• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.128-130
• /
• 2017

$NaBH_4$ was added to improve the water reactivity of aluminum powder as a solid propellant for underwater propulsion. Aluminum powders showed different combustion characteristics depending on the amount of $NaBH_4$ added. When $NaBH_4$ was added, it was burned by reaction with water even at a temperature much lower than the boiling point. In this study, it was confirmed that $NaBH_4$ is an effective additive to accelerate the vapor reaction with Al powder.

• Applied Chemistry for Engineering
• /
• v.34 no.6
• /
• pp.567-575
• /
• 2023

Water electrolysis is undergoing active research as one of the promising technologies for producing effective green hydrogen. Using seawater directly as a raw material for a water electrolysis system can solve the problem of the limitations of existing freshwater raw materials, as seawater accounts for approximately 97% of the water on Earth. At the same time, abundant by-product materials can be obtained, representative examples of which are Cl₂, ClO^-, Br₂, and Mg(OH)₂ produced during electrolysis, depending on their composition and pH environment. In order to develop a successful seawater electrolysis system and oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysts, it is necessary to understand the causes and consequences of reactions that occur in the seawater environment. Therefore, in this paper, we will investigate the reaction mechanism and characteristics of the seawater electrolysis system as well as the research and development trends of electrochemical catalysts used in anode and cathode electrodes.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.103-115
• /
• 1981

The cathodic reactions of lead anodic films formed in phosphoric acid, oxalic acid and sodium hydroxide solutions and the reactivities of Di-iso-butylnitrosoamine (DBNA) in sea water at $15\sim30^{\circ}C$ were studied by means of constant current-potential method. Besides, various contants and thermodynamic quantities obtained in the experiment were also do-scribed to explain the reactivities of protons that entered in the anodic film by being transferred across the metal-oxide interface. The electrode reactions of lead anodic film formed in sodium hydroxide solution in 60mM DBNA+0.5M NaCl did not occur because of complete insulator formed on anodic film. The values of $(\partial\triangle E_{H^+}/\partial T)_{i=const}$, estimated with Bead anodic films formed in phosphoric acid in 60mM DBNA+0.5M NaCl and 60mM $DBNA+6\%_{\circ}$ sea water were $-0.006\;V/^{\circ}C\;and\;-0.005\;V/^{\circ}C$, thus being nearly coincided, but the values of $(\partial E_o/\partial T)_{i=o}$ were $0.002\;V/^{\circ}C\;and\;-0.002\;V/^{\circ}C$, being completely inversed.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.5
• /
• pp.129-137
• /
• 1998

본 연구에서는 해수 및 염화나트륨이 공급되는 환경에서 실리카 흄의 알칼리실리카 반응에 대한 억제효과를 구명한 것이다. 연구에 사용된 염화나트륨 농도는 2.8%, 10%, 20%여Tdmaum 반응성 골재는 일본산 안산암이었다. 실리카 흄은 노르웨이산으로 비표면적인 20$m^2$/g인 것을 사용했다. 실리카 흄의 치환율은 시멘트 중량에 대해 5%, 7%, 10%로 하였다. 연구결과, 20%의 염화나트륨이 공급되는 환경에서 알칼리실리카반응에 의한 유해한 팽창이 억제는 본 연구에서 사용된 실리카 흄의 경우, 치환율 % 이상에서 달성되었다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.583-586
• /
• 2003

부산 동래지역 지열수에 대한 지화학적 진화과정을 밝히기 위하여 지열수, 지하수 및 해수에 대한 수리화학 특성과 이들의 연관성을 고찰하였다. 또한 심부환경에서의 지화학 특성을 규명하기 위하여 각종 이온지질온도계와 다성분 지질온도계를 적용하였으며, 동위원소특성과 함께 지화학 모델링을 통하여 심부환경에서의 온천수의 지화학특성을 밝히고자 하였다. 동래 지열수의 수리화학적 특성은 해수의 영향을 받아 높은 이온함량을 보이며 Na-Cl형을 보여준다. 지열수는 주변 지하수와의 크게 혼합된 양상을 나타낸다. 지화학 모델링에 따르면 지열수는 심부에서 약 5% 영향을 받은 것으로 추정된다. 즉, 심부로 순환하는 지열수가 해수와 혼합되며, 이들이 지열에 의해 가열되면서 광물의 용해 및 침전, 이온 교환반응 등 물-암석 반응을 거치면서 심부지열수를 형성하였으며, 지열수가 천부환경으로 상승하는 과정에서 동래지역 주변 천부지하수와 다양하게 혼합되면서 현재 동래온천수의 화학조성을 갖는 온천수를 형성하는 것으로 지열수의 진화 과정을 설명할 수 있다.

• Journal of Aquaculture
• /
• v.13 no.2
• /
• pp.137-145
• /
• 2000

Capacity of water treatment of the three phase fluidized bed reactor as a biofilter in the seawater recirculating system was evaluated. The water treatment system consists of fluidized bed reactor for ammonia removal, cartridge filter for solid removal and ozone contactor for disinfection. Mean concentration of water quality parameters: COD, TAN, $NO_2$-N, $NO_3$-N, SS and alkalinity were 9.0, 0.22, 0.05, 20.0, 9.5 and 70.0 mg/l, respectively; the relevant values were 7.6 for pH and 3.64 NTU for turbidity. These indicate the maintenance of good water quality by the treatment system. The influent TAN loading rate in to the fluidized bed reactor ranged from 4.3 to 32.9 g/$m^3$/day, and averaged to 20 g/$m^3$/day. TAN removal efficiency of each phase of the fluidized bed reactor was 47-60%, indicating the effective ammonia removal. During operation the effluent of fluidized bed reactors also maintained the unionized ammonia nitrogen level below 0.002 mg/l.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.451-454
• /
• 2011

Hydro-Reactive metal Fuel (HRF) which has more fuel than general solid propellant reducing oxidizing agent is suitable for ultrahigh speed rocket motor in the water. However, burning rate of HRF has not been studied yet. Through the earlier studies, we established ultrasonics measurement system measuring burning rate of solid propellant as a function of pressure in a single test and verified its reliability. In this paper, we will measure burning rate of HRF using ultrasound with previous development measurement system.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.6 no.3
• /
• pp.309-325
• /
• 1994

Ocean circulation in the Gulf of Alaska is remarkably constant throughout the year despite of being forced by one of the largest seasonal wind stresses in the world. To explain the small seasonal changes in the transport of Alaska Stream. a set of numerical models is employed. First a diagnostic approach is applied to reproduce circulation from the observed density structure. The results reveals the very small seasonal changes in the Alaska Stream transport. Next a series of the prognostic models is used: a barotropic model. a flat bottom baroclinic model, and baroclinic model with topography. These models reveal the influence of topography and baroclinicity on the ocean's response to the seasonal wind forcing. The intercomparisons of the various model results suggest that the seasonal response of the baroclinic ocean is primary barotropic and the resultant barotropic circulation is weakened by the scattering effect of the bottom topography.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.3
• /
• pp.310-316
• /
• 1999

Physiological responses (cortisol, glucose, GPT, GOT, total protein, hematocrit, sodium, chloride, potassium, total calcium and osmolality), growth and survival rates of grey mullet (Mugil cephalus) and Nile tilapia (Oreochromis niloticus) by the manipulation of salinity were studied. Salinity was increased directly from freshwater to $33\%_{\circ}$ and remained for 15 days. Then, salinity was decreased directly from seawater to freshwater and remained for other 15 days. All tilapias were dead at the third day, but $96.5\%$ of grey mullet were survived at the 30th day. The grey mullet showed no significant differences for cortisol and glucose concentrations in the seawater and freshwater. However, those of the Nile tilapia were increased in seawater. The grey mullet showed no significant differences for sodium, chloride and potassium concentrations during experimental period. However, those of the Nile tilapia were significantly increased when exposed to seawater. The osmolality of grey mullet ranged between 293.5 mOsm/kg and 335.0 mOsm/kg for the whole experimental period.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2001.10a
• /
• pp.219-220
• /
• 2001

연안퇴적물로 유입되는 유기물은 수중과 해수/퇴적물 계면에서 다양한 생지화학적 반응을 거치면서 재순환되며 일부는 퇴적물로 제거된다. 본 연구는 가막만에서 해역의 특성을 반영하는 대표적 환경인 소호지역, 굴양식장, 어류 양식장 그리고 비교적 교란이 없으리라고 생각되는 지역을 선정하여 이 지역 상부퇴적물에서 일어나는 유기탄소와 암모니아 질소, 인산인의 생지화학적 순환 및 각 성분의 플럭스를 추정하고자 한다. (중략)