• The Journal of the Korea Contents Association
• /
• v.19 no.11
• /
• pp.383-391
• /
• 2019

This study confirms the mediating effect of learning amotivation in the effect of an elementary school senior parental excessive interference on Internet addiction. To this end, 329 elementary school students in fifth and sixth grade were analyzed by collecting data on parental excessive interference, learning amotivation and Internet addiction. The results of the analysis are as follows. First, there was a significant static relationship between parental excessive interference, learning amotivation, and Internet addiction. Second, parental excessive interference had a significant effect on Internet addiction. Third, parental excessive interference had a significant effect on learning amotivation, and the learning amotivation affected a significant effect on Internet addiction. Through this process, it was confirmed that the learning amotivation has an indirect mediated effect on the effect of parental excessive interference on Internet addiction. Based on the results of this study, the educational implications of preventing Internet addiction among elementary school students and suggestions for follow-up research were discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.370-371
• /
• 2013

현재 운영 중인 DGPS RSIM은 다중 GPS/GNSS 수신기를 이용하여 의사거리 기반 보정정보와 그 무결성 기능을 제공하고 있다. 기준국 시스템 기반 무결성 기능 강화를 위하여, 본 논문에서는 기준국 수신기를 기반으로 전파간섭을 검출할 수 있는 간이 기법과 모니터링 시스템에 대해 다룬다. 기준국 시스템에 전파간섭의 영향을 받게 되었을 경우, 전파간섭 검출을 위한 신규 시스템을 추가하지 않고, 기준 운영 시스템, 즉 기준국 수신기의 실시간 원시정보 출력과 RSIM 메시지의 세부 파라미터 정보를 이용하여 전파간섭을 검출할 수 있는 기법 제안과 그 기법을 적용한 전파간섭 모니터링 시스템을 설계하고, 시뮬레이션 결과를 제시한다. 먼저 DGPS 기준국 시스템의 구성과 기능에 대해 설명하고, 무결성 기능의 한계를 제시한다. 또한 전파간섭이 발생했을 경우 기준국 수신기에 미치는 영향에 대해 분석하고, 분석 결과를 기반으로 기준국에 적용할 만한 간이 전파간섭 검출 기법과 이를 기반으로 한 시스템을 설계하여 그 활용 가능성을 제시한다. 성능평가 결과 제안한 기법 및 시스템이 국제해사기구(IMO)에서 요구하는 무결성 성능 중의 하나인 TTA(Time to Alarm) 10초 이내의 성능을 만족할 수 있음을 제시한다.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2006.05a
• /
• pp.205-210
• /
• 2006

본 논문에서는 간섭계와 직렬 위상 카드를 이용한 광 보안 시스템을 제안하였다. 먼저 원영상을 암호화하기 위해 원영상을 암호화하는 것이 아니라 원영상에 대한 이진 위상 컴퓨터형성홀로그램을 반복 알고리즘을 이용하여 구하고, 이진 위상 컴퓨터형성홀로그램과 무작위 생성된 위상 키 영상과의 XOR 연산을 통해 암호화된 영상을 구한다. 홀로그램의 복호화 과정은 암호화된 영상과 암호화시에 사용된 무작위 위상 영상 키를 직렬 정합시킨 후, 기준파와의 간섭에 의해 수행된다. 이때, 간섭패턴은 주위 환경에 상당히 민감하다. 그래서 광굴절매질의 자기위상공액성질을 이용하여 안정된 간섭패턴을 얻는다. 그리고 원영상은 복원된 홀로그램을 위상 변조한 후, 역푸리에 변환하여 최종적으로 구한다. 제안된 시스템에서는 암호화시에 사용된 무작위 키 영상 정보가 없으면 전혀 복원이 되지 않고, 키 영상을 달리함에 따라 복원되는 홀로그램의 패턴을 달리할 수 있으므로 차별화된 인증 시스템에 활용할 수 있다. 그리고 홀로그램의 성질에 의해 암호화된 영상이 일부 절단되더라도 원래의 영상을 복원할 수 있다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.216-217
• /
• 2003

컴퓨터 기술, 영상 처리기술, 기계장치의 자동화 발전에 따라 레이저를 이용한 형상 측정 기술 개발은 반도체 표면 측정 등에 응용되어지는 매우 중요한 분야를 차지하고 있다. 레이저를 이용한 정밀 표면 측정 기술은 레이저 파장의 1／4에 해당하는 높이까지 CCD 카메라와 연계시켜 측정할 수가 있다. 레이저 간섭계는 Michelson, Mirau, Linnik 등에 의해 개발된 간섭계가 주로 이용되고 있다. 본 논문에서는 4-bucket 알고리즘을 사용하기 위하여 영상을 $\theta$＝$\pi$／2씩 위상 이동시켜 다음과 같은 4개의 간섭 무의 강도 영상 정보를 획득하여 Borland C++ 프로그램을 이용 위상을 계산하였다. (중략)

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.6
• /
• pp.35-41
• /
• 2008

The most important requirement for the automotive radars is the simultaneous target range and velocity measurement under environment of multi-target, clutters, multi-path, and so on. If the many vehicles with 77GHz FMCW(Frequency Modulation Continuous Wave) radar system are in the near area we should consider the interference signals occurred by other radar systems because these signals reduce exact detection of range and velocity. In this paper, we propose the interference cancellation method, which each vehicle radar transmits chirp trains with the different frequency sweep shapes. The proposed method is applied into the various applications such as an intelligent vehicle, Robot, and UGV(Unmanned Ground Vehicle).

• Korean Journal of Optics and Photonics
• /
• v.18 no.5
• /
• pp.295-302
• /
• 2007

This paper presents a rigorous comparison of the design characteristics of polarization-insensitive directional coupler (DC) and multimode interference (MMI) coupler based on rib type waveguides, by using longitudinal modal transmission-line theory (L-MTLT). It shows that the multimode mixing and interference property of MMI can be structurally designed through the continuous evolution of the two-mode coupling property of DC. It also compares and analyzes the coupling efficiency along with the coupling length and the wavelength between polarization-insensitive DC and MMI. From the design properties obtained, it demonstrates for the first time the integration of polarization-insensitive DC or MMI with a Bragg grating and evaluates precisely the filtering characteristics. The numerical results reveal that the DC, as long as it is designed to have the same coupling length for TE and TM modes, has better performance than the MMI in polarization-insensitive filtering behaviour. However, it shows that the MMI with much less coupling length than DC is preferred in the miniaturization of integrated devices.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.1
• /
• pp.29-35
• /
• 2003

In this paper, we propose an improved image decryption system using a phase-encoded image and the principle of interference. An original image and a random image consist of only binary values. The phase-encoded original image is encrypted into a binary phase-only image by multiplying with a phase-encoded random key. Therefore the phase-encoded images have two phase values 0 or $\pi$. The proposed decryption technique is simply performed by interfering between a reference wave and a direct pixel-to-pixel mapping of the encrypted image with a decrypting key. Optical experiments confirmed that the proposed technique is a simple and robust architecture for optical encryption.

• Journal of Korea Society of Industrial Information Systems
• /
• v.12 no.1
• /
• pp.101-107
• /
• 2007

In this paper, we proposed an stable optical security system using interferometer and cascaded phase keys. For the encryption process, a BPCGH(binary phase computer generated hologram) that reconstructs the origial image is designed, using an iterative algorithm and the resulting hologram is regarded as the image to be encrypted. The BPCGH is encrypted through the exclusive-OR operation with the random generated phase key image. For the decryption process, we cascade the encrypted image and phase key image and interfere with reference wave. Then decrypted hologram image is transformed into phase information. Finally, the origianl image is recovered by an inverse Fourier transformation of the phase information. During this process, interference intensity is very sensitive to external vibrations. a stable interference pattern is obtained using self-pumped phase-conjugate minor made of the photorefractive material. In the proposed security system, without a random generated key image, the original image can not be recovered. And we recover another hologram pattern according to the key images, so can be used an authorized system.

• Geophysics and Geophysical Exploration
• /
• v.21 no.2
• /
• pp.94-102
• /
• 2018

To characterize virtual reflection images of deep subsurface by the method of seismic interferometry, we analyzed effects of offset range, ambient noise, missing data, and statics on interferograms. For the analyses, seismic energy was simulated to be generated by a 5 Hz point source at the surface. Vertical components of particle velocity were computed at 201 sensor locations at 100 m depths of 1 km intervals by the finite difference method. Each pair of synthetic seismic traces was cross-correlated to generate stacked reflection section by the conventional processing method. Wide-angle reflection problems in reflection interferometry can be minimized by setting a maximum offset range. Ambient noise, missing data, and statics turn to yield processing noise that spreads out from virtual sources due to stretch mutes during normal moveout corrections. The level of processing noise is most sensitive to amplitude and duration time of ambient noise in stacked sections but also affected by number of missing data and the amount of statics.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.251-254
• /
• 2003

In recent years, shearogrpahy has significantly improved capabilities In the areas of unbend and separation detection in tires. Although shearography has many advantages fur qualitative evaluation, the technique remains the problem of quantitative analysis of inside defects, because shearography needs several effective factors including the amount of shearing, shearine direction and induced load, which exist as barrier for the quantitative analysis of inside defects. Since the factors are highly dependent on inspectors skill and also affect the in-situ workability. The factors were optimized and the size of cracks inside of pipeline and tire has been quantitatively determined.