• 상하수도학회지
• /
• 제24권6호
• /
• pp.775-788
• /
• 2010

The decomposition of 2,4,6-trinitrotoluene (TNT) and the mass balance of nitrogen (N) species as products were investigated in a UV/H2O2system by varying pH, concentrations of $H_2O_2$, and $O_2$. All experiments were conducted in a semi-batch system employing a 50 mL reaction vessel and a coil-type quartz-tube reactor. In contrast with previous studies employing batch mode, TNT decomposition in the semi-batch mode was proportionally enhanced by increasing $H_2O_2$ concentration to 10 mM (0.034%), indicatingthat an inhibitory effect of excess $H_2O_2$on hydroxyl radical (${\cdot}OH$) can be negligible. N compounds are released as $NO_2^-$ in the early stages of the reaction, but $NO_2^-$ is rapidly oxidized to $NO_3^-$ by means of ${\cdot}OH$. $NH_4^+$ was also detected in this study and showed gradually the increase with increasing reaction time. In this study, $NH_4^+$ production can involve the reduction of nitro group of TNT concurrent with the production of $NO_3^-$. Of the N species originating from TNT decomposition, 12 ~ 72% were inorganic forms (i.e. [$NO_3^-$] + [$NO_2^-$] + [$NH_4^+$]). This result suggests that the large remaining N portions indicate that unidentified N compounds can exist.

• 대한기계학회논문집A
• /
• 제36권10호
• /
• pp.1109-1114
• /
• 2012

제품 생산 시 발생하는 제작 공차, 항복강도와 탄성계수 등 재료 물성치의 불확실성, 온도와 습도 같이 시스템에 작용하는 환경인자 등은 시스템의 성능에 영향을 미친다. 강건 최적설계는 이러한 인자들이 시스템에 미치는 영향을 최소화하면서 성능을 개선하는 설계기법으로 최근 많은 연구가 이루어지고 있다. 하지만 기존의 강건 최적설계 기법은 여러 인자들의 분포를 고려해야 하기 때문에 막대한 계산비용이 드는 문제가 있다. 본 논문에서는 이러한 문제점을 개선하기 위하여 곱분해 기법을 이용한 강건 최적설계를 제안한다. 제안된 기법을 이용하여 설계영역을 크리깅 메타모델로 근사하고 곱분해 기법을 적용하여 평균과 분산을 효율적이고 정확하게 계산하여 강건 최적설계를 수행한다. 제안된 방법을 수학예제와 공학예제에 적용하여 유용성을 검증한다.

• Nuclear Engineering and Technology
• /
• 제9권4호
• /
• pp.211-222
• /
• 1977

고준위 방사성 폐액의 고화처리 방법들 중 하나인 Vitrification Process의 연구로서 핵연료 재처리 과정에서 유출되는 가상적인 비활성폐액 중에 함유되어 있는 분열 및 부식 생성물들의 질산화물과 유리화시키기 위해 사용되는 첨가제의 열분해에 관하여 연구 조사되었다. 결정수를 갖고 있는 화합물들의 열분해시점은 75$^{\circ}C$이하였지만, 무수화합물들은 비교적 높은 분포를 보였다. 110$0^{\circ}C$까지 가열하여 얻어진 질량손실율을 이론치와 비교하였을 때, 대부분의 화합물은 릴치하거나 근사하였지만, Sodium, Cesium, Lithium, Ruthenium 등의 질산화물의 질량손실율은 이론치 보다 훨씬 높았다. 여기서 얻어진 결과는 고준위 폐액의 가소처리과정 또는 조사된 화합물들의 혼합에 따른 열분해를 분석하는데도 이용될 수 있을 것이다.

• 상하수도학회지
• /
• 제33권6호
• /
• pp.469-480
• /
• 2019

This study was conducted to evaluate the degradation and mineralization of PPCPs (Pharmaceuticals and Personal Care Products) using a CBD(Collimated Beam Device) of UV/H₂O₂ advanced oxidation process. The decomposition rate of each substance was regarded as the first reaction rate to the ultraviolet irradiation dose. The decomposition rate constants for PPCPs were determined by the concentration of hydrogen peroxide and ultraviolet irradiation intensity. If the decomposition rate constant is large, the PPCPs concentration decreases rapidly. According to the decomposition rate constant, chlortetracycline and sulfamethoxazole are expected to be sufficiently removed by UV irradiation only without the addition of hydrogen peroxide. In the case of carbamazepine, however, very high UV dose was required in the absence of hydrogen peroxide. Other PPCPs required an appropriate concentration of hydrogen peroxide and ultraviolet irradiation intensity. The UV dose required to remove 90% of each PPCPs using the degradation rate constant can be calculated according to the concentration of hydrogen peroxide in each sample. Using this reaction rate, the optimum UV dose and hydrogen peroxide concentration for achieving the target removal rate can be obtained by the target PPCPs and water properties. It can be a necessary data to establish design and operating conditions such as UV lamp type, quantity and hydrogen peroxide concentration depending on the residence time for the most economical operation.

• 한국산업융합학회 논문집
• /
• 제25권6_3호
• /
• pp.1275-1284
• /
• 2022

This study provides an investigating the electrolyte reaction characteristics during thermal runaway of a lithium-ion battery(LIB). Dimethyl carbonate(DMC) is known as the main substance that makes up the electrolyte. The mono-molecular decomposition characteristics of DMC were derived through numerical analysis. Cobalt oxide can release oxygen under high temperature conditions. Also, DMC is converted to CH₄, H₂, CO, and CO₂. Especially, it was found that the decomposition of the DMC begins at a temperature range of 340-350℃, which dramatically increases the internal pressure of the LIB. In the by-products gases, the molar ratio of CO and CO₂ changed according to the molecular structure of DMC and temperature conditions. The correlation of the [CO]/[CO₂] ratio according to the temperature during thermal runaway was derived, and the characteristics of the reaction temperature could be estimated using the molar ratio as an indicator. In addition, the oxidation and decomposition characteristics of DMC according to the residence time for each temperature were estimated. When DMC is exposed to low temperature for a long time, both oxidation and decomposition may occur. There is possibility of not only increasing the internal pressure of the LIB, but also promoting thermal runaway. In this study, internal environment of LIB was identified and the reaction characteristics between the active materials of the cathode and electrolyte were investigated.

• 대한전자공학회논문지
• /
• 제24권1호
• /
• pp.173-176
• /
• 1987

This paper presents a simple factorization of the Hadamard matrix which is used to develop a fast algorithm for the Hadamard transform. This matrix decomposition is of the kronecker products of identity matrices and successively lower order Hadamard matrices. This following shows how the Kronecker product can be mathematically defined and efficiently implemented using a factorization matrix methods.

• 호남수학학술지
• /
• 제35권1호
• /
• pp.1-15
• /
• 2013

In this paper, we study a sheaf-theoretic analysis of the convolution algebra on quiver varieties. As by-products, we reinterpret the results of H. Nakajima. We also produce a refined form of the BBD decomposition theorem for quiver varieties. Finally, we study a construction of highest weight modules through constructible functions.

• 대한수학회논문집
• /
• 제32권4호
• /
• pp.999-1008
• /
• 2017

By mainly using certain properties arising from the semisimple Lie group SO(2, 1), we aim to show how a family of some interesting formulas for bilateral series and integrals involving Whittaker, Bessel functions, and their product can be obtained.

• 대한수학회지
• /
• 제54권6호
• /
• pp.1841-1851
• /
• 2017

Motivated by the Bloch-Beilinson conjectures, Voisin has made a conjecture concerning zero-cycles on self-products of Calabi-Yau varieties. We reformulate Voisin's conjecture in the setting of $hyperk{\ddot{a}}hler$ varieties, and we prove this reformulated conjecture for one family of $hyperk{\ddot{a}}hler$ fourfolds.

• Journal of Nutrition and Health
• /
• 제20권1호
• /
• pp.10-14
• /
• 1987

The effect of the addition of the white powder separated from Sogi (Gyrophora esculenta) by the extraction methods with ethanol and acetone was checked by the feeding experiment in rats fed with a high cholesterol diet. From this experiment, it was confirmed that this material, which was assumed to be the mixture of gyrophoric acid and the decomposition products, could lower both liver and plasma cholesterol levels.