암호 하드웨어 모듈의 신뢰성 검증 도구

경동욱(Dong Wuk Kyoung),김동규(Dong Kyue Kim) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.1A

암호 시스템들은 복잡한 연산과정을 수행하므로 소프트웨어적으로 구현할 경우 수행속도가 저하되는 단점이 있다. 이를 고속으로 수행하기 위하여 암호 시스템을 하드웨어적으로 구현하는 연구가 활발히 수행되고 있는 것이 현재의 추세이다. 암호 시스템을 하드웨어 모듈로 개발하는 과정 중에는 설계한 모듈이 올바르게 동작하는 지의 여부를 검증하는 과정이 필수적으로 포함된다. 기존의 방법은 검증하고자 하는 암호 알고리즘의 종류에 따라 검증도구를 다시 개발해야 하는 번거로움으로 시간과 비용의 낭비가 초래되었다. 본 논문에서는 기존의 검증 방법을 보완하는 방법으로 PC 기반의 소프트웨어 통제 하에서 어떤 종류의 암호 하드웨어 모듈에 대해서도 호환성을 갖춘 신뢰성 있는 검증 도구를 효과적으로 개발하였다.

면적 효율성을 고려한 AES(Rijndael) 암호시스템의 하드웨어 모듈 설계

경동욱(Dong Wuk Kyoung),김동규(Dong Kyue Kim) 한국멀티미디어학회 2004 한국멀티미디어학회 학술발표논문집 Vol.2004 No.2

정보윤리/점보보호-보안교육 : 감정 자유 기법(EFT : Emotional Freedom Techniques) 활동이 학생의 게임 충동 욕구에 미치는 효과

이경순 ( Kyoung Soon Lee ),남동수 ( Dong Soo Nam ),이태욱 ( Tae Wuk Lee ) 한국컴퓨터교육학회 2012 한국컴퓨터교육학회 학술발표대회논문집 Vol.16 No.1

본 연구는 청소년들의 게임중독을 감소시키기 위하여 ``침을 사용하지 않는 침술``이라는 특성과 ``언제 어디서나 간편하게 행할 수 있다``는 장점을 가지고 있는 감정자유기법(Emotional Freedom Techniques) 활동을 컴퓨터 수업에 적용 시킴으로 서 그 효과를 검증한 실험연구이다. 게임중독 검사를 통해 선발된 학생들을 대상으로 EFT 과정을 익히고 매 수업시간의 도입부분에서 EFT 활동을 컴퓨터 수업에 적용함으로써 게임중독 학생들에게 자기 통제력 향상을 위해 실시한 EFT 활동이 시간과 장소에 제한 없이 게임이용시간 관리능력을 향상시키고 게임에 몰두하는 정도를 완화시켜 게임중독 학생들을 위한 치료의 한 방향을 제시하였고, EFT가 감정을 자유로이 통제하면서 심리적인 안정을 찾는데 교육적 효과가 있음을 시사하는 바이다.

신규 분석기업에 대한 재무분석가의 이익예측특성

고유경(Yoo Kyoung Ko),오광욱(Kwang Wuk Oh),유승원(Seung Weon Yoo),이동헌(Dong Heun Lee),정석우(Seok Woo Jeong) 한국증권학회 2010 한국증권학회지 Vol.39 No.3

본 연구는 2001년부터 2008년까지 Fn-Guide에서 추출된 재무분석가의 17,852개 최초 분석보고서 표본을 기준으로 신규 분석보고서와 계속 분석보고서로 구분한 후, 신규 분석 보고서를 발행하는 재무분석가의 이익예측 특성을 실증 분석하였다. 기존의 연구에서는 재무분석가의 신규 분석 선택유인이 기존의 분석과 다르고, 시장이 이에 대해 차별적으로 반응하고 있음을 발견하였다. 이와 같은 결과를 고려할 때, 신규 분석기업의 이익예측 특성에 대한 연구결과는 시장 참여자들의 반응에 대한 보다 구체적인 원인과 해석을 제공해줄 수 있다. 분석결과, 재무분석가는 기존 분석기업 이익예측치와 비교하여 신규 분석 기업에 대해 상대적으로 덜 낙관적인 예측을 하고 정확한 예측을 하는 것으로 나타났다. 이러한 결과는 시장 최초 표본을 기준으로 한 분석과, 재무분석가 선택 편의를 통제한 이후에도 동일하게 유지되었다. 이는 기존 분석과 비교하여 재무분석가가 신규 분석에 더 많은 시간과 노력을 투입하고 있을 가능성을 의미한다. 또한 신규 분석에 투입되는 노력이 신규 분석의 예측정확성에 부정적으로 영향을 미치는 학습효과 요인 및 정보 접근성의 요인보다 더 중요한 예측특성결정 요인임을 보여준다. 재무분석가의 이익예측치가 신규 분석과 기존 분석이라는 특성에 의해 차별적인 속성을 가진다는 본 연구의 결과는 재무분석가의 종목군의 신규 편입여부가 이익예측치의 특성에 영향을 미치는 요소가 될 수 있음을 보인다. In this study, we examine the forecast properties of newly added firms in the universe of financial analysts using 17,852 firm-year observations provided by Fn-Guide data base from 2001 to 2008. According to prior research, market participants show differential reaction to the analysts` reports of newly added firms in the universe of financial analysts. This suggests that the forecast properties for newly added firms may have their own characteristics and knowledge about the newly added firms forecast properties may be useful not only for potential investors but also for researchers examining financial analysts` roles.

FPGA 상에서 은닉층 뉴런에 최적화된 MLP의 설계 방법

경동욱,정기철,Kyoung Dong-Wuk,Jung Kee-Chul 한국정보처리학회 2006 정보처리학회논문지B Vol.13 No.4

일반적으로 신경망은 비선형성 문제를 해결하기 위해서 소프트웨어로 많이 구현되었지만, 영상처리 및 패턴인식과 같은 실시간 처리가 요구되는 응용에서는 빠른 처리가 가능한 하드웨어로 구현되고 있다. 다양한 종류의 신경망 중에서 다층 신경망(MLP: multi-layer perceptron)의 하드웨어 설계는 빠른 처리속도와 적은 면적 그리고 구현의 용이성으로 고정소수점 연산을 많이 사용하였다. 하지만 고정소수점 연산을 사용하는 하드웨어 설계는 높은 정확도의 부동소수점 연산을 많이 사용하는 소프트웨어 MLP를 쉽게 적용할 수 없는 문제점을 가진다. 본 논문에서는 높은 정확도와 높은 유연성을 가지는 부동소수점 연산을 사용하면서도 은닉층 뉴런수를 주기(cycle)로 빠르게 수행하는 MLP의 완전 파이프라이닝(fully-pipelining) 설계방법을 제안한다. MLP는 주어진 문제에 의해서 자연스럽게 입력층과 출력층의 구조가 결정되지만, 은닉층 구조는 사용자에 의해서 결정된다. 그러므로 제안된 설계방법은 많은 반복수행이 요구되는 영상처리 및 패턴인식 등의 분야에서 은닉층 뉴런수를 최적화 하여 쉽게 성능 향상을 이룰 수 있다. Neural Networks(NNs) are applied for solving a wide variety of nonlinear problems in several areas, such as image processing, pattern recognition etc. Although NN can be simulated by using software, many potential NN applications required real-time processing. Thus they need to be implemented as hardware. The hardware implementation of multi-layer perceptrons(MLPs) in several kind of NNs usually uses a fixed-point arithmetic due to a simple logic operation and a shorter processing time compared to the floating-point arithmetic. However, the fixed-point arithmetic-based MLP has a drawback which is not able to apply the MLP software that use floating-point arithmetic. We propose a design method for MLPs which has the floating-point arithmetic-based fully-pipelining architecture. It has a processing speed that is proportional to the number of the hidden nodes. The number of input and output nodes of MLPs are generally constrained by given problems, but the number of hidden nodes can be optimized by user experiences. Thus our design method is using optimized number of hidden nodes in order to improve the processing speed, especially in field of a repeated processing such as image processing, pattern recognition, etc.

Comparative study on solid self-nanoemulsifying drug delivery and solid dispersion system for enhanced solubility and bioavailability of ezetimibe

( Rehmana Rashid ),( Dong Wuk Kim ),( Abid Mehmood Yousaf ),( Omer Mustapha ),( Fakhar Ud Din ),( Jong Hyuck Park ),( Chul Soon Yong ),( Yu Kyoung Oh ),( Yu Seok Youn ),( Jong Oh Kim ),( Han Gon Choi 영남대학교 약품개발연구소 2016 영남대학교 약품개발연구소 연구업적집 Vol.26 No.-

Background: The objective of this study was to compare the physicochemical characteristics, solubility, dissolution, and oral bioavailability of an ezetimibe-Ioaded solid self-nanoemulsifying drug delivery system (SNEDDS), surface modified solid dispersion (SMSD), and solvent evaporated solid dispersion (SESD) to identify the best drug delivery system with the highest oral bioavailability. Methods: For the liquid SNEDDS formulation, Capryol 90, Cremophor EL, and Tween 80 were selected as the oil, surfactant, and cosurfactant, respectively. The nanoemulsion-forming region was sketched using a pscudotemary phase diagram on the basis of reduced emulsion size. The optimized liquid SNEDDS was converted to solid SNEDDS by spray drying with silicon dioxide. Furthermore, SMSDs were prepared using the spray drying technique with various amounts of hydroxypropylcellulose and Tween 80, optimized on the basis of their drug solubility. The SESD formulation was prepared with the same composition of optimized SMSD. The aqueous solubility, dissolution, physicochemical properties, and pharmacokinetics of all of the formulations were investigated and compared with the drug powder. Results: The drug existed in the crystalline form in SMSD, but was changed into an amor-phous form in SNEDDS and SESD, giving particle sizes of approximately 24, 6, and 11 urn, respectively. All of these formulations significantly improved the aqueous solubility and dis-solution in the order of solid SNEDDS "``: SESD > SMSD, and showed a total higher plasma concentration than did the drug powder. Moreover, SESD gave a higher area under the drug concentration time curve from zero to infinity than did SNEDDS and SMSD, even if they were not significantly different, suggesting more improved oral bioavailability. Conclusion: Among the various formulations tested in this study, the SESD system would be strongly recommended as a drug delivery system for the oral administration of ezetimibe with poor water solubility.

Medicinal Chemistry : Enhanced oral bioavailability of fenofibrate using polymeric nanoparticulated systems: physicochemical characterization and in vivo investigation

( Abid Mehmood Yousaf ),( Dong Wuk Kim ),( Yu Kyoung Oh ),( Chul Soon Yong ),( Jong Oh Kim ),( Han Gon Choi ) 영남대학교 약품개발연구소 2015 영남대학교 약품개발연구소 연구업적집 Vol.25 No.-

Background: The intention of this research was to prepare and compare various solubility-enhancing nanoparticulated systems in order to select a nanoparticulated formulation with the most improved oral bioavailability of poorly water-soluble fenofibrate. Methods: The most appropriate excipients for different nanoparticulated preparations were selected by determining the drug solubility in 1% (w/v) aqueous solutions of each carrier. The polyvinylpyrrolidone (PVP) nanospheres, hydroxypropyl-β-cyclodextrin (HP-β-CD) nanocorpuscles, and gelatin nanocapsules were formulated as fenofibrate/PVP/sodium lauryl sulfate (SLS), fenofibrate/HP-β-CD, and fenofibrate/gelatin at the optimized weight ratios of 2.5:4.5:1, 1:4, and 1:8, respectively. The three solid-state products were achieved using the solventevaporation method through the spray-drying technique. The physicochemical characterization of these nanoparticles was accomplished by powder X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Their physicochemical properties, aqueous solubility, dissolution rate, and pharmacokinetics in rats were investigated in comparison with the drug powder. Results: Among the tested carriers, PVP, HP-β-CD, gelatin, and SLS showed better solubility and were selected as the most appropriate constituents for various nanoparticulated systems. All of the formulations significantly improved the aqueous solubility, dissolution rate, and oral bioavailability of fenofibrate compared to the drug powder. The drug was present in the amorphous form in HP-β-CD nanocorpuscles; however, in other formulations, it existed in the crystalline state with a reduced intensity. The aqueous solubility and dissolution rates of the nanoparticles (after 30 minutes) were not significantly different from one another. Among the nanoparticulated systems tested in this study, the initial dissolution rates (up to 10 minutes) were higher with the PVP nanospheres and HP-β-CD nanocorpuscles; however, neither of them resulted in the highest oral bioavailability. Irrespective of relatively retarded dissolution rate, gelatin nanocapsules showed the highest apparent aqueous solubility and furnished the most improved oral bioavailability of the drug (~5.5-fold), owing to better wetting and diminution in crystallinity. Conclusion: Fenofibrate-loaded gelatin nanocapsules prepared using the solvent-evaporation method through the spray-drying technique could be a potential oral pharmaceutical product for administering the poorly water-soluble fenofibrate with an enhanced bioavailability.

Enhanced oral bioavailability of fenofibrate using polymeric nanoparticulated systems: physicochemical characterization and in vivo investigation

Yousaf, Abid Mehmood,Kim, Dong Wuk,Oh, Yu-Kyoung,Yong, Chul Soon,Kim, Jong Oh,Choi, Han-Gon Dove Medical Press 2015 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.10 No.-

<P><B>Background</B></P><P>The intention of this research was to prepare and compare various solubility-enhancing nanoparticulated systems in order to select a nanoparticulated formulation with the most improved oral bioavailability of poorly water-soluble fenofibrate.</P><P><B>Methods</B></P><P>The most appropriate excipients for different nanoparticulated preparations were selected by determining the drug solubility in 1% (w/v) aqueous solutions of each carrier. The polyvinylpyrrolidone (PVP) nanospheres, hydroxypropyl-β-cyclodextrin (HP-β-CD) nanocorpuscles, and gelatin nanocapsules were formulated as fenofibrate/PVP/sodium lauryl sulfate (SLS), fenofibrate/HP-β-CD, and fenofibrate/gelatin at the optimized weight ratios of 2.5:4.5:1, 1:4, and 1:8, respectively. The three solid-state products were achieved using the solvent-evaporation method through the spray-drying technique. The physicochemical characterization of these nanoparticles was accomplished by powder X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Their physicochemical properties, aqueous solubility, dissolution rate, and pharmacokinetics in rats were investigated in comparison with the drug powder.</P><P><B>Results</B></P><P>Among the tested carriers, PVP, HP-β-CD, gelatin, and SLS showed better solubility and were selected as the most appropriate constituents for various nanoparticulated systems. All of the formulations significantly improved the aqueous solubility, dissolution rate, and oral bioavailability of fenofibrate compared to the drug powder. The drug was present in the amorphous form in HP-β-CD nanocorpuscles; however, in other formulations, it existed in the crystalline state with a reduced intensity. The aqueous solubility and dissolution rates of the nanoparticles (after 30 minutes) were not significantly different from one another. Among the nanoparticulated systems tested in this study, the initial dissolution rates (up to 10 minutes) were higher with the PVP nanospheres and HP-β-CD nanocorpuscles; however, neither of them resulted in the highest oral bioavailability. Irrespective of relatively retarded dissolution rate, gelatin nanocapsules showed the highest apparent aqueous solubility and furnished the most improved oral bioavailability of the drug (~5.5-fold), owing to better wetting and diminution in crystallinity.</P><P><B>Conclusion</B></P><P>Fenofibrate-loaded gelatin nanocapsules prepared using the solvent-evaporation method through the spray-drying technique could be a potential oral pharmaceutical product for administering the poorly water-soluble fenofibrate with an enhanced bioavailability.</P>

The Effect of Body Mass Index on Intra-Abdominal Pressure and Blood Loss in Lumbar Spine Surgery

Han, In-Ho,Son, Dong-Wuk,Nam, Kyoung-Hyup,Choi, Byung-Kwan,Song, Geun-Sung The Korean Neurosurgical Society 2012 Journal of Korean neurosurgical society Vol.51 No.2

Objective : The purpose of this prospective study was to evaluate the effects of body mass index (BMI) on intra-abdominal pressure (IAP) and intraoperative blood loss (IBL) during lumbar spinal surgery. Methods : Thirty patients scheduled for single level posterior lumbar interbody fusion were allocated equally to a normal group (Group 1, BMI;$18.5-22.9kg/m^2$), an overweight group (Group 2, BMI; $23-24.9kg/m^2$), and an obese group (Group 3, BMI; $25.0-29.9kg/m^2$) according to BMI. IAP was measured using a urinary bladder catheter; 1) supine after anesthesia induction, 2) prone at skin incision, 3) prone at the end of surgery. In addition, IBL was also measured in the three groups. Results : IAP in the supine position was not significantly different in groups 1, 2, and 3 (2.7 mm Hg, 3.0 mm Hg, and 4.2 mm Hg, respectively) ($p$=0.258), and IAP in the prone position at incision increased to 7.8 mm Hg, 8.2 mm Hg, and 10.4 mm Hg, respectively, in the three groups, and these intergroup differences were significant, especially for Group 3 ($p$=0.000). IAP at the end of surgery was slightly lower (7.0 mm Hg, 7.7 mm Hg, and 9.2 mm Hg, respectively). IBLs were not significantly different between the three groups. However, IBLs were found to increase with IAP in the prone position ($p$=0.022) and BMI ($p$<0.05). Conclusion : These results show that BMI affects IAP in the prone position more than in the supine position during lumbar spinal surgery. In addition, IBLs were found to increase with IAP in the prone position and with BMI. Thus, IBLs can be expected to be higher in morbidly obese patients due to an increased IAP.

포즈 인식에서 효율적 특징 추출을 위한 3차원 데이터의 차원 축소

경동욱,이윤리,정기철,Kyoung, Dong-Wuk,Lee, Yun-Li,Jung, Kee-Chul 한국정보처리학회 2008 정보처리학회논문지B Vol.15 No.5

사용자 포즈의 3차원 데이터 생성을 통한 3차원 포즈 인식은 2차원 포즈 인식의 문제점을 해결하기 위해서 많이 연구되고 있지만, 3차원 표면 데이터의 방대한 양으로 포즈 인식에서 중요한 특징 추출(feature extraction)이 어렵고 수행 시간이 많이 걸리는 문제점을 가지고 있다. 본 논문에서는 3차원 포즈 인식의 두 가지 문제점인 특징 추출의 어려움과 느린 처리속도를 개선하기 위해서 3차원 형상복원 기술로 모델의 3차원 표면 점들로 구성된 데이터를 2차원 데이터로 변환하는 차원 축소(dimension reduction) 방법을 제안한다. 실린더형 외곽점을 이용한 메쉬없는 매개변수화(meshless parameterization) 방법은 방대한 데이터인 3차원 포즈 데이터를 2차원 데이터로 변환하여 특징 추출과 매칭과정의 연산 속도를 향상 시키며, 특징 추출의 효율성 검증을 위해 간단한 환경에서 실험이 가능한 손 포즈 인식 및 인간 포즈 인식에 적용하였다. 3D posture recognition is a solution to overcome the limitation of 2D posture recognition. There are many researches carried out for 3D posture recognition using 3D data. The 3D data consist of massive surface points which are rich of information. However, it is difficult to extract the important features for posture recognition purpose. Meanwhile, it also consumes lots of processing time. In this paper, we introduced a dimension reduction method that transform 3D surface points of an object to 2D data representation in order to overcome the issues of feature extraction and time complexity of 3D posture recognition. For a better feature extraction and matching process, a cylindrical boundary is introduced in meshless parameterization, its offer a fast processing speed of dimension reduction process and the output result is applicable for recognition purpose. The proposed approach is applied to hand and human posture recognition in order to verify the efficiency of the feature extraction.