• 전자공학회논문지CI
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• 제45권4호
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• pp.1-11
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• 2008

본 논문에서는 adaboost(adaptive boosting)를 이용한 눈 검출 알고리즘을 제안한다. 또한 기존의 adaboost를 이용한 눈 검출 알고리즘의 문제점으로 지적된, 실제 눈이 아님에도 불구하고, 눈으로 찾는 오검출율(false alarm rate)를 감소시키기 위해 각막 면에 생성되는 조명의 반사광을 모델링을 통해 추정하고 adaboost의 학습과 눈 검출에 사용되는 박스의 최적의 크기를 실험을 통해 결정하였다. 위의 결과로 검출된 눈 영역을 중심으로 일정 영역에 대하여 동공과 홍채 영역을 원형검출기(circular edge detector)를 이용하여 검출하였다. 실험결과 휴대폰으로 취득한 얼굴영상에서 약 99%의 눈 검출 정확도를 나타내었으며 휴대폰 환경에 적용했을 때 처리시간은 1초 내외 소요됨을 알 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.159-165
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• 2003

뇌자도 측정을 위해 고감도 superconducting quantum interference device (SQUID) 자력계 및 37채널 뇌자도 측정장치를 제작하고 동작특성을 조사하였다. 자속-전압 변환계수 및 변조전압 진폭이 큰 double relaxation oscillation SQUID (DROS)를 사용함으로서 구동회로를 간단히 하였고 안정한 SQUID 동작을 실현할 수 있었다. DROS 자력계를 설계 및 제작한 결과 자력계의 평균 백색잡음은 약 3 fT/√Hz으로서 우수한 자장감도를 가짐을 확인하였다 머리의 평균곡률을 기반으로 37개의 자력계를 반구형으로 배치시켰으며, 외부잡음을 줄이기 위해 신호채널 외에 11개의 기준채널을 설치하여 소프트웨어 방법으로 합성미분계 및 적응필터링을 형성할 수 있도록 하였다 저잡음 듀아를 제작하여 동작특성을 측정한 결과 듀아 열자기 잡음이 자력계 잡음에 비해 무시할 수 있는 수준이었으며, 듀아의 용량은 30 L, 액체헬륨 증발율은 4 L/d이다. 제작된 시스템을 이용하여 청각유발 신호를 측정하고, 디지털 신호처리 및 전류원 국지화 프로그램을 구성하여 전류원의 위치를 추정함으로서 개발된 시스템을 뇌자도 측정에 활용하였다.

• 한국컴퓨터정보학회논문지
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• 제27권8호
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• pp.85-90
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• 2022

본 연구는 실제 카메라의 움직임과 동일한 가상 카메라의 움직임을 구현하기 위해 전통적인 모션그래픽 제작 방법이 가지고 있는 소요시간과 비용에 대한 단점을 줄이기 위해 AR Core 기반의 모바일 디바이스 실시간 트래킹 데이터를 이용하여 모션그래픽 가상카메라를 생성하는 방법을 제안했다. 제안하는 방법은 촬영 이후 저장된 비디오 파일에서의 트래킹 작업을 간소화하고, 촬영 단계에서 트래킹 성공 유무를 판단하기 위해 AR Core 기반 모바일 디바이스에서 촬영과 동시에 진행하는 방법이다. 실험결과 전통적인 방법과 비교하였을 때 모션그래픽 결과 이미지의 차이는 없었으나 300프레임(frame) 영상 기준 6분 10초의 시간이 소모된 반면에 제안한 방법은 이 단계를 생략할 수 있어 매우 높은 시간적 효율성을 갖는다. 현재 가상 증강 현실을 이용한 영상제작에 대한 관심과 다양한 연구가 진행되고 있는 시점에서 본 연구는 가상 카메라 생성과 매치 무빙 등에서 활용될 있을 것이다.

• Molecules and Cells
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• 제38권6호
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• pp.482-495
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• 2015

Sphingolipids such as ceramide, sphingosine-1-phosphate and sphingomyelin have been emerging as bioactive lipids since ceramide was reported to play a role in human leukemia HL-60 cell differentiation and death. Recently, it is well-known that ceramide acts as an inducer of cell death, that sphingomyelin works as a regulator for microdomain function of the cell membrane, and that sphingosine-1-phosphate plays a role in cell survival/proliferation. The lipids are metabolized by the specific enzymes, and each metabolite could be again returned to the original form by the reverse action of the different enzyme or after a long journey of many metabolizing/synthesizing pathways. In addition, the metabolites may serve as reciprocal biomodulators like the rheostat between ceramide and sphingosine-1-phosphate. Therefore, the change of lipid amount in the cells, the subcellular localization and the downstream signal in a specific subcellular organelle should be clarified to understand the pathobiological significance of sphingolipids when extracellular stimulation induces a diverse of cell functions such as cell death, proliferation and migration. In this review, we focus on how sphingolipids and their metabolizing enzymes cooperatively exert their function in proliferation, migration, autophagy and death of hematopoetic cells, and discuss the way developing a novel therapeutic device through the regulation of sphingolipids for effectively inhibiting cell proliferation and inducing cell death in hematological malignancies such as leukemia, malignant lymphoma and multiple myeloma.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.33-37
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• 2003

Endovaginal and endorectal receiver only surface coil were designed for MR imaging(MRI) and $^1H$ MR spectroscopy(MRS) for the uterine cervix and the prostate. The shape of endovaginal coil wire was rectangular with round comer. The shape of endorectal coil wire was long elliptic shape during insertion and circular shape after insertion. Conventional spin echo and fast spin echo sequences were used as T1 and T2 weighted imaging sequences, respectively. 3D volume localized in vivo $^1H$ MR spectroscopy of the human cervix and prostate was performed using PRESS or STEAM localization method. Using home-built endvaginal and endorectal coils, excellent T1 and T2 images were obtained to visualize early cervical and prostate tumors. 3D volume localized in vivo $^1H$ MRS was useful to differentiate the cancerous tissue from the normal tissue.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.898-904
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• 2010

Unmanned autonomous forklifts have a great potential to enhance the productivity of material handling in various applications because these forklifts can pick up and deliver loads without an operator and any fixed guide. There are, however, many technical difficulties in developing such forklifts including localization, map building, sensor fusion, control and so on. Implementation, which is often neglected, is one of practical issues in developing such an autonomous device. This is because the system requires numerous sensors, actuators, and controllers that need to be connected with each other, and the number of connections grows very rapidly as the number of devices grows. Another requirement on the integration is that the system should allow changes in the system design so that modification and addition of system components can be accommodated without too much effort. This paper presents a network-based distributed approach where system components are connected to a shared CAN network, and control functions are divided into small tasks that are distributed over a number of microcontrollers with a limited computing capacity. This approach is successfully applied to develop an unmanned forklift.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권3호
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• pp.148-155
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• 2017

본 논문에서는 스마트폰 내 가속도, 자기장, 자이로스코프 센서들을 이용해 사용자의 걸음과 걸음 수를 인식하는 시스템을 개발하였다. 센서 데이터 분석을 통해 사용자의 걸음을 스마트폰을 손에 든 상황과 주머니에 넣은 상황에서의 걸음 패턴으로 분류하고 이를 추출할 수 있는 알고리즘을 사용하여 걸음 수 인식의 정확성을 개선하였다. 알고리즘을 적용한 결과 손에든 상황에서 96%, 주머니에 넣은 상황에서 95.5% 수준의 걸음 수 인식 정확도를 보였으며, 나머지 터치 스크린, 위아래 반복 흔들기, 앉아서 일어서기, 오른쪽 왼쪽 흔들기와 같은 행위로 인해 발생하는 6%의 오차를 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.151-156
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• 2020

A technology for calculating the position of a device is very important for users who receive positioning services, regardless of various indoor/outdoor or with/without any positioning infrastructure existence environments. One of the positioning resources widely used at present, LTE, is a typical infrastructure that can overcome the space limitation, however its positioning method based on the position of the LTE base station has low accuracy. A method of constructing a radio wave map of an LTE signal has been proposed as a method for overcoming the accuracy, but it takes a lot of time and cost to perform high-density collection in a wide area. In this paper, we describe a method of creating a high-density DB for the entire region by using vehicle-based partial collection data. To create a positioning database, we applied the idea of Generative Adversarial Network (GAN), which has recently been in the spotlight in the field of deep learning, and learned the collected data. Then, a virtually generated map which having the smallest error from the actual data is selected as the optimum DB. We verified the effectiveness of the positioning DB generation algorithm using the positioning data obtained from un-collected area.

• International journal of advanced smart convergence
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• 제6권1호
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• pp.26-31
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• 2017

When mobile navigator device accesses data randomly, the cache memory performance is rapidly deteriorated due to low memory access locality. For instance, GPS (General Positioning System) of navigator program for automobiles or drones, that are currently in common use, uses data from 32 satellites and computes current position of a receiver. This computation of positioning is the major part of GPS which accounts more than 50% computation in the program. In this computation task, the satellite signals are received in real time and stored in buffer memories. At this task, since necessary data cannot be sequentially stored, the data is read and used at random. This data accessing patterns are generated randomly, thus, memory system performance is worse by low data locality. As a result, it is difficult to process data in real time due to low data localization. Improving the low memory access locality inherited on the algorithms of conventional communication applications requires a certain optimization technique to solve this problem. In this study, we try to do optimizations with data and memory to improve the locality problem. In experiment, we show that our case study can improve processing speed of core computation and improve our overall system performance by 14%.

• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.196-201
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• 2011

Near-field properties of light emanated from a subwavelength double slit of finite length in a thin metal film, which is essential for understanding fundamental physical mechanisms for near-field optical beam manipulations and various potential nanophotonic device applications, is investigated by using a three-dimensional finite-difference time-domain method. Near-field intensity distribution along the propagation direction of light after passing through the slit has been obtained from the phase relation of transverse electric and magnetic fields and the wave impedance. It is found that the near field of emerged light from the both slits is evanescent, that is consistent with conventional surface plasmon localization near the metal surface. Due to the finite of the slit, the amplitude of this evanescent field does not monotonically approach to than of the infinite slit as the slit length increases, i.e. the near-field of the longer slit along the center line can be weaker than that of the shorter one.