• 한국농공학회논문집
• /
• 제50권1호
• /
• pp.13-21
• /
• 2008

Water losses in irrigation canals are mainly estimated as the sum of conveyance and delivery water loss. The losses occur via the evaporation, infiltration, gate operation and water distribution processing. Recently, the study regarding these water losses are not satisfactory enough, also delivery water loss has not been mainly considered on field design. The objective of this study is to investigate and analyze the volume of water loss in irrigation canals considering condition of actual farm land. A field measurement was performed at four research sites, which are managed by Korea Rural Community & Agriculture Corporation, to evaluate conveyance and delivery water loss for 2 years. The measurement was performed by canal type, size and designed flow using the inflow-outflow method at a major points such as start and end of each canal, derivation point of canal and inlet of paddy fields. Results of this study showed that water loss ratio in lateral canals was bigger than that of main canal unlike current design standard and the loss decrease as flow increase. The total of water loss ratio including conveyance and delivery water loss in several irrigation canals ranged between 33.25 and 45.0%.

• 한국산학기술학회논문지
• /
• 제9권2호
• /
• pp.270-275
• /
• 2008

자동차용 직선 베벨기어는 대량으로 생산되고 있기 때문에 생산성 향상을 위해 기어가공용 전용기에서 직접 가공하던 것을 냉간 단조 제조방식으로 변경되어 생산되고 있다. 시행착오를 최소화하여 단조에 의한 정확한 최종 형상의 정밀 제품을 조기에 개발하고, 반복 재현성을 확보하는 방법으로 CAD/CAM 시스템의 도입이 필요하다. 본 연구에서는 CAD/CAM 시스템을 활용하여 크라운 치형을 갖는 직선 베벨기어를 모델링 한다. 이를 토대로 NC 데이터 생성과 검증을 통해 가공품을 사전에 예측을 한 후 물림시험의 결과를 통해 마스터 기어를 제작한다. 이러한 마스터기어를 통하여 금형제작이나 가공에 필요한 지그제작을 가능하게 한다.

• Archives of Plastic Surgery
• /
• 제39권3호
• /
• pp.257-260
• /
• 2012

This report describes the use of a tubularized random flap for the curative treatment of recurrent anterior urethral stricture. Under the condition of pendulous lithotomy and suprapubic cystostomy, the urethral stricture was removed via a midline ventral penile incision followed by elevation of the flap and insertion of an 18-Fr catheter. Subcutaneous buried interrupted sutures were used to reapproximate the waterproof tubularized neourethra and to coapt with the neourethra and each stump of the urethra, first proximally and then distally. The defect of the penile shaft was covered by advancement of the surrounding scrotal flap. The indwelling catheter was maintained for 21 days. A 9 month postoperative cystoscopy showed no flap necrosis, no mechanical stricture, and no hair growth on the lumen of the neourethra. The patient showed no voiding discomfort 6 months after the operation. The advantages of this procedure are the lack of need for microsurgery, shortening of admission, the use of only spinal anesthesia (no general anesthesia), and a relatively short operative time. The tubularized unilateral penile fasciocutaneous flap should be considered an option for initial flap urethroplasty as a curative technique.

• 한국레이저가공학회지
• /
• 제12권1호
• /
• pp.19-24
• /
• 2009

Because of its fast and precise welding performance, laser welding is becoming a new excellent welding method. However, the precise focusing and robust seam tracking are required to apply laser welding to the practical fields. In order to laser weld a type of T joint like a circular pipe on a square pipe, which could be met in the three dimensional structure such as an aluminum space frame, a visual sensor system was developed for automation of focusing and seam tracking. The developed sensor system consists of a digital CCD camera, a structured laser, and a vision processor. It is moved and positioned by a 2-axis motorized stage, which is attached to a 6 axis robot manipulator with a laser welding head. After stripe-type structured laser illuminates a target surface, images are captured through the digital CCD camera. From the image, seam error and defocusing error are calculated using image processing algorithms which includes efficient techniques handling continuously changed image patterns. These errors are corrected by the stage off-line during welding or teaching. Laser welding of a circular pipe on a square pipe was successful with the vision tracking system by reducing the path positioning and de focusing errors due to the robot teaching or a geometrical variation of specimens and jig holding.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2007년도 가을 학술발표논문집 Vol.34 No.2 (D)
• /
• pp.127-131
• /
• 2007

전력선을 이용한 통신 기술(Power Line Communication, PLC)은 현재 국내외에서 큰 관심을 받는 연구 분야로 국내에서도 이에 대한 연구와 개발이 활발히 진행되고 있다. 이 기술은 전력선을 이용하여 음성 데이터 인터넷 등을 고속으로 이용할 수 있는 서비스를 제공하여 나아가 가정의 모든 가정기기들을 연결하는 홈 네트워크를 구성할 수도 있다. 하지만 전력선 통신 기술에는 보안상 많은 문제가 존재한다. 그 이유는 전력선 통신 네트워크가 전력선과 IP망을 둘 다 사용하는 혼합형 네트워크로 구성되어 있기 때문이다. 이로 인해 기존 IP망에서 사용하던 보안 기술들을 그대로 전력선 통신 네트워크에 적용하기에는 많은 어려움이 따르며 새로운 기술을 개발하고 그것을 기존 인프라에 적용하는 것 또한 많은 어려움이 따른다. 이에 본 논문에서는 기존 IP망에서 사용하던 공개키와 대칭키 방식을 이용하여 서로 다른 네트워크로 구성되어 있는 전력선 통신 네트워크의 보안을 위한 혼합형 보안구조를 제안한다.

• 한국수소및신에너지학회논문집
• /
• 제13권3호
• /
• pp.197-203
• /
• 2002

The main emphasis of this study was to find an new hydrogen absorbing alloy such as Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties. ($Mg_9Ti_x$)-10, 20wt%Ni-Hx systems were prepared by hydrogen induced mechanical alloying(HIMA) using Mg and Ni chips and sponge Ti. The particles synthesized were characterized by X-ray diffraction, and their morphologies were observed by means of scanning electron microscopy(SEM) with energy dispersive spectrometry (EDS). In addition, the crystal structures were analyzed in terms of their bright-/ dark field images and the selected area diffraction pattern(SADP) of transmission electron microscopy(TEM).

• 대한치과보철학회지
• /
• 제37권1호
• /
• pp.93-103
• /
• 1999

Stress distribution on mandibular implants supporting overdentures were registered in vitro experimental model by means of 4 rosette gauges which were placed around the implant. The overdenture attachments used in this study were the Resilient Dolder bar, Rigid Bolder bar, Round bar, Hader bar & Dal-Ro attachment. An occlusal jig was placed on the overdenture and the loading sites were 3 points which mimicked working, balancing, and median relations. With 5 and 10kg loading, strains were measured by strain indicator(P-3500, Measurement group, Raleigh, USA), and using these data, maximum and minimum principal stresses and Von Mises stress were calculated and evaluated. The results were as follows : There was a tendency of high stress concentration in the lingual side of the implant, and in the buccal side low stress was developed regardless of the attachment systems. The resilient Bolder bar concentrated highest stress among the attachment systems, and the Round bar and the Dal-Ro attachment provided comparatively low stresses around the implant. The rigid Bolder bar concentrated high stress in the mesial side, and the Dal-Ro attachment developed tensile stress patterns in the lingual and distal sides of the implant at the balancing relation.

• 대한치과보철학회지
• /
• 제37권1호
• /
• pp.127-133
• /
• 1999

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the upper first premolar. After 10 metal dies were made fir each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (630N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength(378N). There were no significant differences of the fracture strength by axial inclination in same occlusal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 E
• /
• pp.2259-2261
• /
• 1999

In this paper, an ozonizer, which can generate individual and superposed silent discharge, using three-phase voltage has been designed and manufactured. The ozonizer consists of 3 electrodes(Central Electrode, Internal Electrode and External Electrode) and 2 gaps(gap between Central Electrode and Internal Electrode, gap between Internal Electrode and External Electrode). Ozone is generated according to voltage supplying method to each electrode by individual silent discharge and three-phase superposed discharge. The characteristics of ozone generation were investigated with variation of discharge power and the quantity of supplied gas($O_2$). In case of individual silent discharge, the maximum values of ozone concentration, ozone generation and ozone yield were obtained between internal electrode and external electrode, and its values were 2300[ppm], 570[mg/h] and 745[g/kWh] respectively. Each maximum values was 5039[ppm], 1773[mg/h] and 851[g/kWh] respectively, when three-phase superposed silent discharge was employed. Therefore, characteristics of ozone generation with three-phase voltage are improved compared with single-phase voltage because silent discharge is generated continuously.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 E
• /
• pp.1705-1707
• /
• 1998

In this paper, a superposed discharge type ozonizer was designed and manufactured. The ozonizer is equipped with three electrodes : central electrode, internal electrode and external electrode, and it consists of two gaps. The ozone is generated by superposing silent discharge, which are respectively generated betweens two gaps. This paper describes the following two characteristics : (1) 'the characteristics of discharge with variation with output voltage of AC High Voltage source, quantity of the supplied gas and discharge voltage (2) the characteristics of ozone discharge power, temperature of the supplied gas.