• 한국군사과학기술학회지
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• 제26권5호
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• pp.371-383
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• 2023

Artillery gun tube experiences very high pressure according to the blast of propellant charge. Therfore, it is essential to guarantee the structural safety of the gun tube. On the other hand, weight reduction of gun tube is also a crucial design factor since the agility of artillery vehicle directly leads to its survivability. In this line of thought, this work proposed an efficient design procedure which utilizes the convex combination of breech pressure and projectile base pressure time histories. Its efficiency is verified by comparing with other procedures. Other procedures utilize different computed max pressure rather than the convex combination design pressure. Additionally, a transient analysis is carried out considering the projectile movement and the corresponding pressure distribution through the newly developed ABAQUS user-subroutine. The analysis confirms the structural safety of the lightweight gun tube designed by the proposed method.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권3호
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• pp.121-124
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• 2002

CNTs(Carbon Nano Tube) were employed as an electron source in electron-gun of CRT(Cathode-Ray Tube). The CNTs were grown on the Si substrates and the electron gun by LP-CVD(Low Pressure-Chemical Vapor Deposition). Their physical and field emission property satisfied the requirements of the electron gun of CRT. The fabricated electron gun was inserted into 19 inch-sifted CRT and its operating properly was evaluated for practical usage.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.345-348
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• 2010

Two-stage light-gas gun은 고압실, 압축실 그리고 발사관으로 비교적 간단한 구조로 구성되며, 짧은 시간동안 초고압을 발생시키기 용이함으로 현재까지 고속충격역학, 발사체 공기역학, 재료역학 등 다양한 공학 분야에서 적용되어왔다. 본 연구는 초고압 액체 제트 분사에 적용하기 위한 기초적 연구로서, 고압실 하류에 설치된 제1격막의 파막 압력의 변화에 따른 발사체의 속도 변화 및 관내 압력 거동을 조사하기위하여, 다양한 격막을 적용하여 실험을 수행하였다. 제1격막의 파막 압력은 발사체의 속도에 지배적인 영향을 미치게 되며, 약 14 Bar이상일 경우 발사관의 압력이 압축튜브의 압력보다 크게 증가하였다.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.998-1005
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• 2010

Rifling force has a torsion impulse effect on the gun tube and thus generates undesirable vibration of the gun tube about its bore axis, putting additional stress on the projectile. High rifling force at the muzzle of the gun tube may adversely influence the trajectory of the projectile. And, the service life of rifled gun barrels is known to depend on the rifling force. Rifling force along the path of the projectile in the longitudinal direction of the gun tube can be described with projectile mass, projectile velocity, gas pressure curve and rifling angle. Under the same conditions, the character of the rifling of the gun barrel decisively influences the rifling force curve. To reduce the above mentioned harmful effect, locally distinct maximum of rifling force has to be avoided and maximum rifling force needs to be minimized. The best way to minimize the maximum rifling force is to design a rifling angle function so that the rifling force curve has a near trapezoidal shape. In this paper a new approach to make the optimal rifling force curve is described. The rifling angle determining the rifling force is developed by combined Fourier series and polynomial function to satisfy both the convergence and boundary condition matching problems.

• 대한기계학회논문집A
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• 제41권9호
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• pp.877-885
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• 2017

본 논문에서는 포신의 강선을 고려한 포 발사 해석기법을 다룬다. 포 발사 환경에서 탄두는 고충격 및 고회전의 동적 거동이 발생한다. 이러한 동적 거동에서 탄두 및 탄두 내 전자 장비가 손상되는 사례가 발생하고 있다. 따라서 포 발사 환경에서 탄두의 동적 거동 분석 및 생존성 평가를 위한 포 발사 해석기법의 개발이 필요한 실정이다. 본 논문에서는 앞서 선행연구자들의 단순화된 포 발사 해석기법을 개선하여, 포신의 강선과 탄대의 접촉에 따른 탄두의 회전을 구현할 수 있는 포 발사 해석기법을 개발하였다. 개발된 포 발사 해석기법은 실험결과와 비교를 통하여 검증하였으며, 제안된 해석기법을 이용하여 포 발사 시 탄두의 동적 거동 및 생존성을 평가하였다.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1019-1029
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• 2006

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials, etc, since it can create an extremely high-pressure state in very short time. Of many different types of ballistic ranges developed to date, two-stage light gas gun is being employed most extensively. In the present study, a theoretical work has been made to develop a new type of ballistic range which can easily simulate a flying projectile. The present ballistic range consists of high-pressure tube, piston, pump tube, shock tube and launch tube. The effect of adding a shock tube in between the pump tube and launch tube is investigated. This improvement is identified as the reduction in pressures in the high pressure tube and pump tube while maintaining the projectile velocity. Equations of motions of piston and projectile are solved using Runge-Kutta methods. Dependence of projectile velocity on various design factors such as high pressure tube pressure, piston mass, projectile mass, area ratio of pump tube to launch tube and type of driver gas in the pump tube are also analyzed. Effect of various gas combinations is also investigated. Calculations show that projectile velocities of the order 8 km/sec could be achieved with the present ballistic range.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.4944-4949
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• 2012

이 논문의 목적은 작업장에서 사용하기 위한 에어건의 개발에 관련된 것이다. 에어건은 공작기계를 사용하는 산업현장에서 공작물 칩과 절삭유의 제거를 위한 도구이다. 그리고 그것은 일반적으로 압축공기를 분사하는 용도로 사용된다. 작업자는 에어의 흡입과 분사를 위해 각각의 에어건을 준비하여야 한다. 따라서 우리는 새로운 에어건을 개발하였다. 이 논문에서 우리는 에어건의 설계와 분석을 위한 연구를 한다. 에어건은 몸체, 파이프, 개폐 유닛, 전환 유닛, 에어 튜브 그리고 조립을 위한 요소들로 구성된다. 개발된 에어건은 그 효율을 확인하기 위해 실험된다.

• 한국추진공학회지
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• 제14권4호
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• pp.10-15
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• 2010

Two-stage light-gas gun은 짧은 시간동안 초고압을 발생시키기 용이하므로, 현재까지 고속충격역학, 발사체 공기역학, 재료역학 등 다양한 공학 분야에서 활용되어 왔다. 일반적으로 2단식 경가스총은 고압실, 압축실 그리고 발사관으로 비교적 간단한 구조로 구성되며, 각 부분은 격막에 의해 구분되어있다. 본 연구는 2단식 경가스총을 초고압 액체 제트 분사에 적용하기 위한 기초적 연구로서, 고압실 하류에 설치된 제1격막의 파막 압력의 변화에 따른 발사체의 속도 변화 및 관내 압력 거동을 조사하였다. 그 결과, 제1격막이 파막 되는 압력은 피스톤의 가속에 큰 영향을 미치며, 피스톤이 가속될수록 고압을 생성하는데 용이하였다.

• 한국레이저가공학회지
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• 제8권1호
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• pp.27-37
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• 2005

During laser spot welding of the braun tube electron gun, phenomena such as serious spattering and oxidative reaction, etc. were occurred. The spatter occurred from weld pool affects the braun tube, namely it blocks up a very small hole on the shadow mask and causes short circuit between two poles of the electron gun. We guessed that high power density and oxidative reaction are main sources of these problems. So, we studied to prevent and to reduce spatter occurring in spot welding of the braun tube electron gun using pulsed Nd:YAG laser. The characteristics of laser output power was estimated, and the loss of laser energy by optical parameter and spatter was measured by powermeter. The effects of welding parameters, laser defocused distance and incident angle, were investigated on the shape and penetration depth of the laser welded bead in flare and flange joints. From these results, the laser peak power was a major factor to control penetration depth and to occur spatter. It was found that the losses of laser energy by optic parameter and sticked spatter affect seriously laser weldability of thin sheets.

• Journal of Welding and Joining
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• 제20권4호
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• pp.525-534
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• 2002

During laser spot welding of the braun tube electron gun, phenomena such as serious spattering and oxidative reaction, etc. were occurred. The spatter occurred from weld pool affects the braun tube, namely it blocks up a very small hole on the shadow mask and causes short circuit between two roles of the electron gun. We guessed that high power density and oxidative reaction are main sources of these problems. So, we studied to prevent and to reduce spatter occurring in spot welding of the braun tube electron gun using pulsed Nd:YAG laser. The characteristics of laser output power was estimated, and the loss of laser energy by optical parameter and spatter was measured by powermeter. The effects of welding parameters, laser defocused distance and incident angle, were investigated on the shape and penetration depth of the laser welded bead in flare and flange joints. From these results, the laser peak power was a major factor to control penetration depth and to occur spatter. It was found that the losses of laser energy by optic parameter and sticked spatter affect seriously laser weldability of thin sheets. The deepest penetration depth is gotten on focal position, and a "bead transition" occurred with a slight displacement of focal position relative to the workpiece surface and the absorption rate of the laser energy is affected by the shape factor of the workpiece. When we changed the incident angle of laser beam, the penetration depth was decreased a little with increasing of the incident angle, and the bead width was increased. The spattering was prevented by considering laser beam energy and incident angle.ent angle.