근사기법에 의한 격자구성

윤용현 空軍士官學校 1992 論文集 Vol.31 No.-

최근 전산 유체역학은 복잡한 유체 흐름형상에 대해서도 매우 신뢰할만한 결과를 얻을 만큼 유동장을 시뮬레이션해가고 있다. 이러한 복잡한 유동형상을 유체역학의 지배방정식으로 수치 해석하는데 있어서 격자구성(Grid Generation)이 매우 중요한 요소로써 대부분의 시뮬레이션 작업시간을 차지하고 있다. 최근 몇 년 사이에 근사기법에 의한 격자구성기법이 개발되면서 매우 복잡한 유동장을 대상으로 격자 구성하는데 편리함을 보여주고 있다. 이 근사기법에 의해 유동장을 모델링하고 표면격자를 형성하여 이 기법의 유용성을 보여주고 있다.

방사힘 측정법을 이용한 초음파 진단장치용 배열 탐침자의 음향파워 측정시스템

윤용현,조문재,김용태,이명호,Yun, Yong-Hyeon,Jho, Moon-Jae,Kim, Yong-Tae,Lee, Myoung-Ho 한국음향학회 2010 韓國音響學會誌 Vol.29 No.6

초음파 진단장치의 음향출력 특성은 전기음향 변환 장치인 배열 탐침자의 성능에 크게 영향을 받으며, 생물학적안전 측면에서 매우 중요하다. 본 논문에서는 초음파 진단장치용 배열 탐침자로부터 방사되는 음향파워를 소자별로 측정할 수 있는 자동화 시스템을 구성하였으며, 곡선형 탐침자의 경우 각 소자의 지향성이 측정에 미치는 영향을 확인하고 이를 보정하는 기법을 개발하였다. 선형, 위상형, 곡선형 배열 탐침자를 대상으로 음향파워 측정결과, 본 논문에서 제시하는 측정기법은 배열 탐침자의 음향파워 특성을 평가하는데 적합함을 확인하였다. Considering biological safety, it is very important to measure acoustic power from ultrasonic array probe for diagnostic ultrasound imaging applications. In this paper, to measure acoustic power from each element on array probe for ultrasonic diagnostic equipment, we reconstruct and automate the acoustic power measurement system. The acoustic power from linear, phased and curved array were measured and analyzed. As a result of measurement, the effects caused by directivity of sound beam from curved array were founded. To remove these effects, we developed and applied the correction model. The proposed system is useful to evaluate characteristics of the acoustical output power of array probe.

항공무장 안전분리 검증을 위한 풍동실험연구

윤용현,백승욱,조환기,정형석,조동현 한국항공우주학회 2007 한국항공우주학회 학술발표회 논문집 Vol.- No.-

토제 거푸집 무쇠솥 주조와 불미기술 연구

윤용현,도정만,정영상 국립문화재연구원 2020 헤리티지:역사와 과학 Vol.53 No.2

The purpose of this study was to explore the diversity of Korea’s iron casting technology and to examine variouscasting methods. The study involved a literature review, analysis of artifacts, local investigation of production toolsand technology, and scientific analysis of casting and cast materials. Bellows technology, or Bulmi technology, is a form of iron casting technology that uses bellows to melt cast ironbefore the molten iron is poured into a clay cast. This technology, handed down only in Jeju Island, relies on use of aclay cast instead of the sand cast that is more common in mainland Korea. Casting methods for cast iron pots can be broadly divided into two: sand mold casting and porcelain casting. Theformer uses a sand cast made from mixing seokbire (clay mixed with soft stones), sand and clay, while the latter usesa clay cast, formed by mixing clay with rice straw and reed. The five steps in the sand mold casting method for ironpot are cast making, filling, melting iron into molten iron, pouring the molten iron into the cast mold, and refiningthe final product. The six steps in the porcelain clay casting method are cast making, cast firing, spreading jilmeok,melting iron into molten iron, pouring the molten iron, and refining the final product. The two casting methodsdiffer in terms of materials, cast firing, and spreading of jilmeok. This study provided insight into Korea’s unique iron casting technology by examining the scientific principlesbehind the materials and tools used in each stage of iron pot casting: collecting and kneading mud, producing a cast,biscuit firing, hwajeokmosal (building sand on the heated cast) and spreading jilmeok, drying and biyaljil (spreadingjilmeok evenly on the cast), hapjang (combining two half-sized casts to make one complete cast), producing asmelting furnace, roasting twice, smelting, pouring molten iron into a cast, and refining the final product. Scientific analysis of the final product and materials involved in porcelain clay casting showed that the maincomponents were mud and sand (SiO2, Al2O3, and Fe2O3). The release agent was found to be graphite, containingSiO2, Al2O3, Fe2O3, and K2O. The completed cast iron pot had the structure of white cast iron, comprised ofcementite (Fe3C) and pearlite (a layered structure of ferrite and cementite).

단분리 미사일 기저면의 유동장 해석

윤용현,권기범 한국항공우주학회 2006 한국항공우주학회 학술발표회 논문집 Vol.- No.-

인간/기계 형상의 컴퓨터 표현기법 ( Computational Representative Techniques of Human/Machine Configurations )

윤용현 대한인간공학회 1992 대한인간공학회 학술대회논문집 Vol.1992-2 No.-

조선왕실 주조 금속활자 복원활자의 과학 분석

윤용현 한국서지학회 2007 서지학연구 Vol.38 No.-

NURBS를 이용한 형상 모델링에 관한 연구

윤용현,김진식 한국항공우주학회 1999 한국항공우주학회 학술발표회 논문집 Vol.- No.-

RC모형기를 이용한 보라호의 비행실험

윤용현,이종원,김응태,한창환,안석민 한국항공우주학회 2002 한국항공우주학회 학술발표회 논문집 Vol.- No.-

조선 전기 자동물시계의 주전(籌箭) 연구

윤용현,김상혁,민병희,오경택 한국천문학회 2021 天文學論叢 Vol.36 No.3

Jagyeokru, an automatic striking water clock described in the Sejong Sillok (Veritable Records of King Sejong) is essentially composed of a water quantity control device and a time-signal device, with the former controlling the amount or the flow rate of water and the latter automatically informing the time based on the former. What connects these two parts is a signal generating device or a power transmission device called the ‘Jujeon’ system, which includes a copper rod on the float and ball-racked scheduled plates. The copper products excavated under Gongpyeong-dong in Seoul include a lot of broken plate pieces and cylinder-like devices. If some plate pieces are put together, a large square plate with circular holes located in a zigzag can be completed, and at the upper right of it is carved ‘the first scheduled plate (一箭).’ Cylinder-like devices generally 3.8 cm in diameter are able to release a ball, and have a ginkgo leaf-like screen fixed on the inner axis and a bird-shaped hook of which the leg fixes another axis and the beak attaches to the leaf side. The lateral view of this cylinder-like device appears like a trapezoid and mounts an iron ball. The function of releasing a ball agrees with the description of Borugak Pavilion, where Jagyeokru was installed, written by Kim Don (1385 ~ 1440). The other accounts of Borugak Pavilion’s and Heumgyeonggak Pavilion’s water clocks describe these copper plates and ball releasing devices as the ‘Jujeon’ system. According to the description of Borugak Pavilion, a square wooden column has copper plates on the left and right sides the same height as the column, and the left copper plate has 12 drilled holes to keep the time of a 12 double-hours. Meanwhile, the right plate has 25 holes which represent seasonal night 5-hours (Kyeong) and their 5-subhours (Jeom), not 12 hours. There are 11 scheduled plates for seasonal night 5-hours made with copper, which are made to be attached or detached as the season. In accordance with Nujutongui (manual for the operation of the yardstick for the clepsydra), the first scheduled plate for the night is used from the winter solstice (冬至) to 2 days after Daehan (大寒), and from 4 days before Soseol (小雪) to a day before the winter solstice. Besides the first scheduled plate, we confirm discovering a third scheduled plate and a sixth scheduled plate among the excavated copper materials based on the spacing between holes. On the other hand, the width of the scheduled plate is different for these artifacts, measured as 144 mm compared to the description of the Borugak Pavilion, which is recorded as 51 mm. From this perspective, they may be the scheduled plates for the Heumgyeonggak Ongru made in 1438 (or 1554) or for the new Fortress Pavilion installed in Changdeokgung palace completed in 1536 (the 31st year of the reign of King Jungjong) in the early Joseon dynasty. This study presents the concept of the scheduled plates described in the literature, including their new operating mechanism. In addition, a detailed model of 11 scheduled plates is designed from the records and on the excavated relics. It is expected that this study will aid in efforts to restore and reconstruct the automatic water clocks of the early Joseon dynasty.