• Advances in aircraft and spacecraft science
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• 제4권3호
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• pp.281-296
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• 2017

The axial-injection end-burning hybrid rocket proposed twenty years ago by the authors recently recaptured the attention of researchers for its virtues such as no ${\zeta}$ (oxidizer to fuel mass ratio) shift during firing and good throttling characteristics. This paper is the first report verifying these virtues using a laboratory scale motor. There are several requirements for realizing this type of hybrid rocket: 1) high fuel filling rate for obtaining an optimal ${\zeta}$; 2) small port intervals for increasing port merging rate; 3) ports arrayed across the entire fuel section. Because these requirements could not be satisfied by common manufacturing methods, no previous researchers have conducted experiments with this kind of hybrid rocket. Recent advances in high accuracy 3D printing now allow for fuel to be produced that meets these three requirements. The fuel grains used in this study were produced by a high precision light polymerized 3D printer. Each grain consisted of an array of 0.3 mm diameter ports for a fuel filling rate of 98% .The authors conducted several firing tests with various oxidizer mass flow rates and chamber pressures, and analysed the results, including ${\zeta}$ history, using a new reconstruction technique. The results show that ${\zeta}$ remains almost constant throughout tests of varying oxidizer mass flow rates, and that regression rate in the axial direction is a nearly linear function of chamber pressure with a pressure exponent of 0.996.

• ALGAE
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• 제36권3호
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• pp.165-174
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• 2021

Radicilingua Papenfuss and Calonitophyllum Aregood are two small genera of the family Delesseriaceae that consist of only three and one taxonomically accepted species, respectively. The type species of these genera, Radicilingua thysanorhizans from England and Calonitophyllum medium from the Americas, are morphologically very similar, with the only recognized differences being vein size and procarp development. To date, only other two species were recognized inside the genus Radicilingua: R. adriatica and R. reptans. In this study, we analysed specimens of Radicilingua collected in the Adriatic and Ionian Sea (Mediterranean), including a syntype locality of R. adriatica (Trieste, northern Adriatic Sea), alongside material from near the type locality of R. thysanorhizans (Torpoint, Cornwall, UK). The sequences of the rbcL-5P gene fragment here produced represent the first molecular data available for the genus Radicilingua. Phylogenetic reconstruction showed that the specimens from the Adriatic and Ionian Seas were genetically distinct from the Atlantic R. thysanorhizans, even if morphologically overlapping with this species. A detailed morphological description of the Mediterranean specimens, together with an accurate literature search, suggested that they were distinct also from R. adriatica and R. reptans. For these reasons, a new species was here described to encompass the Mediterranean specimens investigated in this study: R. mediterranea Wolf, Sciuto & Sfriso. Moreover, in the rbcL-5P tree, sequences of the genera Radicilingua and Calonitophyllum grouped in a well-supported clade, distinct from the other genera of the subfamily Nitophylloideae, leading us to propose that Calonitophyllum medium should be transferred to Radicilingua.

• 한국ITS학회 논문지
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• 제20권5호
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• pp.45-58
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• 2021

국내에서 운영중인 2차로 회전교차로는 합·분류 등에서 발생하는 상충, 진출·입차량과 회전차량간의 상충 등의 문제점이 있다. 해외에서는 2차로 회전교차로의 문제점을 해결하기 위해 주행경로를 도류화시켜 안전성과 효율성을 향상 시켜주는 나선형 회전교차로를 운영하고 있다. 본 연구에서는 나선형 회전교차로의 국내에 맞는 적정교통량 수준을 분석하기 위해 VISSIM을 이용하여 교통량수준, 방향별 회전교통량을 일정한 수준으로 증가시켰다. 나선형 회전교차로는 방향별 회전교통량에 의해 차이가 있지만 적정교통량은 2,400-2,800대/시인 것으로 분석되었다. 나선형 회전교차로는 좌회전·직진교통량에 의해 지체가 증가하는 것으로 분석되었으며, 좌회전 통행비율이 30% 이상인 경우 나선형 회전교차로보다 2차로 회전교차로와 신호교차로의 운영이 더 효율적인 것으로 분석되었다.

• 한국융합학회논문지
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• 제10권2호
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• pp.207-215
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• 2019

이 연구는 기록관에서 장애인과 비장애인 모두 동등한 수준으로 기록정보서비스를 제공받을 수 있는 환경이 조성되어 있는지를 평가하기 위한 평가지표와 척도를 개발하고자 한다. 장애물 없는 생활환경 인증기준을 기본 틀로 삼되 인증 기준에서 구체적으로 명시하고 있지 않는 기록관의 서비스환경에 관한 항목을 도출하기 위해 기록정보서비스에 대한 개념 분석과 기록관 이용자들의 서비스 동선을 파악한 후 이를 공간별로 항목화하였다. 장애물 없는 생활환경 인증기준, 정보서비스개념과 유형, 서비스 동선과 공간영역 그리고 공공기록물관리법, 국가기록원의 공공기록물서비스 표준들을 모두 융합하여 종합적인 기록정보서비스 환경 평가 지표와 척도를 제시하였다. 이 연구는 궁극적으로 기록관 서비스 환경 평가도구 개발을 통해 기록정보서비스 환경을 객관적으로 평가하고, 이를 통해 서비스제공의 근본 문제점들을 파악한 후, 이를 개선할 수 있는 대안을 제시하고자 한다.

• 복식문화연구
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• 제27권2호
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• pp.140-153
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• 2019

The aim of this study is to develop new wedding dress designs by blending the traditional female Korean upper garment of Han-bok, known as dang-ui, with Western-style wedding dress designs. For this research, the author considered the various types of wedding dresses and their historical development based on literary resources and previous studies of the subject. The results are as follows: first, this study featured the use of different types of fabric for the dang-ui, selected from the various fabrics available for wedding dresses. Starting from the basic design of a sleeveless and strapless princess-line tight top, three different styles of A-line dresses were created: a tiered long dress, an unbalanced tiered midi dress, and a spangled and pleated mini dress. The study also resulted in a tight H-line mini dress with a bustle. In this way, the author was able to suggest new wedding dress styles that are well suited to the cultural trend of the Korean wave. Second, the traditional Korean dang-ui is an elegant ceremonial garment that harmonizes well with Western-style wedding dresses. Satisfaction can be found from combining these creative fusion gowns with traditional Korean aesthetics. Third, the traditional Korean ceremonial coronet jokduri and veil, which go well with dang-ui wedding dresses, are suitable accessories for contemporary wedding dresses. The dang-ui wedding dress, a result of merging the Korean dang-ui and the Western style, will help enhance business for both the Korean and the international wedding industry thanks to an aesthetic that has global appeal.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제45권1호
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• pp.34-42
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• 2019

Objectives: Various bone graft substitute materials are used to enhance bone regeneration in the maxillofacial skeleton. In the recent past, synthetic graft materials have been produced using various synthetic and natural calcium precursors. Very recently, eggshell-derived hydroxyapatite (EHA) has been evaluated as a synthetic bone graft substitute. To assess bone regeneration using EHA in cystic and/or apicectomy defects of the jaws through clinical and radiographic evaluations. Materials and Methods: A total of 20 patients were enrolled in the study protocol (CTRI/2014/12/005340) and were followed up at 4, 8, 12, and 24 weeks to assess the amount of osseous fill through digital radiographs/cone-beam computed tomography along with clinical parameters and complications. Wilcoxon matched pairs test, means, percentages and standard deviations were used for the statistical analysis. Results: The sizes of the lesions in the study ranged from 1 to 4 cm and involved one to four teeth. The study showed significant changes in the formation of bone, the merging of material and the surgical site margins from the first week to the first month in all patients (age range, 15-50 years) irrespective of the size of the lesions and the number of teeth involved. Bone formation was statistically significant from the fourth to the eighth week, and the trabecular pattern was observed by the end of 12 weeks with uneventful wound healing. Conclusion: EHA showed enhancement of bone regeneration, and healing was complete by the end of 12 weeks with a trabecular pattern in all patients irrespective of the size of the lesion involved. The study showed enhancement of bone regeneration in the early bone formative stage within 12 weeks after grafting. EHA is cost effective and production is environment friendly with no disease transfer risks. Thus, natural bioceramics will play an important role in the reduction of costs involved in grafting and reconstruction.

• 한국정보통신학회논문지
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• 제22권11호
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• pp.1524-1530
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• 2018

본 논문에서는 중고 스마트폰을 세계 최초로 IoT 사물통신기술과 융합하여 그린 IT 솔루션을 상용화함으로써 환경오염과 자원낭비 및 외화유출을 막을 수 있는 제품으로 설계하였다. 제안한 시스템의 실험을 위하여 실제 농작물 재배 시설내에 설치하여 여러 가지 기능과 통신 상태를 실험하였다. 그 결과 문제점이 발생될 경우에 사용자의 스마트폰으로 경보음 및 동영상 알림이 발생되며, 또한 각종 설치된 기기들의 원격제어와 실시간으로 데이터 분석이 가능하였다. 본 연구에서 중고 스마트폰의 활용을 위해 개발된 단말기 관리보드는 농업이나 환경 등의 다양한 분야에 응용이 가능하리라 사료된다.

• 한국분무공학회지
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• 제23권4호
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• pp.192-204
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• 2018

In this study, a 3D CFD analysis method for the combustion process was established for a low calorific value syngas-diesel dual-fuel engine operating under very lean fuel-air mixture condition. Also, the accuracy of computational analysis was evaluated by comparing the experimental results with the computed ones. To simulate the combustion for the dual-fuel engine, a new dual-fuel chemical kinetics set was used that was constituted by merging two verified chemical kinetic sets: n-heptane (173 species) for diesel and Gri-mech 3.0 (53 species) for syngas. For dual-fuel mode operations, the early stage of combustion was dominated by the fuel burning inside or near the spray plume. After which, the flame propagated into the syngas in the piston bowl and then proceeded toward the syngas in the squish zone. With the baseline injection system and piston shape, a significant amount of unburned syngas was discharged. To solve this problem, effects of the injection parameters and piston shape on combustion characteristics were analyzed by calculation. The change in injection variables toward increasing the spray plume volume or the penetration length were effective to cause fast burning in the vicinity of TDC by widening the spatial distribution of diesel acting as a seed of auto-ignition. As a result, the unburned syngas fraction was reduced. Changing the piston shape with the shallow depth of the piston bowl and 20% squish area ratio had a significant effect on the combustion pattern and lessened the unburned syngas fraction by half.

• Advances in Computational Design
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• 제4권2호
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• pp.155-177
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• 2019

Operation and Maintenance (O&M) phase is the main contributor to the total lifecycle cost of a building. Previous studies have described that Building Information Models (BIM), if available with detailed asset information and their properties, can enable rapid troubleshooting and execution of O&M tasks by providing the required information of the facility. Despite the potential benefits, there is still rarely BIM with Mechanical, Electrical and Plumbing (MEP) assets and properties that are available for O&M. BIM is usually not in possession for existing buildings and generating BIM manually is a time-consuming process. Hence, there is a need for an automated approach that can reconstruct the MEP systems in BIM. Previous studies investigated automatic reconstruction of BIM using architectural drawings, structural drawings, or the combination with photos. But most of the previous studies are limited to reconstruct the architectural and structural components. Note that mechanical components in the building typically require more frequent maintenance than architectural or structural components. However, the building mechanical drawings are relatively more complex due to various type of symbols that are used to represent the mechanical systems. In order to address this challenge, this paper proposed a symbol recognition framework that can automatically recognize the different type of symbols in the building mechanical drawings. This study applied vector-based computer vision techniques to recognize the symbols and their properties (e.g., location, type, etc.) in two vector-based input documents: 2D drawings and the symbol description document. The framework not only enables recognizing and locating the mechanical component of interest for BIM reconstruction purpose but opens the possibility of merging the updated information into the current BIM in the future reducing the time of repeated manual creation of BIM after every renovation project.

• 한국정보기술학회논문지
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• 제16권12호
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• pp.85-92
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• 2018

복잡한 영상처리 알고리즘을 사용할 때 계산량을 줄이기 위해 슈퍼픽셀을 사용한다. 슈퍼픽셀은 특성이 유사한 픽셀들을 군집화하여 하나의 그룹으로 만드는 방법이다. 슈퍼픽셀은 영상처리의 전단계로 사용되기 때문에 빠르게 생성할 수 있어야 하고 영상의 에지 성분들을 잘 보존하여야 한다. 본 논문에서는 에지 성분을 잘 보존하면서도 계산량이 많지 않은 슈퍼픽셀 생성 방법을 제안한다. 제안하는 방법에서는 먼저 기존의 k-mean 방법을 이용하여 영상의 슈퍼픽셀을 충분히 생성하고, 생성된 슈퍼픽셀들을 분석하여 유사한 슈퍼픽셀을 병합하는 방식으로 최종 슈퍼픽셀을 생성한다. 슈퍼픽셀을 병합할 때는 슈퍼픽셀에 대해서만 유사도를 측정하기 때문에 추가되는 계산량은 많지 않다. 실험 결과는 제안하는 방법으로 생성된 슈퍼픽셀이 기존 방법에 의해 생성된 슈퍼픽셀에 비해 보다 정확하게 에지 성분들을 보존하는 것을 보여준다.