• Journal of Adhesion and Interface
• /
• v.22 no.2
• /
• pp.47-56
• /
• 2021

Steel plates coated by self-healable polymer still can be rusted since it takes time to be healed. In this study, dual self-healing coating material is developed using corrosion inhibitor (DTBEDA) which can form hindered urea (HUB) as reversible cross-linking bond at the same time. Developed dual self-healing polymer is coated on steel plate, and scratch healing property was investigated by surgical blades and nano/micro indentation tester. The anticorrosion effect of DTBEDA was investigated by electrochemical impedance spectroscopy (EIS).

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.309-309
• /
• 2014

음극방식법은 피방식체에 외부전원을 인가하거나 보다 활성인 금속을 전기적으로 연결하여 피방식체의 전위가 일정 전위까지 음극분극 되도록 하여 부식을 억제하는 방법이다. 이러한 음극 방식의 결과로 $OH^-$이온이 금속 표면 부근에 생성되고 금속/해수 사이의 pH 증가를 유발하게 되며, 높은 pH는 $Mg(OH)_2$ 및 $CaCO_3$의 석출을 유발한다. 전착 박막은 각각 1, 3, 6, 12시간 및 5, 15, $20mA/cm^2$의 전류 밀도 조건에서 자연 해수, $CO_2$ 가스가 용해된 해수 용액 내에서 스틸 기판 상에 전기적 증착기술을 가해 형성되었다. 상기 조건에서 증착 된 박막의 내용물은 주사 전자 현미경 (SEM) 및 X-선회절(XRD)에 의해 조사되었다. 또한 코팅 박막의 내식성은 전기화학적 양극 분극시험에 의해 평가되었다.

• Journal of the Korean Chemical Society
• /
• v.32 no.4
• /
• pp.377-384
• /
• 1988

Carotenoprotein from Salmo Salar eggs was purified and characterized by CM-cellulose, 50% $(NH_4)_2SO_4$, DEAE-cellulose and sephadex G-75 column. The chromoprotein had a spectrum with ${\lambda}_{max}$ 409, 540 and 580nm in p-buffer (pH 7.0) at initial step. Molecular weights by sephadex G-200 gel filtration were 50, 200 and 26,000 daltons. SDS-PAGE analysis showed a structure with four identical subunits (12,500 daltons). Its sample retained a small amount of carbohydrates and lipids. Amino acids were analyzed, and mannose, galactose and glucosamine also were identified. Carotenoid extacted with acetone was found to be astaxanthin ester by partition test, epoxy test, iodine test, allylic test, reduction, acetylation, uv/vis, ir and nmr datas. Stearate (47.9%) and palmitate (21.4%) were predominant fatty acids in the astaxanthin ester.

• Journal of the Korean Chemical Society
• /
• v.7 no.4
• /
• pp.251-253
• /
• 1963

Six corrosion inhibitors for cooling water use were evaluated by means of a corrosometer in a laboratory bench scale test. A steel probe (Alloy 1020) was exposed and checked for the extent of corrosion in a recirculating water system, changing inhibitors and their concentrations at $40^{\circ}C$. A 95% inhibition was provided at the following concentrations of inhibitors. 50 ppm sodium hexametaphosphate 50 ppm commercial inhibitor A 50 ppm commercial inhibitor B 100 ppm disodium phosphate 200 ppm sodium chromate Sodium silicate was found to be use-less in this test. It was also observed that some inhibitors worked less effectively on the acid-cleaned steel probe.

• Journal of the Korean institute of surface engineering
• /
• v.39 no.1
• /
• pp.18-24
• /
• 2006

Although stainless steels have the excellent corrosion resistance by passive film, they are susceptible to pitting corrosion in the environment containing halogen elements such as chloride ions. The resistance to pitting corrosion can be evaluated by measuring the critical pitting temperature (CPT). CPT values can be obtained using immersion, potentiodynamic and potentiostatic polarization test methods. Results on duplex 2205 stainless steels showed that CPT values were measured as $50^{\circ}C,\;55^{\circ}C\;and\;61^{\circ}C$, respectively for immersion, potentiodynamic and potentiostatic polarization test methods, depending upon the different test methods, even though the difference between CPT values are not much.

• Journal of the Korean Electrochemical Society
• /
• v.11 no.4
• /
• pp.289-296
• /
• 2008

Electrochemical studies were performed by a half-cell test for the nickel hydroxide (cathode) and hydrogen storage alloy(anode) electrodes for the sealed Ni-MH batteries applicable to industrial use. The electrodes were fabricated and checked a charge efficiency and an internal pressure of the battery during charge-discharge cycling. In order to reduce the internal pressure of the sealed Ni-MH battery, cyclic voltammetry (CV) were performed on the electrodes of nickel hydroxide(cathode) and hydrogen storage alloy(anode), respectively. The results of the test showed clearly the oxidation/reduction and oxygen evolution reaction in a nickel hydroxide electrode and the hydrogenation behavior of a hydrogen storage electrode. The sealed Ni-MH battery of 130Ah was fabricated by using nickel hydroxide of a high over-voltage for an oxygen gas evolution and hydrogen storage alloy of a good performance for activation The battery showed a good characteristics such as a high charge efficiency of 98% at 1 C charge current, a low level internal pressure of 4 atm on a continuous over-charging and a large preservation capacity of 95% at 400 cycle.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.4
• /
• pp.417-424
• /
• 1987

The seeds of three barley varieties of which initial seed vigor were different were used to measure seed vigor of accelerated aging techniques. A vigor index derived from the product of percent germination and plumule length was used to estimate seed vigor. The index was compared with the results of other tests. The results of warm germination test well suited to the measurements of seed vigor at the advanced stages of seed deterioration. Other vigor measurements except ATP and GADA values, showed close relationships with the vigor index. The measurements of plumule length in cold test and tetrazolium test were found to be appropriate for predicting seed quality.

• Applied Chemistry for Engineering
• /
• v.30 no.6
• /
• pp.659-666
• /
• 2019

Proton exchange membrane fuel cells (PEMFCs) generate electricity by electrochemical reactions of hydrogen and oxygen. PEMFCs are expected to alternate electric power generator using fossil fuels with various advantages of high power density, low operating temperature, and environmental-friendly products. PEMFCs have widely been used in a number of applications such as fuel cell vehicles (FCVs) and stationary fuel cell systems. However, there are remaining technical issues, particularly the long-term durability of each part of fuel cells. Degradation of a carbon supported-platinum catalyst in the anode and cathode follows various mechanistic origins in different fuel cell operating conditions, and thus accelerated stress test (AST) is suggested to evaluate the durability of electrocatalyst. In this article, comparable protocols of the AST durability test are intensively explained.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.3
• /
• pp.593-598
• /
• 2016

We report on the preparation of reduced graphene oxide (rGO)/single-walled carbon nanotubes (SWNTs) electrodes deposited onto flexible polyethylene terephthalate (PET) via spray coating technique. The highest capacitance value of the unbent rGO/SWNTs electrode was $82Fg^{-1}$ in 1 M $H_2SO_4$ at $100mVs^{-1}$, which decreased to $38Fg^{-1}$ after 500 bending cycle. Further characterization, including galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy (EIS), showed that the rGO/SWNTs electrode retained a well-defined capacitive response after repetitive bending cycle. Overall, the rGO/SWNTs composite electrode showed reasonable electrochemical properties even prolonged bending cycle. Approximately 50% of the initial capacitance for the rGO/SWNTs composite electrode is remained after 500 bending cycle, making the electrode a potential option for flexible energy storage applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.6
• /
• pp.104-108
• /
• 2009

The insulation aging characteristics and structural analysis test were performed to analyze the correlations among the insulation deterioration, diagnostic results and the breakdown strength for the underground power cables. From the results of the degree of crosslinking test, hot-oil test etc., it could be confirmed that there were no manufacturing defects in the power cables under test. From the results of the water tree test and chemical structural analysis, it could be confirmed that the aging status of cable under test were very poor, especially for B-Phase and the degree of aging was increased in the orders of A, C and B-phase. From the above results, it could be concluded that the insulation aging characteristic analysis results were well consistent with the diagnostic and breakdown test results, and also confirmed that the diagnostic system under consideration was successful to discriminate the bad cables which is likely to cause cable system failure.