• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.979-985
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• 2011

This paper includes that there are results of designing the flash hider and analyzing fluid dynamics of a front area of the barrel to shorten the length of small arms. Generally, the muzzle flash can be generated out of the barrel by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. Though, the hugh muzzle flash, which is a characteristic of small arms with short barrel length, caused a soldier to aim at the target at night by making the soldier blind for a while and endangers his life by revealing firing position to enemies. Besides, the heat of muzzle flash can weaken the performance of thermal sights, which are attached to small arms for night battlefield. In this paper, flash hiders with several different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length. The performance of each flash hider to reduce the muzzle flash was compared theoretically and experimentally. Through the authorized test procedure, a highly efficient design of flash hider for reducing the muzzle flash was identified. The result of the paper can be helpful when designing flash hiders for small arms with short barrel length.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.5
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• pp.717-724
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• 2010

The initial trajectory of a spheroid configuration bobbin for precision guidance has been investigated by analyzing its aerodynamic load and six-degree-of-freedom motion. The effects of changes in the spheroidal head configuration, flow angle and lateral center-of-gravity offset are numerically studied using the commercial software "FLUENT". A wind tunnel test is also conducted to validate the numerical scheme and to examine effect of the Reynolds number on the flow around the bobbin. It is shown that the size of the separation bubble formed on the surface decreases significantly when the Reynolds number is varied between 110,000 and 140,000. At a zero flow angle, an oblate spheroidal head shows relatively moderate rotation while a prolate spheroidal head shows rapid rotation. The bobbin with a spherical head shape has little effect on the flow direction; however, the oblate bobbin is sensitive to the flow angle. The roll motion of the bobbin is greatly influenced by the lateral center-of-gravity offset and maximum dispersion is observed at half of the radius.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.667-675
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• 2009

Faults can be generated at electric power systems by variety of both certain and uncertain reasons, which may cause harmful effects on electrical apparatuses under operation and stability of electric power system operations, and may also lead to great confusions and inconveniences to individual livings, public works, industrial activities, services, military affairs, etc.. In some cases, intentional inductions of faults are committed for specific purposes, and it is necessary to understand the procedures of fault by some foreign materials. In this paper, compositions and operations of electric power systems, summaries of electrical fault phenomena and fault protection, and restrictions to power system operation were outlined. And the analogies on the procedure of faults from former papers were introduced, and test results that revealed the validity of those analogies were also introduced.

• Journal of Aerospace System Engineering
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• v.5 no.1
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• pp.36-40
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• 2011

In this report US and Korea civil and military simulator certification system is researched, and a plan for improvement is proposed. Korean simulator certification system should adopt FAA's system and improve upon it. Certification criteria should have a basis on FAA certification criteria and add military operation characteristics selectively. Flight test data, used as comparison criteria in certification, should be acquired in package during aircraft development or overseas acquisition. The establishment of certification system is expected to improve external credibility and improve competitiveness in overseas market.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.1
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• pp.35-41
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• 2006

I performed the refraction and binocular test for study of binocular abnormalities. The problems of the accommodation and binocular on subjects was need to the correction of the refractive error. also the subjects was need to a specific treatment for each of the problems. On two patients who had convergence excess, The full corrections of eyeglasses or (+)ADD for near vision were prescribed and the subjects trained for 4 weeks. After 4 weeks, the unconvenience of near vision have more decrease, and the objective test have good results. On clinical, If the optical correction and vision therapy was applied the treatment for binocular abnormalities. The continuous research of vision training in binocular abnormalities will be good results for treatment of several binocular abnormalities in the future.

• Journal of Aerospace System Engineering
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• v.12 no.2
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• pp.30-36
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• 2018

In this study, a small-scaled test system for a tip jet rotor was developed to contribute to the research on unmanned compound rotorcraft. The performance and dynamic characteristics of the tip jet rotor were investigated using the test system. The diameter of the tip jet rotor was set to 2m in consideration of the size of the test site and the pneumatic supply capacity of the. The rotating speed of the rotor was controlled by the pressure of the compressed air. The thrust and forces during the rotor rotation were measured using a load measuring device. A hydraulic actuator was installed for the dynamic test and full-bridge strain gages were attached to the root of each blade to measure the flap, lag, and torsion-wise responses generated when the rotor is excited by the actuator. The performance and dynamic characteristic tests were conducted at various rotor speeds and blade pitches. In order to check the validity of the test results, the results were also compared with the CAMRAD II analysis.

• Journal of the Ergonomics Society of Korea
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• v.16 no.1
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• pp.97-105
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• 1997

An aircraft simulator for ergonomics testing and pilot training was developed from the joint work Agency for Defense Development(ADD) and Daewoo Heavy Industry, LTD, in Korea at first time. It is basically to satisfy the requirements established by FAA-AC-120-40C ( 1995-JAN-26). The aircraft simulator will be used mainly for ergonomics testing and pilot training for basic trainer on ADD and Korea Air Force in near futrue. This simulator reproduces faithfully the cockpit and flight characteristics of the KTX-1 aircraft. It is one of the latest full flight simulators that have the CGI(computer graphic image) visual system and six degree of freedom motions system. Development efforts focused on user-oriented design approach for ergonomics testing and flight training of pilots. Main characteristics of each subsystem are described such as cockpit, instruments, control loading system, motion system, visual system, aural system, instructor operation station and aircraft simulation softwear.

• IE interfaces
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• v.13 no.4
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• pp.688-693
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• 2000

We analyze IS0 9001 audit data and add-on requirements data collected by leader assessors from three leading Korean furniture companies for around three years. We plot a Pareto chart and test the homogeneities for the number of non-compliances and improvement notes across companies. We also fit the data to a loglinear model. Some recommendations with regard to add-on requirements are suggested. The recommendations should be added to IS0 9001 requirements to specifically implement an efficient QMS in Korean furniture industry.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.173-180
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• 2007

In this paper, we have proposed a simple finite element model for separation mode analysis on the roadwheel and track assembly of main battle tank and established a contact stress-based mechanism which could explain the initiation and growth of separation defect occurred during the test of padreplacable track. It was proved that the longitudinal contact shear stress component on the pin hole region of the track shoe body which is parallel to the driving direction is consistent with the crack initiation at the bonding surface between track shoe and wheel-side rubber. The longitudinal shear stress increased locally near the separated region after the separation initiated. So we could assume that the local stress concentration accelerates the separation growth according to the shear mode.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.932-940
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• 2011

This study describes computational simulation results in 2-dimensional and 3-dimensional space concerning large scale gap test(LSGT) by using commercial hydrocode such as AUTODYN and LS-DYNA to analyze the detonation phenomenons of high explosives. To consider the possibilities of LSGT simulation, we used Lee - Tarver reaction rate model of PBX-9404 and Comp-B which were implemented AUTODYN's material library. Also we have tried the diverse numerical schemes such as Lagrangian, Eulerian and ALE(Arbitary Lagrangian Eulerian), SPH(Smoothed Particle Hydrodynamics) in LSGT simulations. After LSGT simulations, we compared the simulation results with published results to verify the LSGT simulations. According to the LSGT simulations, we have concluded as follows. In 2-dimensional and 3-dimensional space, Lagrangian solver provided the most reliable results based on analysis time and accuracy. When using two hydrocodes in 2-dimensional space, the simulation results are almost same except one explosive model. We have verified the modeling method and simulation results of the LSGT by using the commenrcial hydrocode in this study.