Relationship Between Fluid Flow Stability and Submerged Entry Nozzle Port Angle in a Conventional Slab Continuous-Casting Mold

Won‑hyuk Lee,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

Fluid flow patterns within a conventional slab continuous-casting mold are closely linked to the port angle of the submergedentry nozzle (SEN). Fluid flow is unstable below a certain port angle, with large fluctuations near the port outlet as wellas jet stream oscillation and repeated vortex formation and dissipation within the mold. However, such phenomena are notobserved above a certain port angle, at which the flow pattern becomes stable. This behavior was investigated via bothnumerical simulation and water model experimentation; two different regions were identified with flow patterns varyingaccording to the SEN port angle. In addition, a close quantitative relationship was identified between changes in the portangle and fluid velocity variations. For SEN port angles in the range 0°–15°, the flow velocity in the upper circulation zoneoscillated in an unstable manner. For port angles of 20° or more, the flow velocity of the same zone decreased significantlyand stabilized. When the gas was injected, the unstable region elongated to 0°–20°. The present study offers insight towarddeveloping a clearer understanding of the complex flow patterns in casting molds, as well as of the conditions necessary forstable flow patterns.

수열합성법에 의한 MLCC용 구형 니켈분말 제조

원창환,이종현,원형일,이혁희 대한금속ᆞ재료학회 2006 대한금속·재료학회지 Vol.44 No.3

狩獵人의 意識 및 行態에 關한 硏究

邊雨爀,金源明 高麗大學校 自然資源科學硏究所 1996 自然資源科學硏究 Vol.4 No.-

The purpose of this study is to investigate hunter's consciousness and the behavior of hunting activities, thereby proposing primary information of decision-making hunting polices and regulation which are based to manage wildlife resource. Data for this study were obtained from available 809 among 3,424 questionares delivered to hunters who have gone hunting to chungbuk hunting preserve in 1990. The results of study are as follow, most of the hunters who are good scholar and earn a large income and are the middle-aged, are influential members of the society as a whole. The 48.2% of hunters were unsatisfied with this hunting trip, because of coming home with poor bag and the fear of illegal traps. Hunters thought the density of wildlife population was very low, and the bag was dependent in hunter's hunting ability. Hunters thought that their ability of according to hunting laws and regulations and discrimination power of wildlife were more developing hunting preserve, hunter's education, hunting trust, revicement hunting law, and enforcement hunting agent are need to enrichment hunting culture and economics.

薄肉鑄物의 硬度및組織에 미치는 鑄物砂의 影響

李載元,權赫茂 충남대학교 공업기술개발연구소 1975 工業技術開發硏究所論文集 Vol.2 No.2

The effects of molding sand permeability on the graphite structure and the hardness in the thin casting ranging from one to ten milimeters in thickness molded with several kinds of carbon equivalent of cast iron were studied and the following results are obtained; (1) In accordance with the increasing of molding sand permeability in the thin casting. (a) the graphite sizes were refined in every specimen experimented (b) the hardnesses of the thin castings ranging from two to ten milimeters in thickness were increased. (2) It is recommendable to use the hypereutectic melt for the thin cast about one milimeter in thickness because of both eutectic and hypoeutectic melt cause the chilled cast and the increase of hardness regardless of the changes in molding sand permeability.

Arthroscope 시스템 설계에 관한 연구

장민혁,김형범,김태옥,양원일,박종안 朝鮮大學校 電子情報通信硏究所 2004 電子情報通信硏究所論文集 Vol.7 No.2

본 연구에서는 관절 내시경 시스템 개발을 목표로 임상 교수들의 조언과 사용자의 편의를 우선으로 하는 PC기반 GUI 형태의 관절 내시경 시스템 설계에 초점을 맞추어 연구하였다. 관절 내시경 시스템의 성능 향상을 위한 모듈 설계하여 검증을 통한 시험 및 시뮬레이션 분석을 하였다. 또한 임상 교수의 관절 내시경 시스템 개발 참여로 사용자 중심의 편리한 시스템 구성 및 관련 H/W 및 S/W 기술 축적뿐만 아니라 PC기반 GUI 형태의 윈도우 S/W 개발로 해외 시장개척을 위한 경쟁력이 강화될 것으로 기대된다.

신경망을 이용한 적응잡음제거기 설계

곽우혁,최한고,박원우 金烏工科大學校 1998 論文集 Vol.19 No.-

This paper describes a nonlinear adaptive noise canceller using neural networks as the nonlinear adaptive filter, which is suitable for extracting periodic signals and nonstationary signals contaminated with broadband noise. Two neural networks. feedforward (FNN) and recurrent neural networks (RNN), are used as nonlinear adaptive filters. In this paper, it assumes that the noise of the primary input in the adaptive noise canceller is not the same characteristic as that of the reference input. Performance of the proposed noise canceller is evaluated using peripdic sawtooth signal and speech signal with white noise, and than compared with conventional adaptive noise canceller of linear structure. Experimental results show that the neural network based noise canceller outperforms the linear noise canceller. It is also verified that the RNN adaptive filer performs best with respect to noise rejection of mean square error.

신경회로망을 이용한 원공 결함 패턴 인식에 관한 연구

홍순혁,이동우,허건,조석수,주원식 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.1

Ultrasonic inspection of defects has been focused on the existence of defect in structural material and need has much time and expenses in inspecting all the coordinates (x, y) on material surface. Neural networks is information processing system modeling human brain and can have an application to coordinates (x, y) of defects by multi-point inspection method. Ultrasonic inspection modeling is optimized by neural networks which makes defect echo, back-wall echo and ultrasonic transducer units of input layer and absolute and relative coordinates of defects and defect pattern units of output layer. This method can predict coordinates (x, y) of defects within engineering estimated mean error Ψ.

클로르헥시딘 바니쉬의 적용이 교정용 브라켓의 전단접착강도에 미치는 영향

임동혁,김태우,장영일,남동석,양원식,백승학 대한치과교정학회 2000 대한치과교정학회지 Vol.30 No.2

본 연구의 목적은 클로르헥시딘 처리가 교정용 브라켓의 전단접착강도와 탈락 양상에 미치는 영향을 비교하는 것이다. 실험군으로 4주간 4회의 클로르헥시딘 바니쉬를 도포한 22개의 사람 소구치를 선택하였고, 대조군으로 아무 처리도 하지 않은 22개의 사람 소구치를 선택하였다. 모든 치아는 37%의 phosphoric acid gel로 부식시키고 교정용 브라켓을 같은 조건으로 부착시켰다. 전단접착강도의 측정을 위해 Instron universal testing machine(model 4466)을 이용하였고, 법랑질과 브라켓 표면은 SEM으로 관찰하였다. 결과의 분석은 t-test를 이용하였으며 결과는 다음과 같다. 1.클로르헥시딘의 법랑질 처리는 전단접착강도에 영향을 미치지 않았다. 2.클로르헥시딘으로 법랑질을 처리한 경우와 그렇지 않는 경우에 브라켓 탈락 양상에 차이가 없었다. 따라서, 클로르헥시딘으로 법랑질을 처리하여도 브라켓 접착에 유해한 작용이 없었고, 따라서 임상사용에 적합하다고 생각된다. The purpose of this study was to determine whether the application of chlorhexidine varnish affects the shear bond strength and failure pattern of orthodontic brackets or not. The experimental group consisted of 22 human premolars which extracted after chlorhexidine vanish application(4 times for 1 week interval) in vivo, and the control group consisted of 22 human premolars which extracted without any pre-treatment. After all teeth were etched with 37% phosphoric acid gel, metal orthodontic brackets (Q-3002, RMO, USA) were bonded to each tooth using auto-polymerizing orthodontic resin (Ortho-One, Bisco, USA) with the same bonding procedure. The shear bond strength was measured with Instron universal testing machine (model 4466, Instron Ltd., England), and the failure pattern of each bracket was examined with Scanning Electron Microscope (SM 840A, JEOL, Japan). The data were analysed statistically with t-test. The results were as follows : 1.Application of chlorhexidine varnish had no significant effect on the shear bond strength of the orthodontic bracket. 2.There was no significant difference in the failure pattern of orthodontic bracket between the experimental group and the control group.

EDP내부통제평가를 위한 전문가시스템의 구축

오원균,김광혁 순천대학교 지역개발연구소 1998 地域開發硏究 Vol.9 No.-

Expert system has been one of the important subjects in accounting information systems research for recent years. There are two considerable reasons in this change. First, the current study should be considered within entire stream to provide a better understanding of its contribution. Second, a discussion of the overall area will provide insights that can be applied to future decision aids derived from new technologies. In this streams, this study constructs an Expert-System for EDP internal control evaluation. The ES was developed with the rule-based ES shell "1st Class". The rules were based on protocol analysis of EDP internal control evaluation provided by an expert having over 10 years of experience in EDP internal control auditing.

작업치료사를 위한 노인우울증 평가도구의 개관

허지원,김환,권혁철 대구대학교 특수교육재활과학연구소 2012 再活科學硏究 Vol.30 No.1

이 연구는 그동안의 연구를 바탕으로 노인의 우울증과 관련하여 작업치료영역에서 노인 우울증환자의 효율적 접근을 위해 평가 도구를 정리하고자 하였다. 관련문헌을 수집한 후 연구자 별로 평가도구를 표로 나열하고 그 중 대표적인 평가도구는 구체적인 특징을 기술하였다. 앞으로 임상가들 및 연구자들은 우울증을 효율적으로 판별하기위하여 평가도구에 대한 충분한 이해를 바탕으로 판별 목적에 알맞으며 타당성이 검증된 도구를 사용할 필요가 있다. The aim of this study was to review the assessment tools of depression in elderly for effective access in the occupational therapy field. Associated literature was reviewed and each researcher listed the assessment tools in a table form and described the characteristics of representative assessment tools. In the future it is important that clinicians and researchers understand the assessment tools fully to differentiate depression effectively and to utilize tools that have proven validity.