• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1384-1392
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• 1999

A high compression rate is required to transmit video sequences over low bit rate networks such as low bit rate communication channels. When highly compressed videos are transmitted over mobile channels of high error rate, bitstreams corrupted by channel errors are not only difficult to be decoded, but also have fatal effects on the other parts of the bitstreams. In this Paper, we propose an error concealment algorithm for recovering the blocks which can not be decoded due to damaged bitstreams. The proposed error concealment algorithm recovers the damaged blocks using the information of adjacent blocks which are correctly decoded. In the proposed algorithm, the motion vector of the damaged block is estimated using the overlapped block motion compensation(OBMC) and block boundary matching(BBM) techniques. Experiment results show that the proposed algorithm exhibits better performance in PSNR than existing error concealment methods.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.1
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• pp.1-12
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• 2004

In this paper, we present an identificable face (n face) detection method robust to color degradation and partial veiling. This method is composed of three parts: segmentation of face candidate regions, extraction of face candidate windows, and decision of veiling. In the segmentation of face candidate regions, face candidate regions are detected by finding skin color regions and facial components such as eyes, a nose and a mouth, which may have degraded colors, from an input image. In the extraction of face candidate windows, face candidate windows which have high potentials of faces are extracted in face candidate regions. In the decision of veiling, using an eigenface method, a face candidate window whose similarity with eigenfaces is maximum is determined and whether facial components of the face candidate window are veiled or not is determined in the similar way. Experimental results show that the proposed method yields better the detection rate by about $11.4\%$ in test DB containing color-degraded faces and veiled ones than a conventional method without considering color degradation and partial veiling.

• Polymer(Korea)
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• v.33 no.5
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• pp.463-468
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• 2009

Syntheses of monodisperse and micron-sized hollow plastic pigment (HPP) were carried out through the core-shell reaction. The effects of the reaction parameters, such as the particle size, molecular weight, the swelling time, agitation rate, and the solid contect were investigated. This micron-sized HPP could be made by using the alkali soluble core with at least bigger than 200 nm size. To obtain a higher opacity ratio, the swelling time and molecular weight of the core should be controlled. The agitation rate affected the particle's morphology. To prevent the shell destruction, the agitation rate must be sufficiently low in case of the syntheses of micron-sized HPP. In this study, micron-sized HPP exhibiting the high hiding power and narrow particle distribution could be obtained.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.110-116
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• 2013

A concrete structure has become bigger and higher because of development of construction technology and a change in construction environment. Also it tends to focus on repairing, reinforcement and exterior in harmony with environment for structure maintenance and performance improvement. The research is about eco friendly durable painting applicable to concrete structure using civil and architecture. it purpose to improve external beauties and durable problems due to flexibility by variation of temperature, adhesion of exterior wall, crack and delamination in existing organic and mineral painting. For those problems, we made a eco friendly pre-paint that is made with preliminary treatment mixture as a highly enriched waterproof agent and adhesive increasing agent in preprocessing mixture. Then we performed an experiment on durability of prevention neutralization of concrete, durability abrasion, hiding power, adhesion, temperature resistance and resistance to chemical attack. The result of an experiment shows that hiding power is over 0.96 in standard test, durability abrasion test got higher value 1mg than water paint 75mg and tensile strength is 6 times higher than standard waterproof specification.

• Journal of Conservation Science
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• v.33 no.6
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• pp.497-506
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• 2017

An investigation on the records of old document was conducted to identify the producing area of white clay and there were on-the-spot surveys to secure raw materials of white clay pigment. Based on the survey results, six raw materials were obtained from the region of Gangwon-do and Gyeongsang-do, South Korea and white clay pigment was subsequently manufactured by applying the hydraulic elutriation method. The results show that the major constituent minerals of YBW, HBW, and MCW were quartz and plagioclase, whereas SGW, HOW, and HGW were composed of clay minerals such as kaolinite and illite. HGW showed the highest $L^*$-value of 92.9. HOW and HGW showed an opacity of 94.1% and 89.6%, respectively, and they had excellent spreadability (270.3 mm and 223.3 mm, respectively). Therefore, HGW, HOW, and SGW have excellent characteristics in terms of color, opacity, and spreadability, and are considered to be highly applicable as white pigments for the Dancheong.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.1010-1021
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• 1999

Camouflage measures in military purpose utilize the apparent temperature difference between target and background, so it is essential to develop a thermal analysis program for apparent temperature predictions and to apply some camouflage measures to real military targets for camouflage purpose. In this study, a thermal analysis program including conduction, convection and radiation is developed and the validity of radiation heat transfer terms is examined. The results show that longwave radiation along with solar radiation should be included in order to predict the apparent temperature as well as the physical temperature precisely. Longwave emissivity variation as an effective camouflage measures is applied to a real M2 tank. From the simulation results, it is found that an effective surface treatment, such as painting of a less emissive material or camouflage clothing, may provide a temperature similarity or a spatial similarity, resulting in an effective camouflage.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.114-120
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• 2006

Bismuth vanadate is one of the environmentally benign substitutes for conventional inorganic pigments composed of heavy metals. The effect of process parameters on the physical properties of bismuth vanadate pigment prepared from aqueous solutions of potassium vanadate and bismuth nitrate were experimentally examined. Two aqueous solutions were fed into precipitation chamber at the same flow rate, and precipitates were formed at primary pH of 4.5 and secondary pH of 7.0~7.5. After aging for 3 hours in reaction mixture, 3 hours' calcination at $400^{\circ}C$ gave bismuth vanadate pigment with a good color and hiding power. Increase in molybdenum concentration in reaction mixture increased the hiding power of the pigment, but the other minor constituents had minor effect on the physical properties of the pigment.

• Journal of the Korea Society for Simulation
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• v.30 no.3
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• pp.11-17
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• 2021

The 30mm anti-aircraft gun has been developed with various types of weapon systems such as protective, protective complex, and wheel-type anti-aircraft artillery. The role of this anti-aircraft gun is an important anti-aircraft weapon in charge of air defense. Anti-aircraft weapons are tasked with defending the airspace from aircraft attacks. In particular, anti-aircraft weapons are organized in combination with mechanized units. And anti-aircraft weapons are prone to attack by enemies because they operate on the front lines of the battlefield. The enemy is expected to attack our troops by covering up or concealing as much as possible in order to increase their viability. Therefore, this study analyzed whether our 30mm anti-aircraft bullets could subdue the enemy in cover. This study analyzed the performance of 30mm anti-aircraft bullets using the M&S technique. For this study, live shooting and simulation method by M&S were used for the experiment. In this study, steel plate and plywood were used for the live shooting experiment. In addition, in the simulation process through M&S, this study used the PRODAS model, AUTODYN model, and Split-x model to analyze the trajectory, penetration, and fragmentation capability of 30mm anti-aircraft bullets. According to the experimental results, it has been proven that 30mm anti-aircraft bullets can destroy enemy armored vehicles. 30mm anti-aircraft bullets succeeded in quickly subduing enemies concealed in general buildings or forests. In this way, it was possible to minimize damage to allies in advance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.229-232
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• 1996

본 논문에서는 공간적 보간을 응용하여 손상된 영상 구획의 데이터를 복원하는 기법을 제시한다. 이러한 기법은 손상된 영상을 부가 정보 없이 복원하는 오류 은폐의 핵심으로 Park[3], Wang[4], Sun[9], Lee[7], Hemami[8] 등에 의해서 여러 가지 기법들이 제안되었다. 그러나 이러한 기법들은 단순히 주변 구획과의 경계면에서의 연속성만을 고려하여 복원하므로 구획 내부의 데이터를 복원하는데 한계가 있으며 계산량도 많은 단점이 있다. 따라서 본 논문에서는 이러한 기존의 기법들의 단점을 극복하기 위하여 Non-Unform Rational B-Spline(NURBS)을 응용한 복원 기법을 제안한다. 제시된 주변 구획의 오류 유무와 윤곽선의 방향에 따라 주변 구획의 화소 정보에 할당되는 가중치를 적절히 변경하여 NURBS를 적용한다. 따라서 윤곽선의 방향을 더욱 견실하게 복원함으로써 주관적, 객관적 관점에서 기존의 기법보다 우수한 영상 구획 복원 성능을 얻을 수 있다. 정지 영상에 대한 컴퓨터 모의 실험 결과 제안하는 알고리듬을 기존의 기법보다 30% 구획 손실율에서 0.5 dB이상 성능 향상을 얻을 수 있음을 관찰하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.793-796
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• 2001

이동 통신 채널과 같이 에러 발생율이 놀은 환경에서 부호화된 비디오 스트림 전송시 발생된 에러는 비디오 화질에 큰 영향을 줄 수 있다. 본 논문에서 현재 널리 사용되고 있는 H.263 복호화기에서 전송도중 에러가 발생했을 경우 추가적인 데이터 삽입 없이 효율적으로 에러를 은닉한 수 있는 기법에 관하여 제안하였다. 특히 인터프레임 영상에서 손상되거나 손실된 움직임벡터에 대해 시간영역에서 관계가 깊은 이전 프레임에서 손실블록(매크로블록)과 같은 위치에 있는 블록의 움직임벡터와 현재 프레임에서 손실블록과 인접한 블록들의 움직임벡터 정보를 이용하여 손상된 블록에 대해 에러를 은폐시키는 방법을 제안한다. 기본적으로 손상된 매크로블록 주변에 인접한 화소값들을 움직임 벡터 추정에 사용한다.