• Bulletin of the Korean Chemical Society
• /
• 제34권12호
• /
• pp.3659-3664
• /
• 2013

Eight representative explosives (ammonium perchlorate (AP), ammonium nitrate (AN), trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), cyclonite (RDX), cyclotetramethylenetetranitramine (HMX), pentaerythritol tetranitrate (PETN), and hexanitrostilbene (HNS)) were comprehensively analyzed with an ion trap mass spectrometer in negative ion mode using direct infusion electrospray ionization. MS/MS experiments were performed to generate fragment ions from the major parent ion of each explosive. Explosives in salt forms such as AP or AN provided cluster parent ions with their own anions. Explosives with an aromatic ring were observed as either $[M-H]^-$ for TNT and DNT or $[M]^{{\cdot}-}$ for HNS, while explosives without an aromatic ring such as RDX, HMX, and PETN were detected as an adduct ion with a formate anion, i.e., $[M+HCOO]^-$. These findings provide a guideline for the rapid and accurate detection of explosives once portable MS instruments become more readily available.

• 비파괴검사학회지
• /
• 제26권3호
• /
• pp.174-180
• /
• 2006

Steam generator (SG) tubes are expanded inside tubesheet holes by using explosive or hydraulic methods to be fixed in a tubesheet. In the tube expansion process, it is important to minimize the crevice gap between expanded tube and tube sheet. In this paper, absolute and differential signals are computed by a numerical method for several different locations of tube expansion inside and outside a tubesheet and signal variations due to tubesheet, tube expansion and operating frequencies are observed. Results show that low frequency is good for detecting tubesheet location in both types of signals and high frequency is suitable for sizing of tube diameter as well as the detection of transition region. Also learned is that the absolute signal is good for measuring tube diameter, while the differential signal is good for locating the top of tubesheet and both ends of the transition region. In the case of mingled anomaly with tube expansion and tubesheet, low frequency inspection is found to be useful to analyze the mixed signal.

• 대한안전경영과학회지
• /
• 제19권3호
• /
• pp.1-9
• /
• 2017

In the industrial field, various type of fuel have been used for product processing facilities. Recent for 10 years, the usage of natural gas (NG) was gradually increased. Because it has many merits; clean fuel, no transportation, storage facility and so on. There are common safety concept that strict explosion protection approaches are needed for facilities where explosive materials such as flammable liquid, vapor and gases exist. But some has an optimistic point of view that the lighter than air gases such as NG disperse rapidly, hence do not form explosion environment upon release into the atmosphere, many parts has a conventional safety point of view that those gases are also inflammable gases, hence can form explosion environment although the extent is limited and present. In this paper, the heating equipments (Hot Oil Heater) was reviewed and some risk management measures were proposed. These measures include hazardous area classification and explosion-proof provisions of electric apparatus, an early gas leak detection and isolation, ventilation system reliability, emergency response plan and training and so on. This study calculates Hazardous Area Classification using the hypothetical volume in the KS C IEC code.

• Bulletin of the Korean Chemical Society
• /
• 제31권12호
• /
• pp.3703-3706
• /
• 2010

Biomolecules specific to explosives can be exploited as chemical sensors. Peptides specific to immobilized dinitrotoluene (DNT) were identified using a phage display library. A derivative of DNT that contained an extended amine group, 4-(2,4-dinitrophenyl)butan-1-amine, was synthesized and immobilized using a self-assembled monolayer surface on gold. Filamentous M13 phages displaying random sequences of 12-mer peptides specific to the immobilized DNT-derivate were isolated from the M13 phage library by biopanning. A common peptide sequence was identified from the isolated phages and the synthesized peptides showed selective binding to DNT. When the peptide was immobilized on a quartz crystal microbalance (QCM) chip, it showed a binding signal to DNT, while toluene barely showed significant binding to the QCM chip. These results demonstrate that peptides screened by biopanning against immobilized DNT can be useful for quick and accurate detection of DNT.

• 센서학회지
• /
• 제29권6호
• /
• pp.382-387
• /
• 2020

Hydrogen (H₂) is considered as a new clean energy resource for replacing petroleum because it produces only H₂O after the combustion process. However, owing to its explosive nature, it is extremely important to detect H₂ gas in the ambient atmosphere. This has triggered the development of H₂ gas sensors. 2-dimensional (2D) graphene has emerged as one of the most promising candidates for chemical sensors in various industries. In particular, graphene exhibits outstanding potential in chemoresistive gas sensors for the detection of diverse harmful gases and the control of indoor air quality. Graphene-based chemoresistive gas sensors have attracted tremendous attention owing to their promising properties such as room temperature operation, effective gas adsorption, and high flexibility and transparency. Pristine graphene exhibits good sensitivity to NO₂ gas at room temperature and relatively low sensitivity to H₂ gas. Thus, research to control the selectivity of graphene gas sensors and improve the sensitivity to H₂ gas has been performed. Noble metal decoration and metal oxide decoration on the surface of graphene are the most favored approaches for effectively controlling the selectivity of graphene gas sensors. Herein, we introduce several strategies that enhance the sensitivity of graphene gas sensors to H₂ gas.

• KEPCO Journal on Electric Power and Energy
• /
• 제6권4호
• /
• pp.405-411
• /
• 2020

In this paper, we designed the COS MEMS system for sensing the falling detection and explosive noise of fuse link in COS (Cut Out Switch) installing on the power distribution. This system analyzed the failure characteristics and an instantaneous breakdown of power distribution. Therefore, our system strengths the industrial competence and guaranties the stable power supply. In this paper, we applied BLE (Bluetooth Low Energy) technology which is suitable protocol for low data rate, low power consumption and low-cost sensor applications. We experimented with LSM6DSOX which is system-in-module featuring 3 axis digital accelerometer and gyroscope boosting in high-performance mode and enabling always-on low-power features for an optimal motion for the COS fuse holder. Also, we used the MP34DT05-A for gathering an ultra-compact, low power, omnidirectional, digital MEMS microphone built with a capacitive sensing element and an IC interface. The proposed COS MEMS system is developed based on nRF52 SoC (System on Chip), and contained a 3-axis digital accelerometer, a digital microphone, and a SD card. In this paper of experiment steps, we analyzed the performance of COS MEMS system with gathering the accelerometer raw data and the PDM (Pulse Data Modulation) data of MEMS microphone for broadcasting the failure of COS status.

• 한국전기전자재료학회논문지
• /
• 제37권4호
• /
• pp.347-357
• /
• 2024

Oxide semiconductor gas sensors are widely used for detecting toxic, explosive, and flammable gases due to their simple structure, cost-effectiveness, and potential integration into compact devices. However, their reliable gas detection is hindered by a longstanding issue known as humidity dependence, wherein the sensor resistance and gas response change significantly in the presence of moisture. This problem has persisted since the inception of oxide semiconductor gas sensors in the 1960s. This paper explores the root causes of humidity dependence in oxide semiconductor gas sensors and presents strategies to address this challenge. Mitigation strategies include functionalizing the gas-sensing material with noble metal/transition metal oxides and rare-earth/rare-earth oxides, as well as implementing a moisture barrier layer to prevent moisture diffusion into the gas-sensing film. Developing oxide semiconductor gas sensors immune to humidity dependence is expected to yield substantial socioeconomic benefits by enabling medical diagnosis, food quality assessment, environmental monitoring, and sensor network establishment.

• 한국지구과학회지
• /
• 제41권5호
• /
• pp.478-489
• /
• 2020

대기 압력 변동을 측정하는 인프라사운드 관측 기술을 통하여 원거리 지표폭발 사고를 분석하였다. 2019년 12월 24일 전남 광양시에서 발생한 2차례 폭발 사고에서 발생한 인프라사운드 신호가 151-435 km 거리에 위치하는 12개 음파 관측소에 기록되었다. 당시 인프라사운드는 북북서 방향의 성층권 바람에 의해 약 40 km 고도에서 굴절되어 같은 방향에 분포하는 관측소에 도달하였다. 반면, 약 10 km 고도에서는 강한 서풍의 영향으로 대류권 굴절 신호가 북동 및 동쪽 방향에 위치하는 관측소에 도달하는 등 방향에 따라 상이한 전파 경로를 보였다. 대기 유효음파속도구조와 포물선 방정식 모델링을 통해 전파 경로상의 투과손실을 계산하고 폭발 지점으로부터 기준거리에서의 초과압력을 추정하였다. 추정된 초과압력은 초과압력-폭발량 관계식에 적용함으로써, 두 차례의 폭발은 각각 14, 65 kg TNT 폭발 에너지에 상응하는 것으로 계산되었다. 1차 폭발 당시에 폭발 충격으로 부속물이 대기 중으로 비산하는 현상이 관측되었고, 폭발충격에 의한 파편 운동과 초과압력 간의 관계식으로 1차 폭발의 에너지는 약 49 kg 이하 TNT 폭발에 상응하는 것으로 계산되었다. 본 연구에서 제안한 폭발 에너지 추정 방법은 향후 다양한 원거리 폭발 에너지 계산에 활용이 가능하리라 본다. 향후 계산 결과의 신뢰도를 높이기 위해서는 대기 속도구조 불확실성에 대한 연구와 다양한 발파 자료를 통한 검증 연구가 필요하다.

• 한국광학회지
• /
• 제28권4호
• /
• pp.166-171
• /
• 2017

수소 가스는 연소과정에서 오염물질의 배출이 없는 친환경 에너지원이다. 그러나 연소 및 폭발성이 매우 강해 매우 위험한 특징을 갖고 있다. 원자력 발전소의 중대 사고 발생시 핵연료의 산화 과정에서 다량의 수소 가스가 발생하며 원전 격납 건물의 2차 사고의 원인으로 작용함으로 원전의 안전을 확보하기 위하여 수소 가스의 검출 기술은 매우 중요하다. 본 논문은 수소 가스의 원격 계측을 위한 라만 라이다 시스템의 개발에 관한 것이다. 소형의 이동 가능한 라만 라이다 시스템을 설계 및 개발하였으며, 수소 가스의 농도를 정량적으로 계측하기 위한 계측 알고리즘을 개발하였다. 개발된 수소 가스 계측을 위한 라만 라이다 시스템의 수소 가스 검출 능력을 검증하기 위하여 수소 가스의 농도를 조절할 수 있는 가스 챔버를 이용하여 낮에 야외 환경에서 수소 가스 검출 실험을 실시하였다. 그 결과 20미터 거리에서 최소 0.67 Vol.%의 수소 가스 농도의 검출이 가능하였다.

• 한국결정성장학회지
• /
• 제33권6호
• /
• pp.255-260
• /
• 2023

분자 단위의 폭발물질을 탐지하기 위하여, 고감도 응답성 센서의 개발이 요구되고 있다. 2차원 반도체는 얇은 적층형 구조를 가져 전하 캐리어가 축적될 수 있어, 전하 캐리어의 급격한 신호 변조 특성을 기대할 수 있다. WSe₂ 반도체 소재의 TNT(Trinitrotoluene) 폭발물질에 대한 탐지 효용성을 연구하기 위해, CVD(Chemical Vapor Deposition) 공정을 이용해 WSe₂ 박막을 합성하여 FET(Field Effect Transistors)을 제작하였다. 라만 분석과 FT-IR(Fourier-transform infrared) 분광 결과는 TNT 분자의 흡착과 WSe₂ 결정질의 구조적 전이 분석 정보를 나타내었다. 또한, WSe₂ 표면의 TNT 분자 흡착 전후의 전기적 특성을 비교하였다. TNT 도포 전, WSe₂ FET에 백 게이트 바이어스로 -50 V를 인가함에 따라 0.02 μA의 최대 전류 값이 관측되었고, 0.6%(w/v) TNT 용액을 도포하였을 때 Drain 전류는 p-type 거동을 보이면서 0.41 μA의 최대 전류 값을 기록하였다. 이후 On/Of f Ratio 및 캐리어 이동도, 히스테리시스를 추가적으로 평가하였다. 본 연구에서는 WSe₂의 TNT 분자에 대한 고감도와 신속한 응답성을 통해 폭발물질 탐지 센서 소재로서의 가능성을 제시하였다.