• 한국항해항만학회지
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• 제31권2호
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• pp.159-163
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• 2007

In this paper, we mainly analyze the performance of two ultra wideband communication systems, the classical Time Hopping Binary Pulse Position Modulation (TH-BPPM) UWB system and the Time Hopping Bipolar Pulse Amplitude Modulation (TH-BPAM) UWB system. The performance of TH-BPPM and TH-BPAM is analyzed in detail under an ideal AWGN channel and a correlation receiver. We use the power spectral density function to get the expression of BER of these two UWB systems. It yields simple and exact formulas relating the performance to the system parameters. The analysis shows that TH-BPPM suffers performance degradation with respect to TH-BPAM. Furthermore, we give the computer simulation of both data and image transmission and our simulation results also prove our theoretical analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제29권2호
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• pp.217-224
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• 2005

A new roof edge detection method based on multi level scales of wavelet function is proposed in this paper roof edge and its direction are obtained in this new methods at one time. Besides. scale characteristics of detecting roof edge is analyzed. And a few new methods on fingerprint image pre-processing are described. A method segmenting foreground/background of fingerprint images is proposed, in which Prior estimation of direction field is not required any more. A segmentation method based on multi-scale roof edges is implemented. and the valid scale range of the method is defined. too. And the method is used to segment ridges and valleys in fingerprint images simultaneously The exact direction fields made up of the direction of each point in ridges can be obtained when detecting ridges exactly based on the roof edge detector, in comparison with the traditional coarse estimation of direction fields. Obviously. it will establish a solid foundation for the sequent fingerprint identification.

• 한국정밀공학회지
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• 제14권11호
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• pp.118-125
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• 1997

Non-contacting optical microscopes are increasingly used in recent industrial applications of probes for coordinate measuring machines. They have been found more efficient than conventional touch trigger porbes with ball tips especially in inspecting small-sized objects. There are two major factors affecting measuring accuracy: (1) geometric relations between coordinate systems, (2) magnification ratios of a microscope. In order to determine the magnification ratios exactly, optical imaging of edge was theroretically analyzed and practically adopted to image processing for edge detection. In addition, this paper proposes a geometric calibration method to obtain exact coordinates of measured points from the relations between the machine coordinate system and the image. In the method, the error according to the squareness between the machine axises was also removed. The method was practically adopted to a real coordinate measuring machine. An ultraprecision measurement of 0.2 um uncertainty can be practically achieved.

• Agricultural and Biosystems Engineering
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• 제1권2호
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• pp.95-99
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• 2000

Nondestructive methods such as ultrasonic and magnetic resonance imaging systems have many advantages but still much expensive. And they do not give exact color information and may miss some details. If it is allowed to destruct some biological objects to get interior and exterior informations, constructing 3D image form a series of slices sectional images gives more useful information with relatively low cost. In this paper, a PC based automatic 3D model generator was developed. The system was composed of three modules. The first module was the object handling and image acquisition module, which fed and sliced the object sequentially and maintains the paraffine cool to be in solid state and captures the sectional image consecutively. The second one was the system control and interface module, which controls actuators for feeding, slicing, and image capturing. And the last was the image processing and visualization module, which processed a series of acquired sectional images and generated 3D volumetric model. Handling module was composed of the gripper, which grasped and fed the object and the cutting device, which cuts the object by moving cutting edge forward and backward. sliced sectional images were acquired and saved in a form of bitmap file. 2D sectional image files were segmented from the background paraffine and utilized to generate the 3D model. Once 3-D model was constructed on the computer, user could manipulated it with various transformation methods such as translation, rotation, scaling including arbitrary sectional view.

• Journal of Yeungnam Medical Science
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• 제40권4호
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• pp.394-401
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• 2023

Background: Pregnancy is associated with a number of physical, emotional, and biological changes that can exacerbate maternal psychological disturbances, such as body image concerns and depression. Sleep disturbances during pregnancy can also have adverse impacts. This study aimed to determine the prevalence of depression, sleep disturbances, and body image concerns among pregnant women. The study also examined the relationship between these factors and pregnancy-related variables, such as bad obstetric history and whether the pregnancies were unplanned. Methods: A cross-sectional study of 146 pregnant patients was conducted at a tertiary care center over 15 months. The patients were administered the Beck Depression Inventory, Pittsburgh Sleep Quality Index, and Body Image Concern Inventory questionnaires. Contingency tables, Fisher exact test, and Spearman correlation were used to identify underlying relationships. Results: The prevalence of depression was 22.6%. Although body image disturbance was noted in only 2.7% of patients, 46.6% had poor sleep quality. Poor sleep was associated with primigravida status. Bad obstetric history and unplanned pregnancy were associated with depression. Depression was found to be significantly correlated with body image disturbances and poor sleep quality. Conclusion: Psychiatric disorders were prevalent during pregnancy. This study highlights the importance of screening for depression in pregnant patients. Counselling and caregiver education can be useful for mitigating psychological disturbances. Management of pregnancies by multidisciplinary teams that include psychiatrists could be immensely useful in improving the pregnancy experiences of patients.

• Imaging Science in Dentistry
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• 제54권2호
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• pp.159-169
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• 2024

Purpose: The aim of this study was to evaluate the influence of different cone-beam computed tomography (CBCT) acquisition protocols on reducing the effective radiation dose while maintaining image quality. Materials and Methods: The effective dose emitted by a CBCT device was calculated using thermoluminescent dosimeters placed in a Rando Alderson phantom. Image quality was assessed by 3 experienced evaluators. The relationship between image quality and confidence was evaluated using the Fisher exact test, and the agreement among raters was assessed using the kappa test. Multiple linear regression analysis was performed to investigate whether the technical parameters could predict the effective dose. P-values<0.05 were considered to indicate statistical significance. Results: The optimized protocol (3 mA, 99 kVp, and 450 projection images) demonstrated good image quality and a lower effective dose for radiation-sensitive organs. Image quality and confidence had consistent values for all structures (P<0.05). Multiple linear regression analysis resulted in a statistically significant model. The milliamperage (b=0.504; t=3.406; P=0.027), kilovoltage peak (b=0.589; t=3.979; P=0.016) and number of projection images (b=0.557; t=3.762; P=0.020) were predictors of the effective dose. Conclusion: Optimized CBCT acquisition protocols can significantly reduce the effective radiation dose while maintaining acceptable image quality by adjusting the milliamperage and projection images.

• 한국의류산업학회지
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• 제12권6호
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• pp.843-850
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• 2010

To evaluate the heating performance of commercial heated vests, we investigated the thermal images and the temperature between body and vest for three heated vests. We captured infrared thermography by FT-IR Spectrometer to analyzed the heating temperature of the heating elements taken from the vests, and the maximum heating temperature of the vests was compared with thermal image in the room temperature($18^{\circ}C$). In outdoor experiment($-4.7^{\circ}C$), we measured the inner temperature as well as the thermal image of heated vests. Four healthy men participated in this experiment, and the ANOVA and Duncan test was performed for statistical analysis. As the results, the heating temperature range of the heated vests used in this experiment was $32{\sim}42^{\circ}C$, much lower than the displayed temperature range in their specifications, so the exact specification for heating performance of heated clothing was required. In comparisons of the heating performance among the heated vests, we found out that the insulation of clothing is very important to design the heated clothing, because the inner temperature of the vest had good insulation by itself was higher than that of the vest shown higher temperature over $7^{\circ}$ than another vests at the heating temperature.

• 한국컴퓨터그래픽스학회논문지
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• 제7권1호
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• pp.27-35
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• 2001

3D 컴퓨터 그래픽에서 그림자는 매우 중요한 요소이다. 그림자가 없으면 물체와 물체간의 정확한 위치를 파악하기가 어렵기 때문이다. 즉, 물체가 다른 물체에 바로 붙어있는지 조금 떨어져 있는지를 알아내기가 곤란한 것이다. 이러한 그림자의 중요성에도 불구하고 현존하는 3D 가속 하드웨어들은 그림자의 생성을 전혀 지원하지 못하고 있다. 또한, 이것을 보완하기 위해 많은 그림자 생성 알고리즘들이 제시되었지만 모두 그 한계가 명확하였다. 많은 그림자 생성 기법 중 텍스춰 하드웨어를 이용한 그림자 지도 기법은 광원과 물체가 고정되어 있을 경우 매우 빠른 속도로 그림자를 생성시킬 수 있지만 광원이나 물체가 움직일 경우에는 속도가 느려지게 된다. 본 논문에서는 그림자 지도 기법에 영상기반 렌더링 기법을 적용하여 실시간으로 그림자를 생성하고자 하였다. 본 논문의 기법은 매우 많은 메모리를 필요로 하기 때문에 데이터를 적당히 샘플링하여 웨이블릿 기반 압축 기법으로 압축하였고, 그림자를 생성할 때는 가장 가까이 저장된 그림자들을 2차원 보간하였다.

• 한국실내디자인학회논문집
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• 제27권1호
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• pp.132-139
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• 2018

The high-rise and high-density apartment complexes are built on a large scale and occupy a large portion of the city. The facade of the apartment has a great influence on the cityscape. In particular, the lower part of apartment design gives people to important impressions. For the harmonious landscape of the city, the color plan emphasizes its importance as an influential visual design element that forms the urban landscape. In specialized apartment design, especially finishing material on lower-parts of apartment which is recognized by pedestrian is more important planning factor. Also, finishing material which is one of the primary design elements is important for making the entire image about the building with color. Nowadays stone is mostly used for specialized design on lower-level in apartments. Stone makes luxurious image and harmonious landscape as a nature material. But when planning for design, only general stone graphic or pictures is used without specific plan, after construction, there is a big difference between a plan and the actual color and image. Thus based on exact understanding of stone, I analyzed current state of expression for stone which is used for lower-parts of apartments in Daegu. By this, the purpose of this study is to present detailed data to offer the basis for planning specialized design of lower-parts of apartment.

• 인지과학
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• 제21권1호
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• pp.145-156
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• 2010

본 논문은 원본 디지털 영상을 보호하고 동시에 저작권 정보 등을 저장할 수 있는 콘텐츠 기반 정지 영상 보호에 관한 새로운 방법을 제시한다. Gradient값을 이용한 기존의 알고리즘은 픽셀 단위의 소벨 연산자 알고리즘이 적용되었기 때문에 외부 공격에 대하여 상대적으로 민감하게 반응하고 저작권 정보 등을 정확하게 검출하지 못하는 단점이 있다. 따라서 본 논문에서는 이러한 약점을 보완하기 위하여 블록 단위의 연산이 이루어지는 OCL(Orientation Certainty Level)을 적용하여 특징점을 선택하였다. 실험 결과 기존의 알고리즘에 비해 변화가 심한 공격에서도 99% 이상의 높은 검출도를 나타내는 것을 볼 수 있고 특히 회전 공격에 대해서는 10%이상의 큰 성능 향상을 보여주고 있다.