• Journal of the Korea Institute of Military Science and Technology
• /
• v.27 no.2
• /
• pp.277-284
• /
• 2024

For the high reliability of guidance weapon, it is important to maintain the stable supply voltage for guidance system while the bomb is gliding. However, the DC motor drive for guidance control in the low temperature can lead to the critical voltage drop due to a large inrush current. In this paper, we propose the wing deployment logic design to enhance the guidance system stability. To derive the stable drive logic based on PWM, we controlled the duty cycles for input voltage of DC motor in low temperature. The initial duty cycle was set to 40 % to relieve the inrush current. Moreover, the proper time, which is less than 1 second for controlling duty cycles, was determined by the iterative wing deployments of guidance kit. Finally, the validity of proposed logic was confirmed from the result the maximum voltage drop for the wing deployment was decreased by 23 %.

• Convergence Security Journal
• /
• v.24 no.3
• /
• pp.219-229
• /
• 2024

The application of 4th Industrial Revolution technologies in the defense sector is accelerating, leading to the rapid incorporation of information and communication technologies (ICT) into military systems. The biggest threat to these ICT-based military systems is an electromagnetic pulse (EMP) attack, which can result from nuclear explosions or EMP bombs. North Korea's ongoing nuclear advancements and EMP bomb capabilities pose a critical threat, necessitating South Korea's preparedness for such attacks to ensure the effective operation of its ICT-based military systems. Despite this urgency, the South Korean military currently lacks comprehensive standards for EMP protection, relying only on the design criteria for EMP protection facilities for buildings. This gap highlights the absence of sufficient legal and regulatory measures and the lack of focused research to develop EMP protection performance standards for safeguarding military systems. Therefore, this paper aims to analyze existing EMP protection performance standards and relevant laws and regulations. It proposes improvements and establishes necessary standards to enhance the EMP resilience of military facilities and equipment.

• Journal of Energy Engineering
• /
• v.20 no.1
• /
• pp.36-43
• /
• 2011

Plant biomass has been proposed as an alternative source of petroleum-based chemical compounds. Especially, aromatic chemical compounds can be obtained from lignin by depolymerization processes because the lignin consist of complex aromatic materials. In this study, kraft lignin, the largest emitted substance among several kinds of lignin in Korea, was used as a starting material and was characterized by solid-state $^{13}C$-Muclear Magnetic Resonance($^{13}C$-NMR), Fourier Transform Infrared Spectroscopy(FT-IR), Elemental Analysis(EA). The depolymerization of kraft lignin was studied at water-phenol mixture solvent in near critical region and the experiments were conducted using a batch type reactor. The effects of water-to-phenol ratio and reaction temperature($300-400^{\circ}C$) were investigated to determine the optimum operating conditions. Additionally, the effects of formic acid as a hydrogen-donor solvent instead of $H_2$ gas were examined. The chemical species and quantities in the liquid products were analyzed using gas chromatography-mass spectroscopy(GC-MS), and solid residues(char) were analyzed using FT-IR. GC-MS analysis confirmed that the aromatic chemicals such as anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole and xanthene were produced when phenol was added in the water as a co-solvent.

• The Journal of Engineering Geology
• /
• v.24 no.3
• /
• pp.373-381
• /
• 2014

It is difficult to predict the magnitude of a rockfall with respect to the shape, volume, and weight of the rock mass, as a rockfall exhibits erratic behavior that depends on the slope geometry, such as the height and dip of the slope. In this study, a field survey was conducted on the slopes of Ulleung-Do, South Korea, where rockfalls frequently occur along coastal roads, to classify the mode of rockfalls and estimate their magnitude. This study also analyzed the effects of rockfall behavior on roads by applying a simulation technique. Agglomerate and trachytic rocks distributed across the study area produce rockfalls in a differential weathering rockfall mode and a toppling rockfall mode. In terms of rockfall weight, trachytic rockfalls were 2-3 times heavier than agglomerate rockfalls. An analysis of rockfall behavior from the simulation indicates that the impact energy on the road exceeded the absorbing energy of a standard rockfall protection fence; however, the rockfall was secured when a ring-net was applied.

• Journal of Life Science
• /
• v.20 no.12
• /
• pp.1829-1837
• /
• 2010

Mideoduck drips were mixed with amino acids (Met, Tau, Gly, Ala, Thr, Cys), thiamine and sugars (Glucose, Ribose) for flavor modification and evaluation using the Maillard reaction. To mask the seafood flavor, onions, spring onions, garlic, ginger, citric orange and green tea were mixed with Mideoduck drips at $160^{\circ}C$ for 2.5 hr in a stainless still reaction bomb. The glucose/thiamine model reaction system was estimated to be lower than the ribose/thiamine model system, and an extreme case is the ribose/Met model system. Mixed system of glucose, ribose and taurine containing sulfur compounds showed fair results. Among the Mideoduck drips mixed with sugars and amino groups, only thiamine model systems were estimated to be normal. The flavor composition of Mideoduck drips/sugars model system, and long chain fatty acids were composed of 31.32~62.71% total flavor content. The 1,2-benzenedicarboxylic acid dibutylester contents made up more than 20% of the model system in groups A, B and C. From the model system in this study, drip/glucose, drip/ribose, drip/glucose/citric orange, and drip/glucose/glycine/cystine groups showed most intense good flavor.

• Journal of the Korean Institute of Gas
• /
• v.18 no.1
• /
• pp.31-40
• /
• 2014

LNG storage outer tank is a vertically and horizontally prestressed concrete wall structure. Therefore, when the storage tanks become larger, prestressing tendons become longer and eventually the prestressing loss becomes larger. Also, recently, bomb terrors and accidental crashes have occurred frequently on important infrastructures. Therefore, LNG storage tanks are also exposed to these dangerous scenarios, where they need to be evaluated and protected from these threats. Therefore, in this study, the behavior of 270,000 kL LNG storage outer tank impacted by a flying object is evaluated using implicit FEM code, LS-DYNA. In the analysis, the prestress loss due to the increased length of prestressing tendons from enlargement of outer tank is considered. A comparison study between the LNG tanks with and without prestress loss is performed to investigate the impact behavior and the effect of prestressing force change on the safety and serviceability prestressed concrete containment.

• Analytical Science and Technology
• /
• v.16 no.2
• /
• pp.117-124
• /
• 2003

Oxygen to metal ratio has been measured by wet and dry chemical analysis to study the properties of sintered $UO_2$ pellets and $U_3O_8$ in the lithium reduction process of spent pressurized water reactor fuels. Uranium dioxide pellets simulated for the spent PWR fuels with burnup values of 20,000~60,000 MWd/MtU were prepared by mixing $UO_2$ powder and oxides of fission product elements, pelleting the powder mixture and sintering it at $1,700^{\circ}C$ under a hydrogen atmosphere. For wet chemical analysis, the simulated spent fuels were dissolved with mixed acid (10 M HCl : 8 M $HNO_3$, 2.5 : 1, v/v) using acid digestion bomb technique. The total amount of uranium and fission products added in the simulated spent fuels were measured using inductively coupled plasma atomic emission spectrometry. Weight change of the simulated fuel during its oxydation was measured by thermogravimetry and then the O/M ratio result was compared to that obtained by wet chemical analysis. Influence of $Mo_{0.4}-Ru_{0.4}-Rh_{0.1}-Pd_{0.1}$, quaternary alloy, on the determination of O/M ratio was investigated.

• Analytical Science and Technology
• /
• v.12 no.6
• /
• pp.484-489
• /
• 1999

The extraction of trace amounts of Se in volcanic rock was investigated using the hydride generation method and atomic absorption spectrophotometry. The powdered rock, 1.0 g, was decomposed with the mixture of $HClO_4$, $HNO_3$ and HF in an acid digestion bomb at $140^{\circ}C$ for 2 hours. For the reduction of Se(VI) to Se(IV) in the solution, 10 mL of 6 M HCl and 0.2 mL of 1 M KBr were added to the solution and the mixture was heated for 30~45 minutes. $H_2Se$ was produced by adding 3% $NaBH_4$ as a strong reducing agent, extracted by nitrogen gas, and was absorbed twice into $KMnO_4$solution. The contents of Se in the solution were determined by generation/AAS. According to the proposed method, 1.0 ng or more of Se was quantitatively extracted and Se levels of 2.5 ng/g or more in rock samples could be determined. For example, Se in a rhyolite was determined with the precision of $19.5{\pm}1.3ng/g$(95% confidence, n=6).

• Analytical Science and Technology
• /
• v.13 no.3
• /
• pp.291-296
• /
• 2000

The SIMFUEL which composition is similar to PWR nuclear spent fuels was dissolved with a acid digestion bomb. An analytical conditions of ICP-AES for the direct determination of molybdenum in the uranium matrices without separation process were investigated. Based on the effect of uranium on molybdenum intensity. the most optimum wavelengths of molybdenum were found to be 202.030 and 203.844 nm. However, the method of standard additions is applied to overcome the effects of changing background caused by analyzing the sample solutions containing high concentration of uranium and the standard calibration solutions. The relative error of two methods, direct and indirect measurements with cation exchange resin separation procedures, was less than 5%. Therefore it was possible for this procedure to directly measure molybdenum in uranium matrices without separation. And this method was also applied to the determination of several percent of molybdenum in a U-Mo alloy.

• Korean Security Journal
• /
• no.22
• /
• pp.65-90
• /
• 2010

Recently, alarmed by the frequent international terrorism or safety accidents, the host countries of world sports events are focusing on security activities for the sake of the participants, facilities, events and competitions. They are alarmed because in case any happenings like international terrorism or safety accident, the contest itself can be criticized to be a failure as much as the international reliability of the host nation may well crash. We can see that any failure in coping with terrorism or safety matters can lead to a nation-wise crisis in the case of Indonesia where the October 12th of 2002 terrorist bomb attack in Bali damaged the image of the nation followed by the similar case in Philippine (Oct. 20th, 2002) where the same terrorist attack dramatically scared away the tourists to the nation. Korea is scheduled to hold the World Championship in Athletics in Daegu Metropolitan City in 2011. Also, it is slated to host various world sports events such as Yeosu International Exposition and Incheon Asian Games. In these contexts, this study analyzes counter-terrorism cases related with the recent international sports events that have been organized in a variety of manners in the era of globalization. This study aims to show alternatives for the safety management in these events. In other words, it is focusing on giving directions to the safety policies of the nation -which may become the future hub of north-east Asia and the world - for more perfect guard and defense, and counter-terrorism activities in all the conferences, sports events and international festivals where any private defense and guard companies are allowed to cooperate with the police force or public security agencies.