Earticle

New psychoactive substances(NPS) are a novel synthetic substance designed for abuse while evading the law. In terms of synthetic cannabinoids, the most common form found in Korea is a group of JWH-018 and its variations. Since the first appearance of synthetic cannabinoids in 2009, their use has been increasing in Korea. In this study, we report on the trend of NPS in Korea from 2009 to present. In summary, the number of detected cases of NPS is gradually increased with time, from 8 cases in 2009 to 143 cases in 2016. Though a sudden decrease was found to 58 cases in 2018, they increased by 317 % in the following year. Many NPS-related research papers have been published since 2012, and recently we developed a simultaneous detection method for total 59 synthetic cannabinoids in human hair using LC-MS/MS. In the case studies based on the analytical results of drug abusers’ hair, UR-144 was frequently abused in 2014, while AB-CHMINACA was the most abused drug during 2016∼2017. From 2014 to present, most frequently detected synthetic cannabinoids were AB-CHMINACA, 43 cases in total, followed by 5F-ADB(25 cases), JWH-210(20 cases), UR-144(11 cases) and 5F-MDMB-PICA (8 cases) in order. The diversity of synthetic cannabinoids and the speed of their emergence are noticeable differences compared to those of traditional drugs. Particularly, three new types of synthetic cannabinoids(5F-MDMB-PICA, AMB-FUBINACA and 4F-MDMB-BUTINACA) were introduced in Korea in 2020, and more than two types of these drugs were abused in a mixed form.

Seized pink capsule containing white powder was extracted with methanol using ultra-sonication method. Gas chromatography-Mass spectrometry(GC-MS) was used for identification of this sample, and putative 2-aminopropyl-2,3- dihydrobenzofuran(APDB) and caffeine were detected. APDBs is a central nervous system(CNS) stimulant classified as phenethylamines. It is an analogue of 3,4-methylenedioxyamphetamine(MDA) where the heterocyclic 4-position oxygen from the 3,4-methylenedioxy ring has been replaced with a methylene bridge. To elucidate exact chemical structures of target compound, the methanol extract was isolated with preparative high performance liquid chromatography(HPLC) to separate the target compound from caffeine. Then, target compound was analyzed with one-dimensional(1D-) and two-dimensional(2D)-nuclear magnetic resonance(NMR). The 1H-NMR spectra presented 15 proton signals and the 13C-NMR spectra exhibited 11 carbon signals. All the protons and carbons were assigned by their couplings and correlations observed in 1H-13C Hetero nuclear Multiple Bond Correlation(HMBC) and 1H-13C Hetero nuclear Single Quantum Coherence(HSQC) spectra. From all of analysis data, target compound was identified as 6-APDB and 6-APDB was first founded in our country.

Evidence contamination may occur due to human or environmental factors during the process of collecting evidence at the crime scene or analyzing it in a laboratory. At this time, the detection of contaminated DNA profile may lead to wrong decision of the investigation direction and have an unnecessary effect on the case, resulting in waste of manpower and time. In order to prevent such analysis errors, the establishment of the DNA database of the investigators and analysts for the purpose of exclusion is an important factor for improving the quality of analysis. In this study, we analyzed the status of the elimination DNA database to date, the number of matched investigation personnels by year, and the characteristics according to the type of evidence. We also reviewed possible routes of contamination and plans to improve the quality of the DNA examination. Since the DNA examination began in 1992, and until December 2020, 3,276 investigators, 611 analysts, and 34 coroner, a total of 3,921 were uploaded onto the DNA database. Various methods have been proposed to prevent contamination of evidence, including frequent replacement of gloves, masks, and lab coats, restriction of access to the location of the crime scene and the laboratory, periodic cleaning and prevention of contamination of the test area and equipment. Furthermore, it is necessary for investigation personnels to continuously recognize the contamination routes.

Breath alcohol test is the most frequently used technique to determine drivers with alcohol impairment with an ease of measurement at the roadside using a screening device, called breathalyzer. However, the drawbacks of breathalyzer is the interference resulted from the use of a mouthwash and the alcohol remained in the oral cavity right after the alcohol consumption. In order to determine the factors that affect the false positive results, the breath alcohol concentration was measured over time using 4 alcohol solutions(2 types of alcoholic beverages and 2 types of mouthwashes) with 5 Korean male adults. The results showed that the remaining time of ethanol in mouth was longer with the higher concentration of alcohol contents in the solution. Mouth rinsing affected the remaining time of ethanol in mouth significantly reducing the alcohol concentration in mouth. The comparison of rinsing times and the remaining time of alcohol showed that breath alcohol test is not affected after 15 min. of the mouthwash use and the remained ethanol in mouth with the alcohol content less than 30%. Although it was determined that the breath alcohol concentration is not affected in the certain circumstance, it is necessary to take all factors(concentrations and types of alcohol, elapsed time after the consumption, individual metabolic differences, and other environmental conditions) to determine the breath alcohol concentration.

In this paper, we analyzed case of vehicle fire caused by the damage of ABS electronic control unit. A similar type of vehicle fire occurred in a car of the same manufacturer and as a result of investigating the cause of the fire. it was confirmed that a fire occurred at the connection terminal of the ABS electronic control unit. When an incomplete connection occurs from the connection portion, electric heat generated due to an increase in contact resistance and the electric heat in increased, which eventually leads to vehicle fire. The results of the case analysis can be used as sufficient basic data in the process of investigating the causes of vehicle fires.

In this paper, we introduce that the actual ignition point and the main combustion point may be different in case of a battery fire. In addition, the possibility of misuse of chargers could be suspected through precision investigation of different battery explosion cases. To verify this, an overvoltage applied experiment was conducted on a similar battery, and as a result of the experiment, it was confirmed that the P-IC module mounted in the PCM was preemptively damaged, and then the overcharged battery cell electrode led to an explosion.

Recently use of kitchen cookware is being changed from traditional methods using fuel such as a gas into the methods using electric energy. Depending on the increased use of electric ranges which are most typical in the kitchen, major changes in the course of the fire surfaces are being investigated. Therefore, in this study, the type of accident was analyzed due to electric range through the experimental method utilizing fire case analysis and electric range according to electric range. It can be seen that fire has occurred inadvertently and frequently through accidents and experimental analysis and it was confirmed that the occurrence of fire accident is possible even though electric range of induction heating method was no in direct contact with cookware.

Reverberation degrades speech quality, and impairs speech intelligibility. This degradation can also cause difficulties in the process of analyzing speech signals and conducting scientific investigations. In addition, in case of reverberant speech, since the performance of speech recognition is degraded, dereverberation technique is widely employed as a preprocessing. In this paper, we compare the performance of various neural vocoders in a dereverberation technique based on convolutional neural network(CNN). The U-Net architecture was utilized for dereverberation, and WaveGlow, MelGAN, and Griffin Lim were employed as vocoders. These vocoders have a role of receiving speech features as input and reconstruct to speech signals in time-domain. In particular, recent neural vocoders receive mel-spectrogram as an input feature and can reconstruct to high-quality speech signals. To compare the performance of the neural vocoder, we measured perceptual evaluation of speech quality(PESQ), and it was confirmed that all values were relatively high compared to the existing reverberant signals.

It is very important to determine whether ethanol(ethyl alcohol, EtOH) detection is due to EtOH of drinking or fermentation EtOH of postmortem. Fermentation EtOH can be simply produced in a short period of time, therefore, it makes a clear distinction between fermentation EtOH and EtOH of drinking. It was necessary to suspect the possibility that the detection of EtOH was determined less than 0.50 g/L of EtOH. In the case of this study, the woodworker died in a fall while working, 0.24 g/L of EtOH was detected, and n-propanol(n‒PrOH) and n-butanol(n‒BuOH) of indicator in the decomposed body were not detected. Further analysis of ethyl glucuronide(EtG) and ethyl sulfate(EtS) showed that EtG was 0.26 mg/L, and EtS was 0.14 mg/L. The results confirmed that the worker was drunk during the incident. Moreover, when the EtOH‒to‒EtG ratio in blood(EtOH in g/L, EtG in mg/L) and EtG or EtS concentration(mg/L) are determined, the drinking time and the amount of the drinking can be estimated. According to our previous results with reference, in the case of the worker could be estimated to drink about 3‒4 hours, and the amount of EtOH was about 0.5 g/kg(EtOH dose/body weight). Therefore, two subsequent EtG/EtOH ratio and EtG or EtS in blood supports information of recent drinking.

A goat that had been grazing was found dead. Autopsy found needle-like substances presumed to be yew leaves in the stomach, and yew ingestion was suspected. In the screening using gas chromatography-mass spectrometry(GC–MS), 3,5-dimethoxyphenol, the aglycone of taxicatine which is a typical ingredient of yew leaves, was identified as indirect evidence of yew ingestion, and toxicological analysis for compounds of yew, taxoids, was performed based on liquid–liquid extraction, followed by liquid chromatography–quadrupole time-of-flight mass spectrometry(LC–QTOF–MS) without reference standards. Using the analytical method, we determined six taxoids, namely taxine B, cephalomannine, paclitaxel, 10-deacetyltaxol (10-DAT), baccatin III, and 10-deacetylbaccatin III(10-DAB III), in the stomach contents. Based on these results of toxicological analysis, especially the determination of taxine B, and morphological finding, yew poisoning was proven as the cause of death.