• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.170-176
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• 2018

Recently, weapon system requires personal protection products due to the explosion of rapid-fire explosion, which is considered to be multi threat in modernization, complication and war against terrorism. However, the conventional Korean military bullet protection helmets are not suitable for wearing convenience and combatant interoperability in terms of ergonomic. In this paper, we propose a suitable 3D Scanning method for the head, and compare the measured 3D dimension with the existing 2D measurement value to identity the reliability. Reverse engineered soldier head using the quick surface method was realized with a perfect free-form surface and satisfactory tolerance range (${\pm}0.2mm$). Through the comparison of 3D and 2D measured head dimensions, the absolute error value was 0.73 mm on average and relative error was 0.35 %, confirming the high accuracy of the 3D scan modeling. Also, quick surface method using 3D scanner is suggested a fast and accurate skill for ergonomics in obtaining the head modeling needed for military's personal bullet protection helmet design.

• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.85-94
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• 2009

This paper presents the capability to use QuickBird imagery for effects of forest disturbance in Okgye burned area. Particular attention of this paper deals with the NBR-derived mapping burn severity on QuickBird imagery to locate reliable rehabilitation(namely, secondary succession) over postfire surface. Comparisons of the mapping forest disturbance derived from QuickBird NBR data and the mapping burn severity derived from Landsat ${\Delta}NBR$ data show substantial agreement (KHAT value =0.7886). The method calculated from the correlation between QuickBird wetness and Landsat ETM+ band7 may have application to forest harvest disturbance.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.503-510
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• 2010

The quick variation of the canister wall temperature causes the modification of the shape of canister wall. This paper is the possibility of adoption and the error analysis about the transient heat flux method. The commercial code(Fluent Ver6.2.16) was employed for the calculation of surface temperature in the case of steady and unsteady heat flux condition. Based the surface temperature variation and surface material property, transient heat flux method can calculate the surface heat flux. In the case of steady heat flux condition, the error is about 2%, and in the case of unsteady heat flux condition, the error is about 3.6%. With the unsteady heat flux condition, the time which reach the maximum surface heat flux is almost same between the numerical analysis and transient heat flux method.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.19-30
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• 2000

A finite-volume method is developed to solve turbulent flows around modern commercial hull forms with bow and stern bulbs. The RANS equations are solved. The cell-centered finite-volume method employs QUICK and central difference scheme for convective and diffusive flux discretization, respectively. The SIMPLEC method is adopted for the velocity-pressure coupling. The developed numerical methods are applied to calculate turbulent flow around KRISO 3600TEU container ship. Surface meshes are generated into five blocks: bow and stern bulbs, overhang, fore and afterbody. 3-D field grid system with O-H topology is generated using elliptic grid generation method. Surface friction lines and wake distribution at propeller plane is compared with experiment. The calculated results show that the present method can be used to predict flow around a modern commercial hull forms with bulbs.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.273-274
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• 2010

This study investigated on the early hydration and physical characteristics of blast furnace slag through pH variation. The pH values applied to the experiments were, 12.0 and 13.0 which are the pH values of OPC, and type 3 of pH 14.0 which is a strong alkali condition. A paste and mortar method was used to test blast furnace slag and blast furnace slag containing 2wt% of gypsum. It was found that CAH and CSH phases were formed as key hydrates during the early hydration of blast furnace slag, and ettringites were produced extra during the early hydration of blast furnace slag containing 2wt% of gypsum.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.61-66
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• 1996

The subsequent recrystallizations technique, and experimental strain measurement method by use of recrystallization phenomena, has been successfully applied for the observation of machined surface plastic zones with equivalent plastic strain .epsilon. .geq. 0.5, 0.12 and 0.02 of type 304 stainless steel. The depth of the zone with .epsilon. .geq. 0.5 is very small, 10-15 .mu. m, while those with .epsilon. .geq. 0.12 are 100-200 .mu. m and 200-450 .mu. m, respectively. The depths increase with increasing depth of cut and with decreasing rake angle. The relation between the depth of the zones and the cutting paramenters is shown. The deformation state ahead of the quick-stop cut was also well visualized by the technique.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.271-276
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• 2015

Purpose: Quick freezing is widely used in commercial food storage. Well-known freezing techniques such as individual quick freezing require a low-temperature coolant and small cuts for the heat-transfer efficiency. However, the freezing method for bulk food resembles techniques used in the 1970s. In this study, electromagnetic (EM) heating was applied to improve the quick freezing of bulk food. Methods: During freezing, the surface of food can be rapidly cooled by an outside coolant, but the inner parts of the food cool slowly owing to the latent heat from the phase change. EM waves can directly heat the inner parts of food to prevent it from freezing until the outer parts finish their phase change and are cooled rapidly. The center temperature of garlic cloves was probed with optical thermo sensors while liquid nitrogen (LN) was sprayed. Results: When EM heating was applied, the center cooling time of the garlic cloves from freezing until $-10^{\circ}C$ was 48 s, which was approximately half the value of 85 s obtained without EM heating. For the white radish cubes, the center cooling time was also improved, from 288 to 132 s. The samples frozen by LN spray with EM heating had a closer hardness to the unfrozen samples than the samples frozen by LN only. Conclusions: The EM heating during quick freezing functions to maintain the hardness of fresh food by reducing the freezing time from 0 to $-10^{\circ}C$.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1054-1059
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• 2005

The artificial potential method uses a potential field to guide a robot from a start to a goal configuration respectively. The potential field consists of attractive potential used to pull a robot toward a goal and repulsive potential to keep it away from obstacles. However, there are two problems concerning local minimum and computational cost to be resolved in conventional artificial potential methods. This study proposes a method utilizing a spline surface that interpolates arbitrary boundaries and a domain reduction method that reduces the unnecessary area. The proposed spline surface interpolates arbitrary shaped boundaries and is used as an artificial potential to guide a robot for global motion planning of a mobile robot. A reduced domain process reduces the unnecessary domain. We apply a distance-weighted function as such a function, which blends distances from each boundary with a reduction in computational time compared with other analytical methods. As a result, this paper shows that an arbitrary boundary spline surface provides global planning and a domain reduction method reduces local minimum with quick operation.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.5
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• pp.374-381
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• 2016

The sealing technique is widely used for repairing the cracks on the surface of concrete and preventing their expansion in the future. However, it is difficult to ensure the safety of the workers when sealing large structures in inconvenient working environments. This paper presents the development of a sealing robot system to seal various shapes of concrete surface in rough conditions for a long time. If the robot can maintain the desired contact force, the cracks can be completely sealed. An impedance force tracking controller with slope estimator is proposed to calculate the surface slope in real time using the robot position. It predicts the next point in order to prevent the robot from disengaging from the contact surface owing to quick slope changes. The proposed method has been verified by experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.145-152
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• 1999

This paper presents the principle and experimental results of a non-contact surface roughness measurement by means of screen projected pattern of lase beam reflected from a polished surface. In the reflected laser beam pattern especially from a fine surface like ground or polished one, light intensity varies from the center fo the image to its boundary as the Gaussian distribution. The standard deviation of a light intensity distribution is assumed to be a good non-contact estimator for measuring the surface roughnes, because the light reflectivity is known to be well related with the surface roughness. This method doesn't need to discriminate between the specularly reflected light and the diffusely reflected one, whereas the scattered laser intensity method must do. Nor it needs to adjust the change of light intensity caused by environmental lights or specimen materials. Reflected laser beam pattern narrowly spreads out in the vertical direction to tiny scratches on the polished surface due to abrasives. The deeper the scratch the more the dispersion, which means the rougher surface. The standard deviation of the pattern is nearly in proportion to the surface roughness. Measurement errors by this method are shown to be below 10 percent compared with those obtained by a common contact method. The inclination of measuring unit from the normal axis causes the measurement errors up to 10 percent for an angle of 4 degree. Therefore the proposed method can be used as an on-the-machine quick roughness estimator within 10 percent measurement error.