심층 강화학습 기반 자율주행차량의 병합지점 합류 정책 연구

이재휘(Jaehwi Lee),엄찬인(Chanin Eom),이동수(Dongsu Lee),권민혜(Minhae Kwon) 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.11

Themida의 API 난독화 복구 자동화에 관한 연구

이재휘(Jaehwi Lee),이상진(Sangjin Lee) 한국디지털포렌식학회 2017 디지털 포렌식 연구 Vol.11 No.1

프로텍터는 실행파일에 분석방해 기술을 적용해 실행파일 내부 알고리즘을 파악하기 어렵게 만드는 프로그램이다. 프로텍터는 전문지식이 없어도 손쉽게 높은 수준의 분석방해 기술을 적용할 수 있게 해주는 유용한 프로그램이지만, 범죄에 악용되어 범죄행위 입증을 방해하는 경우도 발생한다. 프로텍터가 적용된 실행파일은 높은 수준의 기술을 가진 분석가가 오랜 시간 분석을 진행해야 한다. 만약 프로텍터가 적용된 실행파일이 발견될 때 마다 분석가가 분석방해기술을 우회하는 것은 비효율적이므로, 프로텍터 해제를 자동화 해 분석시간을 단축할 필요가 있다. 본 논문에서는 상용 프로텍터인 Themida 프로텍터가 적용된 실행파일에서 분석방해기술인 API 난독화를 해제하는 자동화 알고리즘을 제안해 프로텍터 해제 작업의 자동화 가능성을 살펴본다. Protector is a program that makes it difficult to understand the algorithm inside the executable file by applying the analysis interruption technique to the executable file. Protector is an useful program that allows you to easily apply high-level analysis interruption techniques without expert knowledge, but it can also be misused to disturb the investigation on the criminal activity. Executables files that applied the protector should be analyzed by a high-level analyst for a long time. It is inefficient to analyze the protected executables everytime, so it is necessary to shorten analysis time by automation. In this paper, we propose an automation algorithm that removes the API wrapping technique in the executable protected by Themida protector.

객체 탐지를 활용한 보행자 밀집 알림 시스템

이재휘(Jaehwi Lee),황태욱(Taeuk Hwang),허병규(Byeonggyu Heo),권민혜(Minhae Kwon) 한국정보과학회 2023 한국정보과학회 학술발표논문집 Vol.2023 No.6

수성미세채널을 형성하는 서방성 매트릭스 장용정을 이용한 탐스로신의 방출제어

이기봉,최성업,전홍렬,이봉상,김현일,이재휘,최영욱 한국약제학회 2004 Journal of Pharmaceutical Investigation Vol.34 No.6

Tamsulosin has been frequently used for the treatment of benign prostatic hyperplasia. To avoid dose-dependent side effects of tamsulosin upon oral administration, the development of sustained-release delivery system is required, that can maintain therapeutic drug levels for a longer period of time. The aim of this study was therefore to formulate sustained-release tamsulosin matrix tablets and assess their formulation variables. We designed enteric coated sustained-release tamsulosin matrices to fulfill above statement. Aqueous microchannels in the enteric film need to be formed in order to obtain tamsulosin release even in an acidic environment such as gastric region. In the sustained-release tamsulosin matrix, low viscosity hydroxypropylmethylcellulose was used as a rate controller. Povidone K30 was also added to the matrices to facilitate water uptake so that a decrease in the release rate of tamsulosin as time elapses was prevented, possibly leading to pseudo zero-order release of the drug. The matrices were enteric-coated with hydroxypropylmethylcellulose phthalate (HPMCP), along with povidone K30 as an aqueous microchannel former. With the aqueous microchannels formed within the enteric film, tamsulosin could be released in an acidic condition. The release of tamsulosin decreased with increasing thickness of HPMCP membrane while the release rates of tamsulosin from those having different HPMCP thickness in pH 7.2 aqueous media were not considerably different, indicating that the enteric film was promptly dissolved at pH 7.2. These results clearly suggest that the sustained-release oral delivery system for tamsulosin could be designed with satisfying drug release profile approved by the KFDA.

현탁된 고형지질나노입자 내로 친수성 약물의 봉입률을 증대시키기 위한 w/o/w 에멀션 가온용융유화법의 평가

이병무,최성업,이재휘,최영욱 한국약제학회 2005 Journal of Pharmaceutical Investigation Vol.35 No.1

Recently increasing attention has been focused on solid lipid nanoparticles (SLN) as a parenteral drug carrier due to its numerous advantages that can come from both polymeric particle and fat emulsions, together with the possibility of controlled release and increasing drug stability. Lipophilic drugs such as paclitaxel. cyclosporin A, and all-trans retinoic acid have been successfully entrapped in SLN but the incorporation of hydrophilic drugs in SLN is very limited because of their very low affinity to the lipid. Therefore, as a new approach to improve the loading of hydrophilic drugs, a w/o/w emulsion technique has been developed. The primary objective of the current study was to improve the loading efficiency of a model hydrophilic drug, glycine (Log P = -3.44) into SLN. The proposed preparation process is as follows: A heated aqueous phase consisting of 0.1 ml of glycine solution in water (100 mg/ml), and poloxamer 188 (5 mg) were then added to a molten oil phase containing precirol (100 mg) and lecithin (5 mg). This mixture was dispersed by sonicator, leading to a w/o emulsion. A double emulsion (w/o/w) was formed after the addition of 2% poloxamer solution to the above dispersed system. After cooling the double emulsion, solid lipid nanosuspensions were successfully formed. The lipid nanoparticles had the mean particle size of 441.25 nm, and the average zeta potential of -20.98 mV. The drug loading efficiency was measured to be 8.54% and the drug loading amount was measured to be 0.92%. The w/o/w emulsion method showed an increased loading efficiency compared to conventional o/w emulsion method.

2×2 교차설계에 의한 생물학적 동등성 시험에서 결측치가 있을 때의 통계적 해석 방법

박상규,이재영,최성업,윤미경,이재휘,최영욱 한국약제학회 2004 Journal of Pharmaceutical Investigation Vol.34 No.5

Statistical interpretations in a bioequivalence trial are considered and studied when the missing observations occurred in 2 × 2 crossover experiment. Patel (1985) suggested the approximate test procedures for carryover effect and drug effect in 2 × 2 crossover design when some of data are missing in the second period. A modified Patel method is newly pro-posed to the bioequivalence trial and it is compared with the current method through the simulation study.

타가메트정 400㎎에 대한 신일시메티딘정 400㎎의 생물학적동등성시험

윤미경,이병무,이성재,김선규,이재휘,최영욱 한국약제학회 2004 Journal of Pharmaceutical Investigation Vol.34 No.6

Cimetidine is a histamine H₂-receptor antagonist, used for the treatment of endoscopically or radiographically comfirmed duodenal ulcer. pathologic GI hypersecretory conditions. and active, benign and gastric ulcer. Simple method for determining cimetidine in human plasma has been developed and validated. The analytical procedure for cimetidine showed a linear relationship in the concentration ranges from 0.05 to 5 pg/ml. Coefficient of variance (CV, ° o) for intraday and interdav validation and relative error (RE. ° o) were less than ±150 o. Based on this analytical method. the bioequivalence of two cimetidine 400 mg tablets, reference (Tagamet 400 mg) and test drug (Sinil CIMETIDINE 400 mg) was evaluated according to the guidelines set by the Korea Food and Drug Administration (KFDA). Release of cimetidine from the tablets in vitro was tested using KP VIII Apparatus II with various dissolution media (pH 1.2. 4.0. 6.8 butter solutions and water). Twenty-four healthy volunteers. 21.38±1.86 years in age and 68.71±8.68 kg in bode weight, were divided into two groups and a randomized 2x2 cross-over study was performed. After oral administration of a tablet containing 400 mg of cimetidine. blood samples were taken at predetermined time intervals and concentrations of cimetidine in plasma were determined using HPLC equipped with UV detector. The dissolution profiles of the two tablet formulations were very similar at all dissolution media. In addition. pharmacokinetic parameters such as AUC, and C_(max) were calculated and ANOVA was employed for the statistical analysis of parameters. The results were revealed that the diterences in AUCf and Cma, between the two tablets were 4.17% and 0.97% respectively. At 90% confidence intervals. the differences in these parameters were also within ± 20° o. All of the above mentioned parameters have met the criteria of KFDA guidelines for bioequivalence, indicating that the test drug tablet (Sinil CIMETIDINE tablet) is bioequivalent to Tagamet 400 mg tablet.

뉴로메드정(옥시라세탐 800㎎)에 대한 뉴라세탐정의 생물학적동등성

최성업,김종석,윤미경,김정일,박석,한상범,이재휘,최영욱 한국약제학회 2004 Journal of Pharmaceutical Investigation Vol.34 No.3

The purpose of the present study was designed to evaluate the bioequivalence of two oxiracetam tablets, Neuromed tablet (Korea Drug Co., reference drug) and Neuracetam tablet (Sam Jin Pharmaceutical Co., test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). Release of oxiracetam from the tablet in vitro was tested using KP Ⅷ Apparatus Ⅱ method with various dissolution media (pH 1.2, 4.0, 6.8 buffer solution and water). Twenty-four healthy volunteers, 23.7 ± 2.4 year in age and 68.9 ± 6.2 ㎏ in body weight, were divided into two groups and a randomized 2×2 cross-over study was performed. After oral administration of a tablet containing 800 ㎎ of oxiracetam, blood samples were taken at predetermined time intervals and concentrations of oxiracetam in plasma were determined using HPLC-MS-MS. The dissolution profiles of two formulations were very similar at all dissolution media. In addition, pharmacokinetic parameters such as AUCt, C_(max) and T_(max) were calculated and ANOVA test was utilized for the statistical analysis of the parameters using logarithmically transformed AUC, and C_(max), untransformed T_(max). The results showed that the differences between two formulations based on the reference drug were 0.42%, 0.45% and -12.58% for AUCt, C_(max) and T_(max), respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals for the log transformed data were within the acceptance range of log 0.8 to log 1.25 (e.g., log0.94 ~ log1.06 and log 0.90 - log 1.07 for AUCt and C_(max), respectively), indicating that Neuracetam tablet is bioequivalent to Neuromed tablet. The major pharmacokinetic parameters, AUCt, and C_(max), met the criteria set by KFDA for bioequivalence indicating that Neuracetam tablet is bioequivalent to Neuromed tablet.