assist in the visualization and isolation of shield parameter coordinate sets that optimize performance under targeted radiation characteristics (type, energy). For electron flux shielding, an empirical relationship was found between areal density (AD), electron energy (E), composition and performance. In cases where ${\frac{E}{AD}}{\geq}2MeV{\bullet}cm{\bullet}g^{-1}$, a shield composed of >85 wt% Cu results in optimal performance. In contrast, a shield composed of <10 wt% Cu is anticipated to perform best against electron irradiation when ${\frac{E}{AD}}<2MeV{\bullet}cm{\bullet}g^{-1}$.

• 한국건설관리학회논문집
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• 제24권2호
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• pp.3-12
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• 2023

건축물에서 발생하는 화재 사고는 주변에서 빈번하게 확인할 수 있는 문제이다. 건축물의 화재사고는 시간의 경과에 따라 인적·물적 자원의 피해가 커지고 대형사고로 이어지게 됨으로 신속한 화재 진압·구조 방안의 모색이 필요하다. 현재 사회적으로도 화재 사고에 관한 관심은 주목되고 있으나 실제 화재 상황에 대처하는 부분에 미흡함이 존재해 안전사고에 관하여 사회가 요구하는 기대치를 충족하지 못하는 실정이다. 이러한 사회의 요구에 맞추어 본 연구는 건물 내 화재로 인한 피해를 최소화하기 위한 신속하고 체계적인 화재 관리 방안을 제시하고 있다. 연구의 목적을 달성시키기 위한 방안으로 아두이노 센서 및 Excel, Revit-Dynamo 툴을 연동하여 새로운 화재정보 관리 시스템을 개발 및 실시간 3D 시각화 Model을 개발하고, 실제 사례에 적용하여 화재 관리의 우수성을 보였다. 추후 활용방안으로 화재 관리 어플리케이션을 제안하여 실시간 스마트 화재 관리시스템에 기여할 수 있다고 기대하는 바이다.

• 조형예술학연구
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• 제8권
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• pp.63-94
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• 2005

ChangSayng-Do in the late Chosun dynasty was a kind of traditional painting which sublimated the philosophy and emotion of everyday life into an aesthetic consciousness through a long history of Korean people . It would represent a human wish and desire to live a long and healthy life, which was implicated by way of Taoism. The major themes of ChangSayng-Do - mountains, the sun, cloud, water, rock, deer, tortoises, cranes, pine trees, bamboos, peaches, and herbs of eternal youth - were all symbols used. to wish for a long-life and immortality in real world. All or some of these items were represented in paintings, which resulted in the various kinds of ChangSayng-Do. The main concern of this thesis will be centered around the naturalistic subjects shown in ChangSayng-Do. This thesis consists of four chapters. The first chapter describes the purpose of and need for the research, and its method and scope. The second chapter deals with the origin and style of ChangSayng-Do, and the background of its formation. It is found out that the formative characteristic of ChangSayng-Do lies in the archetype, the unity of man and nature following the traditional view of nature. It is also found out that ChangSayng-Do implied the notions of Supernatural Being, Yin-Yang and Five Elements, Taoism, and Confucianism as well as Korean shamanism. Third chapter is largely about an analytic investigation into symbolic visualization of ChangSayng-Do. Firstly, the subject matters shown in ChangSayng-Do consist of items of wishful omen for long-life and good luck, and any motif in a picture implies a symbolism of eternal youth and long-life. Secondly, the view of colors shown in ChangSayng-Do is closely connected to Five Elements and Five Direction, a traditional oriental philosophy of universe, and these symbolic colors are based on shamanism and Yin/Yang-Five Elements. According to an iconological analysis, it is confirmed that these viewpoints are consistent with formative principles and expressive methods of ChangSayng-Do to some extent. The fourth chapter is one of the most important elements for visualization of ChangSayng-Do. The symbolic meaning of long life and good luck is the major source of its popularity inside the palace as well as among the people in general. The fact that ChangSayng-Do was used to ornament the palace was documented in $\lceil$UiGuey(documents about Chosun dynasty$\rfloor$. Also during the late period of Chosun dynasty, the appreciators of arts had begun to spread from high level class to lower level class, and many pictures represented in $\lceil$Hanyang-Ga$\rfloor$ were the ones produced and circulated for those increased consumers. As for the folk-artistic characteristics, the anonymity and arbitrary naturalness of ChangSayng-Do demonstrates that the folk-artistic elements were fully soaked into the life styles of people in general. ChangSayng-Do further shows that a human being is located in the center of the universe, and that all the natural phenomena and ecology are observed to happen around human beings, and that the results of those happenings are connected to man's course of life. It is discovered that the subject matters of ChangSayng-Do in the late Chosun dynasty imply another idea inside metaphors and symbols. With regard to the arrangement of time and space, the unity or oneness of oneself with the world is more highly regarded than one's individual subjectivity: there exist multiple times and spaces in a single picture This reveals a wholistic view of oneness which does not permit the division between phenomenon and substance. To conclude, this thesis inquired into ChangSayng-Do in the late Chosun dynasty focusing on the expression of archetype-symbols. And through the analysis and demonstration, this thesis re-established constructional principles and formative characteristics of ChangSayng-Do and then settled a new phase of ChangSayng-Do, with a deep under-standing of fundamental thoughts of Korean people underlying ChangSayng-Do.

• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1180-1186
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• 2009

이 실험적인 연구는 오픈 캐비티에서 경사후방벽면을 가지고 있는 유동장안의 제어봉이 있고 없음과 제어봉의 위치에 따른 유동 내부특성을 알고자 하였다. 속도 측정법으로는 흐름과 입자 영상의 가시화가 가능한 PIV기법을 이용하여 레이놀즈수의 변화와 속도에 대하여 고찰하였다. 제어봉의 어느 위치가 캐비티 내부유동 특성에 영향을 적게 주며, 전단 혼합 층이 유동장 상부와 하류 쪽으로 이동하는지에 대한 레이놀즈수의 임계점을 알고자 하였다.그 결과, 제어봉의 위치 L/H=0.2에서, 제어봉의 위치를 각각 상이하게 정하여 보았으나, L/H=0.2의 경우가 가장 캐비티에 영향을 적게 주는 것으로 판단된다. 주와류 후방의 흐름이 상부로 서서히 치우쳐 있으며 레이놀즈수가 증가할수록 이러한 현상은 뚜렷해지고, 이것은 y/H=1.0 전후의 주 흐름은 제어봉의 효과로 캐비티 상부에 발생한 주 와류의 위쪽으로 치우쳐 하류로 진행하기 때문으로 판단된다. 이러한 현상은 레이놀즈수가 증가하면서 더욱 뚜렷해지며 그 임계점은 $Re=1.0{\times}10^4$전후임을 알 수 있었다. 제어봉의 위치가 L/H=0.1의 경우 레이놀즈수의 증가 ($Re=6.0{\times}10^3$, $Re=8.0{\times}10^3$, $Re=1.0{\times}10^4$, $Re=1.2{\times}10^4$)에 따라 상부에 이중와류 구조가 발생하고, 캐비티 상부의 전단 혼합 층이 증가함에 따라 하단부의 속도분포가 더 안정적인 모습도 알 수 있었다.

• 한국화재소방학회논문지
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• 제15권1호
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• pp.1-6
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• 2001

본 연구는 터널내 화재발생시 자연 배기에 의한 연기의 거동을 해석하기 위하여 축소모형 실험을 수행하였다. 터널내 연기의 유동은 부력에 의해 지배되므로 Froude scaling에 의해 실물 터널을 1/20로 축소한 모형터널에서 실험을 수행하였으며 배기구의 위치변화에 따른 영향을 평가하기 위하여 화원으로부터 각각 1m, 2m, 3m 떨어진 곳에 배기구를 대칭으로 위치시켜 세가지 경우에 대해 실험을 실시하였다. 지름이 4.36 cm인 화원의 경우, 배기구의 위치에 관계없이 배기구 통과 후 연층의 온도가 배기를 실시하지 않은 경우와 비교하여 약 7~$8^{\circ}$ 낮게 유지되었다. 지름이 5.23cm인 화원의 경우, 배기구가 화원에 가까울수록 배기구 통과 후 연기의 평균속도가 감소하였으며 최대 3.86초가 지연되었다. CASE 1에서는 배기구 통과 후 천장에서 약 $8^{\circ}c$, 수직온도가 약 $7^{\circ}c$ 감소하였으며, CASE 2에서는 천장과 수직온도가 약 $3^{\circ}c$ 감소하였으며, CASE 3에서는 각각 약 $2^{\circ}c$가 감소하였다. 레이저와 디지털 캠코더를 이용하여 배기구 주위의 연기 유동을 가시화하여 화재발생 약 1분 후부터 연층의 두께가 터널높이의 25%이하로 일정하게 유지되는 것을 확인할 수 있었다.

• 전자공학회논문지
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• 제54권3호
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• pp.78-86
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• 2017

본 논문에서는 은폐 물체 탐지를 위해 인체에 무해한 음향신호 중 파라메트릭 배열을 이용한 음향 탐지 시스템을 제안한다. 제안된 탐지 시스템은 파라메트릭 배열 현상으로부터 생성되는 고 지향성 Chirp 신호를 송신신호로 사용하고, Dechirp 처리 과정을 통해 수신신호의 신호 대 잡음비를 개선하여 거리 분해능을 향상시키는 기법을 사용한다. 제안된 파라메트릭 배열 시스템의 송신센서는 $8{\times}2$ 배열로 구축하였으며, 센서 배열의 빔 폭은 수평방향 약 $7^{\circ}$와 수직방향 약 $26^{\circ}$를 형성한다. 제안된 시스템을 검증하기 위해 물체 탐지 및 가시화를 위한 2축 구동 제어 선형 스테이지를 구축하였으며, 이를 이용하여 은폐된 물체에 대한 A-scan, B-scan 및 C-scan 실험을 진행하였다. 실험 결과, 천에 은폐된 동판과 파이프를 탐지하고 형상을 확인하였으며, 가시화된 형상에서 동판은 $0.015m^2$, 파이프는 $0.046m^2$의 오차를 보여주었다.

• Toxicological Research
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• 제32권1호
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• pp.81-87
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• 2016

Aflatoxin B1 (AFB1) is produced by Aspergillus flavus growing in feedstuffs. Early detection of maize contamination by aflatoxigenic fungi is advantageous since aflatoxins exert adverse health effects. In this study, we report the development of an optimized conventional PCR for AFB1 detection and a rapid, sensitive and simple screening Real-time PCR (qPCR) with SYBR Green and two pairs of primers targeting the aflR genes which involved aflatoxin biosynthesis. AFB1 contaminated maize samples were divided into three groups by the toxin concentration. Genomic DNA was extracted from those samples. The target genes for A. flavus were tested by conventional PCR and the PCR products were analyzed by electrophoresis. A conventional PCR was carried out as nested PCR to verify the gene amplicon sizes. PCR-RFLP patterns, obtained with Hinc II and Pvu II enzyme analysis showed the differences to distinguish aflatoxin-producing fungi. However, they are not quantitative and need a separation of the products on gel and their visualization under UV light. On the other hand, qPCR facilitates the monitoring of the reaction as it progresses. It does not require post-PCR handling, which reduces the risk of cross-contamination and handling errors. It results in a much faster throughout. We found that the optimal primer annealing temperature was $65^{\circ}C$. The optimized template and primer concentration were $1.5{\mu}L\;(50ng/{\mu}L)$ and $3{\mu}L\;(10{\mu}M/{\mu}L)$ respectively. SYBR Green qPCR of four genes demonstrated amplification curves and melting peaks for tub1, afIM, afIR, and afID genes are at $88.0^{\circ}C$, $87.5^{\circ}C$, $83.5^{\circ}C$, and $89.5^{\circ}C$ respectively. Consequently, it was found that the four primers had elevated annealing temperatures, nevertheless it is desirable since it enhances the DNA binding specificity of the dye. New qPCR protocol could be employed for the determination of aflatoxin content in feedstuff samples.