• 한국전산구조공학회논문집
• /
• 제30권2호
• /
• pp.145-151
• /
• 2017

콘크리트 구조물 또는 암석의 해체 공정에서 소음, 진동, 분진 등의 발생을 초래하는 기존의 발파공법을 대신하여 비폭성 파쇄제의 이용을 고려할 수 있다. 본 연구는 유한한 정사각형 콘크리트 구조물을 대상으로 하여 비폭성 파쇄제의 팽창이 준정적으로 균열을 발생, 진전시키는 과정을 유한요소해석으로 예측하고 기존 문헌에 보고된 실험결과와 비교함으로써 해석결과의 정확성을 검증하였다. 또한 비폭성 파쇄제 및 천공 홀의 배치에 따른 영향을 최소요구팽창압 관점에서 분석하였다. 더 나아가서 비폭성 파쇄제가 채워지지 않은 천공 홀이 비폭성 파쇄 공정에 미치는 영향을 분석하고, 분리 조각의 수를 증가시켜 파쇄도를 향상시키기 위한 비폭성 파쇄제 및 천공 홀의 효과적인 배치에 대하여 고찰하였다.

• 항공우주시스템공학회지
• /
• 제15권4호
• /
• pp.1-6
• /
• 2021

The non-explosive holding and release mechanism is used to prevent damage to the mission component caused by explosives when the deployment structure for Cube Satellites is separated. However, among the several types available, the non-explosive holding and release mechanism system using nylon wires depend on the nylon wire knot method and tightening power of the worker. Therefore, in this study, we conducted experiments with the operation of a new holding and release mechanism system by conceptualizing the Boa System Dial, which can provide a constant tightening force regardless of worker proficiency and deploying a imitational solar panel. In this study, the process of binding and unbinding with constant tension was recorded while applying the novel non-explosive holding and release mechanism using the Boa System Dial proposed. In addition, required advances are indicated for the application of the proposed system to actual Cube Satellites.

• Journal of Welding and Joining
• /
• 제14권4호
• /
• pp.62-70
• /
• 1996

Al or Al-alloy have been known to be able to be claded on various materials by using explosive welding process, however, the intermetallic layer frequently formed along the interface have made this process very complicated. In this study, it was focussed to select the process variables, which can get rid of interfacial layer in the Al-claded steel plate. As a result, it was demonstrated that there was a certain range of explosive thickness which did not form the intermetallic phase as well as the non-bonded area. On the other hand, ultasonic tests performed for identifying the presence of interfacial layer nondestructively showed that it could be applied for the intended purpose but its result was weakly related with the microstructural quality of interface.

• Korean Chemical Engineering Research
• /
• 제58권3호
• /
• pp.493-497
• /
• 2020

Hazardous area classification is designed to prevent chemical plant explosions in advance. Generally, the duration of the explosive atmosphere is used for zone type classification. Herein, IEC code, a quantitative zone type classification methodology, was used to achieve Zone 2 NE, which indicates a practical non-explosion condition. This study analyzed the operating pressure of a vessel handling propane to achieve Zone 2 NE by applying the IEC code via MATLAB. The resulting zone type and hazardous area grades were compared with the results from other design standards, namely API and EI codes. According to the IEC code, the operating pressure of vessels handling propane should be between 101325-116560.59 Pa. In contrast, the zone type classification criteria used by API and EI codes are abstract. Therefore, since these codes could interpret excessively explosive atmospheres, care is required while using them for hazardous area classification design.

• 대한화학회지
• /
• 제57권1호
• /
• pp.109-114
• /
• 2013

The effects of aluminum nanoparticles (AlNs) on the thermal decomposition of ammonia perchlorate (AP) were investigated by DSC, TG-DSC and DSC-TG-MS-FTIR. Addition of AlNs resulted in an increase in the temperature of the first exothermic peak of AP and a decrease in the second. The processing of non-isothermal data at various heating rates with and without AlNs was performed using Netzsch Thermokinetics. The dependence of the activation energy calculated by Friedman's isoconversional method on the conversion degree indicated the decomposition process can be divided into three steps. They were C1/D1/D1 for neat AP, determined by Multivariate Non-linear Regression, and changed to C1/D1/F2 after addition of AlNs into AP. The isothermal curves showed that the thermal stability of AP in the low temperature stage was improved in the presence of AlNs.

• 한국분말재료학회지
• /
• 제10권5호
• /
• pp.310-317
• /
• 2003

Two-component ceramic (alumina-zirconia) composites were fabricated by a soft-solution process in which polyethylene glycol (PEG) was used as a polymeric carrier. Metal salts and PEG were dissolved in ethyl alcohol without any precipitation in 1:1 volume ratio of alumina and zirconia. In the non-aqueous system, the flammable solvent made explosive, exothermic reaction during drying process. The reaction resulted in formation of volume expanded, porous precursor powders by a vigorous decomposition of organic components in the precursor sol. The PEG content affected the grain size of sintered composites as well as the morphology of precursor powders. The difference of microstructure in sintered composite was attribute to the solubility and homogeneity of metal cations in precursor sol. At the optimum amount of the PEG polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. It made less agglomerated particles in the precursor sol and affected on uniform grain size in sintered composite.

• Safety and Health at Work
• /
• 제12권3호
• /
• pp.416-420
• /
• 2021

Hazardous area classification design is required to reduce the explosion risk in process plants. Among the international design guidelines, only IEC 60079-10-1 proposes a new type of zone, namely zone 2 NE, to prevent explosion hazards. We studied how to meet the zone 2 NE grade for a facility handling hydrogen gas, which is considered as most dangerous among explosive gases. Zone 2 NE can be achieved considering the grade of release, as well as the availability and effectiveness of ventilation, which are factors indicative of the facility condition and its surroundings. In the present study, we demonstrate that zone 2 NE can be achieved when the degree of ventilation is high by accessing temperature, pressure, and size of leak hole. The release characteristic can be derived by substituting the process condition of the hydrogen gas facility. The equations are summarized considering relation of the operating temperature, operating pressure, and size of leak hole. Through this relationship, the non-hazardous condition can be realized from the perspective of inherent safety by the combination of each parameter before the initial design of the hydrogen gas facility.

• 한국컴퓨터정보학회지
• /
• 제8권2호
• /
• pp.67-74
• /
• 2001

최근에 이용 가능한 데이터의 양이 폭발적으로 증가하고 있다 따라서 이들 데이터로부터 유용한 지식을 발견하는 자동화된 기법이 주목을 받고 있다. 데이터 마이닝이란 지식 발견의 중요한 단계로서, 데이터로부터 유용한 패턴을 발견하는 방법이다. 본 논문에서는 데이터 마이닝 기법을 조사한다 이러한 조사과정을 통하여 실세계에서 보다 효율적으로 적용 가능한 데이터 마이닝 기법을 찾아내고. 이들 기법에 대한 적절한 응용 영역과 앞으로의 연구방향을 제시한다.

• 한국군사과학기술학회지
• /
• 제17권6호
• /
• pp.718-724
• /
• 2014

Insensitive Munition(IM) reduces the explosive weakness of munitions, at the same time, maintains its performances in the moment of discharge, which improves safety of soldiers and minimizes unexpected accidents and casualties from being shot in case of transportation, storage and military operation. Development of IM has been focused as the global trend, which was required to satisfy the demand of army that is to minimize the loss of non-battle forces and to retain the competitiveness in export abroad. In this study, we categorize all the munitions used by ROK Army, then determine the priority of IM by deploying AHP(Analytic Hierarchy Process) method. In conclusion, we suggest the priority of IM which is suitable to the affairs of ROK Army.

• IMMUNE NETWORK
• /
• 제11권3호
• /
• pp.135-154
• /
• 2011

The great discovery of microRNAs (miRNAs) has revolutionized current cell biology and medical science. miRNAs are small conserved non-coding RNA molecules that post-transcriptionally regulate gene expression by targeting the 3' untranslated region of specific messenger RNAs for degradation or translational repression. New members of the miRNA family are being discovered on a daily basis and emerging evidence has demonstrated that miRNAs play a major role in a wide range of developmental process including cell proliferation, cell cycle, cell differentiation, metabolism, apoptosis, developmental timing, neuronal cell fate, neuronal gene expression, brain morphogenesis, muscle differentiation and stem cell division. Moreover, a large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as cancer, psychiatric and neurological diseases, cardiovascular disease, and autoimmune disease. Interestingly, in addition, miRNA deficiencies or excesses have been correlated with a number of clinically important diseases ranging from cancer to myocardial infarction. miRNAs can repress the gene translation of hundreds of their targets and are therefore well-positioned to target a multitude of cellular mechanisms. As a consequence of extensive participation in normal functions, it is quite logical to ask the question if abnormalities in miRNAs should have importance in human diseases. Great discoveries and rapid progress in the past few years on miRNAs provide the hope that miRNAs will in the near future have a great potential in the diagnosis and treatment of many diseases. Currently, an explosive literature has focussed on the role of miRNA in human cancer and cardiovascular disease. In this review, I briefly summarize the explosive current studies about involvement of miRNA in various human cancers and cardiovascular disease.