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고차원 자료의 비지도 부분공간 이상치 탐지기법에 대한 요약 연구
안재형,권성훈,Ahn, Jaehyeong,Kwon, Sunghoon 한국통계학회 2021 응용통계연구 Vol.34 No.3
고차원 자료에서 이상치를 탐지하기 위해서는 변수를 선별해야 할 필요성이 있다. 이상치 탐지에 적합한 정보가 종종 일부 변수에만 포함되어 있기 때문이다. 많은 수의 부적합한 변수가 자료에 포함될 경우 모든 관측치의 거리가 비슷해지는 집중효과가 발생하고 이로 인해 모든 관측치의 이상정도가 비슷해지는 문제가 발생하게 된다. 부분공간 이상치 탐지기법은 전체 변수 중 이상치 탐지에 적합한 변수들의 집합을 선별하여 관측치의 이상정도를 측정함으로써 이러한 문제를 극복한다. 본 논문은 대표적인 부분공간 이상치 탐지기법을 부분공간 선정 방식에 따라 세가지 유형으로 분류하고 각 유형에 속한 방법론을 부분공간 선정 기준과 이상 정도 측정 방식에 따라 요약한다. 더하여, 부분공간 이상치 탐지기법들을 적용할 수 있는 컴퓨팅 프로그램을 소개하고 집중효과에 대한 간단한 가상 실험과 자료 분석 결과를 제시한다. Detecting outliers among high-dimensional data encounters a challenging problem of screening the variables since relevant information is often contained in only a few of the variables. Otherwise, when a number of irrelevant variables are included in the data, the distances between all observations tend to become similar which leads to making the degree of outlierness of all observations alike. The subspace outlier detection method overcomes the problem by measuring the degree of outlierness of the observation based on the relevant subsets of the entire variables. In this paper, we survey recent subspace outlier detection techniques, classifying them into three major types according to the subspace selection method. And we summarize the techniques of each type based on how to select the relevant subspaces and how to measure the degree of outlierness. In addition, we introduce some computing tools for implementing the subspace outlier detection techniques and present results from the simulation study and real data analysis.
안재형,김경준,Ahn, Jae-Hyung,Kim, Gyung-Jun 대한한방안이비인후피부과학회 2016 한방안이비인후피부과학회지 Vol.29 No.3
Objectives : Recently, the demands for the effective and safe depigmentating and anti-aging agents of the skin have increased due to the medical, pharmaceutical and cosmetic reasons. The aim of this study is to search new materials from the traditional herbal medicines which inhibit the aging process of skin in vitro.Methods : Human dermis cell (HS68) was used to test the effect of Rhus verniciflua Stokes (RVS). 80% ethanol or water extracts were screened for their inhibitory activities against elastase. Elastase inhibition effect was tested by microplate reader instrument. And MMP-1 suppression effect of RVS was tested by western blot. These cells were investigated the viability by MTS assay. And also the inhibition effect of tyrosinase by RVS was tested.Results : RVS (final concentrstion 1 ㎎/㎖ appeared over 30% of inhibition of elastase activity. So we are investigated anti wrinkle effects of Rhus verniciflua Stokes look through MMP-1 inhibition activity, also Extracts of RVS showed higher anti-tyrosinase activity than arbutin as final concentration 1 mg/ml. These results suggest that herbal medicines could be strong potential sources of inhibition of anti-aging and whitening effects for the skin.Colclusions : RVS was the best suppressor candidate of elastase activity among other control oriental drugs. It was found that RVS did not have toxicity to cells. We found proper concentration of RVS to treat in HS68 culture and investigated not only wrinkle care effect but also whitening effect of RVS.
안재형(Jae-hyoung Ahn),박정흠(Jung-heum Park),이상진(Sang-jin Lee) 한국정보보호학회 2014 정보보호학회논문지 Vol.24 No.5
일반적으로 사용하는 컴퓨터의 저장소는 예상치 못한 오류나 사고로 인해 파일이 삭제되는 일이 발생할 수 있다. 또한 악의적인 목적을 가진 누군가가 안티 포렌식을 목적으로 직접 데이터를 삭제하기도 한다. 이렇게 삭제된 파일이 범죄와 연관된 증거이거나 업무상 중요한 문서인 경우 복구를 위한 대책이 있어야 한다. NTFS, FAT, EXT 와 같은 파일 시스템은 삭제된 파일을 복구하기 위한 기법이 활발히 연구되었고 많은 도구가 개발 되었다. 그러나 최근 NAS 및 CCTV 저장소에 적용된 XFS 파일 시스템을 대상으로는 삭제된 파일을 복구하기 위해 제안된 연구개발 결과가 거의 없으며 현재까지 개발된 도구들은 전통적인 시그니처 탐지 기반 카빙 기법에 의지하고 있어서 복구 성공률이 저조한 상황이기 때문에 이에 대한 연구가 필요하다. 따라서, 본 논문에서는 XFS 파일 시스템에서의 삭제된 파일을 복구하기 위해 메타데이터 기반 복구 방법과 시그니처 탐지 기반 복구 방법을 제안하며 실제 환경에서 실험하여 검증하였다. The files in computer storages can be deleted due to unexpected failures or accidents. Some malicious users often delete data by himself for anti-forensics. If deleted files are associated with crimes or important documents in business, they should be recovered and the recovery tool is necessary. The recovery methods and tools for some filesystems such as NTFS, FAT, and EXT have been developed actively. However, there has not been any researches for recovering deleted files in XFS filesystem applied to NAS or CCTV. In addition, since the current related tools are based on the traditional signature detection methods, they have low recovery rates. Therefore, this paper suggests the recovery methods for deleted files based on metadata and signature detection in XFS filesystem, and verifies the results by conducting experiment in real environment.
안재형(Jae Hyung Ahn) 서강대학교 법학연구소 2011 법과기업연구 Vol.1 No.2
Retransmission battles between broadcast television and multichannel video programming providers(MVPD) including cable television systems and direct-broadcast satellite are taking place frequently. Korean Broadcasting Law clarifies that retransmission of channels not subject to compulsory retransmission(or non-‘must carry’ channels) requires agreement between broadcasters and MPVDs. This article reviews retransmission rules and provisions under Korean Broadcasting Law, how to regulate retransmission battles when the disputes do harm competition of the market, whether retransmission rules are in line with market principle by looking into retransmission battle cases.
임신 34 - 36 주의 조산 : 과연 위험한 것인가 ?
안재형(Jae Hyung Ahn),최형민(Hyung Min Choi),황영수(Young Soo Hwang),홍성훈(Seong Hoon Hong),정병준(Byeong Jun Jung),전명권(Myung Kwon Jeon),이응수(Eung Soo Lee) 대한산부인과학회 2002 Obstetrics & Gynecology Science Vol.45 No.1
N/A Objective : We performed this study to determine the safety and danger of preterm delivery at gestational age 34-36 weeks through antenatal profiles, neonatal conditions, neonatal morbidities. Methods : We reviewed our antenatal and neonatal data between December 1999 and April 2001 to determine the morbidities of infants delivered at gestational age 34-36 weeks using χ2test and Fisher's exact test. Results : 1. Mean age was 30.8±4.58yrs and mean gravida was 2.68±1.56. Preterm premature rupture of membrane was higher in preterm delivery at gestational age 34 and 35weeks(respectively 58.6%, 50%). There was no difference in using tocolytics but, antenatal steroid treatment for prevention of respiratory distress syndrome(RDS) was most frequent in gestational age 34weeks.(20.68%) 2. There was no difference in the risk factor of preterm labor at each group. 3. 1-minute Apgar score<7 was significantly more frequent in neonates at gestational age 34weeks but neonatal weight and meconium staining were not different. 4. The rate of neonatal intensive care unit(NICU) admission was significantly higher in neonates delivered at gestational age 34weeks(93.1%), and RDS occurred in 3 cases delivered at gestational age 34weeks(10.34%). 2 cases delivered at gestational age 34 weeks needed the use of ventilator. Conclusion : Our study shows significant differences in neonatal morbidities between 34weeks and the others. In particular, all cases of Respiratory distress syndrome(n=3) occur in neonates delivered at 34weeks gestation not receiving antenatal steroid treatment and neonatal morbidities at 35 and 36weeks of gestation were not different with full term gestation.