• YAKHAK HOEJI
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• v.60 no.3
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• Biomedical Science Letters
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• v.17 no.2
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• pp.151-155
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• 2011

Short tandem repeats (STRs) loci are the genetic markers used for forensic human identity test. With multiplex polymerase chain reaction (PCR) assays, STRs are examined and measured PCR product length relative to sequenced allelic ladders. In the repeat region and the flanking region of the commonly-used STR may have DNA sequence variation. A mismatch due to sequence variation in the DNA template may cause allele drop-out (i.e., a "null" or "silent" allele) when it falls within PCR primer binding sites. The STR markers were co-amplified in a single reaction by using commercial PowerPlex$^{(R)}$ 16 system and AmpFlSTR$^{(R)}$ Identifiler$^{(R)}$ PCR amplification kits. Separation of the PCR products and fluorescence detection were performed by ABI PRISM$^{(R)}$ 3100 Genetic Analyzer with capillary electrophoresis. The GeneMapper$^{TM}$ ID software were used for size calling and analysis of STR profiles. Here, this study described a forensic human identity test in which allelic drop-out occurred in the STR system D18S51. During the course of human identity test, two samples with a homozygous (16, 16 and 21, 21) genotype at D18S51 locus were discovered using the PowerPlex$^{(R)}$ 16 system. The loss of alleles was confirmed when the samples were amplified using AmpFlSTR$^{(R)}$ Identifiler$^{(R)}$ PCR amplification kit and resulted in a heterozygous (16, 20 and 20, 21) genotype at this locus each other. This discrepancy results suggest that appropriate measures should be taken for database comparisons and that allele should be further investigated by sequence analysis and be reported to the forensic community.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.178-192
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• 2021

File system forensics typically focus on the contents or timestamps of a file, and it is common to work around file/directory centers. But to recover a deleted file on the disk or use a carving technique to find and connect partial missing content, the evidence must be analyzed using cluster-centered analysis. Forensics tools such as EnCase, TSK, and X-ways, provide a basic ability to get information about disk clusters, but these are not the core functions of the tools. Alternatively, Sysinternals' DiskView tool provides a more intuitive visualization function, which makes it easier to obtain information around disk clusters. In addition, most current tools are for Windows. There are very few forensic analysis tools for MacOS, and furthermore, cluster analysis tools are very rare. In this paper, we developed a tool named FACT (Forensic Analyzer based Cluster Information Tool) for analyzing the state of clusters in a HFS+ file system, for digital forensics. The FACT consists of three features, a Cluster based analysis, B-tree based analysis, and Directory based analysis. The Cluster based analysis is the main feature, and was basically developed for cluster analysis. The FACT tool's cluster visualization feature plays a central role. The FACT tool was programmed in two programming languages, C/C++ and Python. The core part for analyzing the HFS+ filesystem was programmed in C/C++ and the visualization part is implemented using the Python Tkinter library. The features in this study will evolve into key forensics tools for use in MacOS, and by providing additional GUI capabilities can be very important for cluster-centric forensics analysis.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.285.2-286
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• 2003

Analysis of illicit methamphetamine samples seized in Korea is discussed. The samples are extracted with the small portion of ethyl acetate under neutral conditions and the extracts are analyzed by GC-MS. Several impuritiy peaks are found in each chromatrogram. Eight compunds (1,2-Dimethyl-3-phenylaziridine, amphetamine oxime, ephedrine, N-formylmethamphetamine, N-acetylmethamphetamine, acetylephedrine, 3,4-dimethyl-5-phenyl-2-oxazolidone, methamphetamine dimer) are identified impurities in illicit methamphetamine and the identity of the impurity is conformed synthesis. (omitted)

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.306-309
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• 2011

본 연구에서는 정확한 화재원인 분석 및 사기범죄 여부 확인을 위하여 극초단파를 직접 휴대전화에 조사하고, 이때 발생되는 휴대전화의 손상형태를 분석하였다. 극초단파 조사를 위하여 전자레인지를 이용하였으며, 전자레인지의 마그네트론에서 발생되는 2.45 GHz의 극초단파가 휴대전화에 인가될 때 휴대전화의 손상형태를 분석하였다. 실험 결과, 휴대전화에 극초단파를 조사하는 경우, 조사 시간이 길어짐에 따라 심하게 손상되는 경향을 나타내었으며, 특히, 폴더의 힌지 부분 및 인테나 부분과 같이 금속이 설치되는 부분이 심하게 열변형되는 결과를 나타내었다. 휴대전화의 배터리 부분은 외함이 열변형되는 것 이외에 배터리의 손상이나 폭발 등은 발생되지 않는 것으로 평가되었다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.2
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• pp.107-118
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• 2010

This paper proposes a digital forensic method to a file creation transaction using a journal file($LogFile) on NTFS File System. The journal file contains lots of information which can help recovering the file system when system failure happens, so knowledge of the structure is very helpful for a forensic analysis. The structure of the journal file, however, is not officially opened. We find out the journal file structure with analyzing the structure of log records by using reverse engineering. We show the digital forensic procedure extracting information from the log records of a sample file created on a NTFS volume. The related log records are as follows: bitmap and segment allocation information of MFT entry, index entry allocation information, resident value update information($FILE_NAME, $STANDARD_INFORMATION, and INDEX_ALLOCATION attribute etc.).

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.33-36
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• 2022

이벤트 로그(Event Log)는 윈도우 운영체제에서 시스템 로그를 기록하는 형식으로 시스템 운영에 대한 정보를 체계적으로 관리한다. 이벤트는 시스템 자체 또는 사용자의 특정 행위로 인해 발생할 수 있고, 그러한 이벤트 로그는 시스템의 시작과 종료뿐만 아니라 기업 보안 감사, 악성코드 탐지 등 행위의 근거로 사용될 수 있다. 본 논문에서는 PC 종료 관련 실험을 통해 이벤트 로그와 ID를 분석하였다. 분석 결과를 통해 PC의 정상 및 비정상 종료 여부를 판단하여, 현장 압수·수색 시 해당 저장매체에 대해 선별압수·매체압수의 해당 여부 식별이 가능하다. 본 연구는 현장수사관이 디지털증거 압수·수색 시 절차적 적법성과 증거능력 확보의 근거 활용에 기여할 수 있다.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.490-494
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• 2017

With increasing the number of vehicles, the accident rate also goes up and the damaged vehicles should be painted as a final repair process. At the painting stage the solvent-based paint causes environmental problems. To overcome these problems waterborne refinish paint is frequently used recently. However, for waterborne refinish, the costs of insurance coverage are too expensive, and insurance reimbursement costs could be burdensome. Because of the high price of aquatic paint treatment, the service shop might charge the malicious service price. In this study, the surfactant of Surfynol 104, which is the component in the paint, was used as an indicator whether the vehicle was painted with waterborne paint. The specimen was quantitatively analyzed to contain 0.38% of the surfactant through the standard addition method with isotope substituted internal standard (IS) of fluranthene-d10 by curie point pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS).

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.83-97
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• 2023

The purpose of this study was to identify perception of mental health recovery of mentally disordered offenders hospitalized at the national forensic psychiatric hospital. The participants were 91 mentally disordered offenders hospitalized at the national forensic psychiatric hospital in C province. The participants were provided with a written questionnaire about mental health recovery so that they could freely describe it, and collected data were analyzed by two researchers according to Krippendorff's content analysis method. As a result, meaning of mental health recovery were derived from 4 categories and 17 themes, and four categories were 'liberate from psychiatric symptoms', 'stable daily and social life is possible', 'living a hopeful and meaningful life' and 'life without crime after discharge'. mental health recovery facilitators and barriers were derived from 4 categories and 14 themes, 'treatment factors', 'personal factors', 'interpersonal factors' and 'environmental factors'. The results of this study can be used as basic data for education and intervention development for mental health recovery of mentally disordered offenders at the national forensic psychiatric hospital.

• Imaging Science in Dentistry
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• v.54 no.1
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• pp.63-69
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• 2024

Purpose: The objective of this study was to determine the minimum number of teeth in the anterior dental arch that would yield accurate results for individual identification in forensic contexts. Materials and Methods: The study involved the analysis of 28 sets of 3-dimensional (3D) point cloud data, focused on the labial surface of the anterior teeth. These datasets were superimposed within each group in both genuine and imposter pairs. Group A incorporated data from the right to the left central incisor, group B from the right to the left lateral incisor, and group C from the right to the left canine. A comprehensive analysis was conducted, including the evaluation of root mean square error (RMSE) values and the distances resulting from the superimposition of dental arch segments. All analyses were conducted using CloudCompare version 2.12.4 (Telecom ParisTech and R&D, Kyiv, Ukraine). Results: The distances between genuine pairs in groups A, B, and C displayed an average range of 0.153 to 0.184mm. In contrast, distances for imposter pairs ranged from 0.338 to 0.522 mm. RMSE values for genuine pairs showed an average range of 0.166 to 0.177, whereas those for imposter pairs ranged from 0.424 to 0.638. A statistically significant difference was observed between the distances of genuine and imposter pairs(P<0.05). Conclusion: The exceptional performance observed for the labial surfaces of anterior teeth underscores their potential as a dependable criterion for accurate 3D dental identification. This was achieved by assessing a minimum of 4 teeth.