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차분 프라이버시를 보장하는 프라이버시 보호 히스토그램 생성 기법
백인철,김종선,정연돈 한국정보과학회 2022 정보과학회논문지 Vol.49 No.6
With the widespread use of data collection and analysis, the need for preserving the privacy of individuals is emerging. Various privacy models have been proposed to guarantee privacy while collecting and analyzing data in a privacy-preserving manner. Among various privacy models, the differential privacy stands as the de facto standard. In this paper, we propose a privacy-preserving histogram construction method guaranteeing differential privacy. The proposed method consists of histogram bin setting and frequency calculation stages. In the first stage, we use the Laplace mechanism to heuristic bin setting algorithms to select a differentially private number of bins. In the second stage, we use the Laplace mechanism to each frequency falling into the bins to output differentially private frequencies. We prove the proposed method guarantees differential privacy and compare the accuracy according to privacy budget values and distribution rates through experiments 데이터 수집과 분석이 활발히 이루어지면서 개인의 프라이버시 보호의 필요성이 대두되고 있다. 프라이버시를 보호하면서 데이터의 수집과 분석을 수행하기 위해 다양한 프라이버시 모델이 제안되었다. 그 중 차분 프라이버시가 사실상의 표준으로 받아들여지고 있다. 본 논문에선 차분 프라이버시를 보장하는 프라이버시 보호 히스토그램 생성 기법을 제안한다. 제안 기법은 히스토그램의 계급 구간 설정 단계와 도수 산출 단계로 구성된다. 첫번째 단계에서는 계급 구간을 결정하는 휴리스틱 알고리즘에 라플라스 메커니즘을 적용하여 차분 프라이버시를 만족하는 계급 구간 개수를 설정한다. 두번째 단계에서는 각 계급 구간에 해당하는 도수에 라플라스 메커니즘을 적용하여 차분 프라이버시를 보장하는 도수를 산출한다. 제안하는 기법이 차분 프라이버시를 보장함을 보이고, 실험을 통해 프라이버시 예산 값의 크기와 분배 비율에 따른 히스토그램의 정확성을 비교한다.
백인철 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.5
In this work, measured data from thickness gauge behind of the finishing mill stand was used for increasing accuracy of thickness control in plate rolling process. The Automatic Gauge Control (AGC) system of the mill could control roll gap for the remaining rolling passes based on the difference between measured and calculated thickness. This work was possible with some modification in software product system to use measured data without additional installation of equipment. As a result, the accuracy of thickness has been increased up to 31%. The accuracy of thickness control was defined as a standard deviation of the differences between target and measured final thickness of average.
소형 지구 관측 위성용 플래시 기반 저장장치 설계 및 시험
백인철,박형식,황기선,Baek, Inchul,Park, Hyoungsic,Hwang, Kiseon 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.5
Recently, small satellite industries are rapidly changing. Demand for high performance small satellites is increasing with the expansion of Earth Observation Satellite market. A next-generation small satellites require a higher resolution image storage capacity than before. However, there is a problem that the HW configuration of the existing small satellite image storage device could not meet these requirements. The conventional data storing system uses SDRAM to store image data taken from satellites. When SDRAM is used in small satellite platform of a next generation, there is a problem that the cost of physical space is eight times higher and satellite price is two times higher than NAND Flash. Using the same satellite hardware configuration for next-generation satellites will increase the satellite volume to meet hardware requirements. Additional cost is required for structural design, environmental testing, and satellite launch due to increasing volume. Therefore, in order to construct a low-cost, high-efficiency system. This paper shows a next-generation solid state recorder unit (SSRU) using MRAM and NAND Flash instead of SDRAM. As a result of this research, next generation small satellite retain a storage size and weight and improves the data storage space by 15 times and the storage speed by 4.5 times compare to conventional design. Also reduced energy consumption by 96% compared to SDRAM based storage devices.
증발기와 응축기 온도변화에 따른R22 대체냉매 R290 및 R1270의 성능평가
백인철,박기정,심윤보,정동수 대한설비공학회 2006 설비공학 논문집 Vol.18 No.10
In this study, performance of 2 pure hydrocarbons R290 and R1270 was measured in an attempt to substitute R22 under 3 different temperature conditions. They were tested in a refrigerating bench tester with a hermetic rotary compressor. The test bench provided about 3.5kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of 7/45℃ and -7/41℃ and -21/28℃ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by 14∼31℃ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.
골반압박벨트가 뭇갈래근과 척추세움근의 근두께에 융합적으로 미치는 영향
백인철,심재훈 한국융합학회 2016 한국융합학회논문지 Vol.7 No.5
본 연구는 초음파 영상(ultrasound imaging)을 이용하여 네발기기 자세(quadruped position)에서 골반압 박벨트(pelvic compression belt)가 뭇갈래근과 척추세움근의 근두께에 융합적으로 미치는 영향을 알아보기 위해 실시되었다. 대상자는 30명의 남자대학생으로 실험에 자발적으로 참여한 자로 선정하였다. 골반압박벨트를 위앞엉덩 뼈가시아래(anterior superior iliac spines)에 착용한 상태와 착용하지 않은 상태에서 네발기기 자세를 실시하였고, 초음파영상 진단장치를 이용하여 근 두께를 측정하였다. 자료분석은 반복측정분산분석을 이용하였다. 연구결과, 뭇 갈래근의 경우 골반압박벨트를 착용하였을 때가 착용하지 않았을 때보다 근두께가 유의하게 증가하였고(p<.05), 척 추세움근의 경우도 골반압박벨트를 착용하였을 때가 착용하지 않았을 때보다 근두께가 유의하게 증가하였다 (p<.05). 따라서 본 연구결과를 통해 골반압박벨트의 착용이 요통환자에게 효과적이며, 임상에서 다양한 네발기기 자세운동의 처방과 적용 시에 유용한 자료로 활용하고자 한다. The purpose of this study was to determine the effectiveness of the pelvic compression belt on the thickness of the erector spinae and multifidus during hip extension on quadruped position. Thirty male university students volunteered to participate in this study. The pelvic compression belt was positioned below the anterior superior iliac spines with the stabilizing pressure using elastic compression bands. Subjects were instructed to perform hip extension in quadruped position with and without applying the pelvic compression belt. The thickness of the erector spinae and multifidus was measured ultrasound during prone position, quadruped position without applying pelvic compression belt and quadruped position applying pelvic compression belt. Data were analyzed using repeated ANOVA. Muscle thickness of multifidus was significantly higher applying the pelvic compression belt than without applying the pelvic compression belt (p<.05). Muscle thickness of elector spinae was significantly higher applying the pelvic compression belt than without applying the pelvic compression belt (p<.05). Therefore, the research can contribute to the prescription and application of quadruped position exercises in clinical practices.