Hot-press forming(HPF) steel can be applied successfully to auto parts because of its superior mechanical properties. However, its resistances to aqueous corrosion and the subsequent hydrogen embrittlement(HE) decrease significantly when the steel is exposed to corrosive environments. Considering that the resistances are greatly dependent on the properties of coating materials formed on the steel surface, the characteristics of the corrosion and hydrogen diffusion behaviors regarding the types of coating material should be clearly understood. Electrochemical polarization and impedance measurements reveal a higher corrosion potential and polarization resistance and a lower corrosion current of the Al-coating compared with Zn-coating. Furthermore, it was expected that the diffusion kinetics of the hydrogen atoms would be much slower in the Al-coating, and this would be due mainly to the much lower diffusion coefficient of hydrogen in the Al-coating with a face-centered cubic structure. The superior surface inhibiting effect of the Al-coating, however, is degraded by the formation of local cracks in the coated layer under severe stress conditions, and therefore further study will be necessary to gain a clearer understanding of the effect of cracks formed on the coated layer on the subsequent corrosion and hydrogen diffusion behaviors.

Hydrothermal synthesis of highly crystalline TiO2 nanorods is a well-developed technique and the nanorods have been widely used as the template for growth of various core-shell nanorod structures. Magneli/CdS core-shell nanorod structures are fabricated for the photoelectrochemical cell (PEC) electrode to achieve enhanced carrier transport along the metallic magneli phase nanorod template. However, the long and thin TiO2 nanorods may form a high resistance path to the electrons transferred from the CdS layer. TiO2 nanorods synthesized are reduced to magneli phases, TixO2x-1, by heat treatment in a hydrogen environment. Two types of magneli phase nanorods of Ti4O7 and Ti3O5 are synthesized. Structural morphology and X-ray diffraction analyses are carried out. CdS nano-films are deposited on the magneli nanorods for the main light absorption layer to form a photoanode, and the PEC performance is measured under simulated sunlight irradiation and compared with the conventional TiO2/CdS core-shell nanorod electrode. A higher photocurrent is observed from the stand-alone Ti3O5/CdS coreshell nanorod structure in which the nanorods are grown on both sides of the seed layer.

With increasing concerns of organic micropollutants, which are not removed by conventional wastewater treatment process, advanced oxidation processes (AOPs) are recently introduced. Among AOPs, electrochemical advanced oxidation processes (EAOPs) have advantages of simple operation and reasonable costs for construction and maintenance. However, low diffusion rate of pollutants from solution to electrode is regarded as a limitation. In this study, hollow fiber type of carbon nanotube (CHF) was fabricated and operated with flow through system to enhance mass transfer rate. The removal efficiency of BPA was achieved in following order: flow through, cross-flow, and batch methods. In addition, rate of removal in flow through system was significantly enhanced, comparing that of cross-flow operation.

Saline water electrolysis is a representative electrochemical conversion to produce chlorine gas and sodium hydroxide as major products by applying electric power. Perfluorinated sulfonic acid (PFSA) ionomers have been usually used as polymer electrolyte membrane materials owing to high sodium ion selectivity and strong resistance to acidic compounds (e.g., Cl2, HCl and so on) produced in anode. However, PFSA ionomers have been suffering from chemical degradation occurring when exposed under harsh basic condition in cathode. In this study, double layered chlor-alkali membranes were prepared by anchoring crosslinked hydrocarbon ionomer via radical polymerization technique in water channels located in a surface layer of PFSA ionomer membranes and electrochemically evaluated.

Perfluorinated sulfonic acid (PFSA) ionomers have been widely used as representative polymer electrolyte membrane (PEM) materials for water electrolysis to generate hydrogen and oxygen gases with a high purity (e.g., 99.999%) simultaneously. PEM should satisfy high selectivity of proton to water and act as gas barrier to hydrogen and oxygen in order to improve current efficiency which is a barometer to determine how effectively the electric energy is used for water electrolysis. In this study, PFSA ionomers with different chemical architectures and equivalent weights were used to make PEM materials for water electrolysis. The structure-property-performance relationship was systematically investigated.

In the present study, the impact of RO polyamide layer by long-term chemical exposure was evaluated. Basic cleaning chemicals such as NaOH increased the pure water flux and salt passage of RO membrane up to 1.6 times and 2 times, respectively. In contrast, membranes exposed to acidic chemicals such as HCl have experienced no discernible change of permeability, which indicated that basic chemicals caused the more serious damage to RO polymeric layers. However, XPS analysis showed that both membranes were experienced significant damages on cross-linking of polyamide structures. It can be concluded that basic cleaning chemicals induced the enlarged pore structure due to electrostatic repulsion between damaged polymers, while acidic chemicals caused less performance deterioration by shrinkage of the polyamide structure.

We report on the fabrication and photoelectrochemical(PEC) properties of a Cu2O thin film/ZnO nanorod array oxide p-n heterojunction structure with ZnO nanorods embedded in Cu2O thin film as an efficient photoelectrode for solardriven water splitting. A vertically oriented n-type ZnO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type Cu2O thin film was directly electrodeposited onto the vertically oriented ZnO nanorods array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were characterized using X-ray diffraction and scanning electron microscopy as well as Raman scattering. The PEC properties of the fabricated Cu2O/ZnO p-n heterojunction photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/ZnO photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., 0.77 mA/cm2 at 0.5 V vs Hg/HgCl2 in a 1 mM Na2SO4 electrolyte, revealing an effective operation of the oxide heterostructure. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Hg/ HgCl2, which made the device self-powered. The observed PEC performance was attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential, including the light absorption and separation processes of photoinduced charge carriers.

녹말은 그들이 가지고 있는 여러가지 단점들 때문에 식품산업에서 그 사용이 매우 제한적인데, 그것을 극복하기 위해 녹말을 변성 시키는 다양한 방법들이 연구되고 있다. 하지만 가장 일반적으로 사용되었던 화학적 변성 녹말은 최근 소비자들의 친환경적인 제품에 대한 선호도와 건강에 대한 관심이 높아지면서 지양되는 추세이다. 그래서 식품 회사들은 물리적 변성 녹말과 같은 Clean starch를 추구하고 있다. 팽윤, 동결, 건조는 일반적으로 식품 가공에 사용되는 처리 과정인데, 그들은 녹말의 물리화학적 특성을 변화시킬 수 있고, 결과적으로 물리적 변성 녹말을 만들 수 있을 것으로 기대된다. 그래서 본 연구의 목적은 팽윤, 동결, 건조 과정을 거쳐 물리적 변성 녹말을 제조하고 그들의 물리화학적 특성을 조사하는데 있다. 옥수수 녹말을 두 온도(30℃, 60℃)에서 팽윤 시킨 후, 두가지 동결 속도(급속 동결과 완만 동결)로 처리하였다. 위와 같은 방법으로 팽윤 정도와 동결 속도를 다르게 처리한 후, 열풍건조, 동결건조, 분무건조 세가지 방법을 통해 건조하여 물리화학적 특성들을 분석하였다. 광학·편광 현미경을 통해 형태학적 특성을 조사하였고, 시차주사열량법(DSC)과 신속점도측정기(RVA)를 이용해 열적 특성과 페이스팅 점도특성을 각각 조사하였다. 팽윤 직후 현미경 사진에서는 60℃ 팽윤처리구가 물을 흡수하며 팽창되어서 유의적으로 과립 크기가 커졌음을 확인하였지만, 모든 처리가 끝난 후 현미경 사진에서는 모든 처리구들에서 유의적인 차이를 보이지 않았다. 이는 동결·건조 되면서 물이 빠져나가 다시 녹말 과립이 수축되어 다시 원래의 크기로 돌아간 것으로 생각된다. 하지만 DSC 결과에서 팽윤·동결처리를 하였을 시 대조구보다 호화개시온도(To), 최대호화온도(Tp)가 낮아졌으며, 30도 팽윤처리구와 완만동결처리구에서 특히 유의적인 차이를 보였다. RVA 결과에서 최대 점도와 breakdown이 대조구보다 유의적으로 변하였으며, 특히 급속동결처리구와 30도 팽윤처리구에서 유의적인 변화를 보였다. 열풍건조와 분무건조는 대조구에 비해 큰 변화를 가져오지 못하였으며, 동결건조는 DSC나 RVA결과에서 큰 변화를 가져왔다. 그러므로 팽윤, 동결, 건조는 녹말의 물리화학적 특성을 변화 시킬 수 있고, 녹말의 변성 방법으로서의 이용가능성을 제시하였다.

호화 된 전분은 무정형 구조이지만 시간이 지남에 따라 전분 분자들 간의 재결합으로 인해 결정형 구조를 갖게 되며, 이 현상을 노화라고 한다. 전분의 노화는 전분의 소화도와 텍스쳐의 품질을 낮춤으로서 전분질 식품에 대한 소비자의 기호도를 떨어뜨린다. 이러한 전분질 식품의 노화를 지연시키는 방법으로는 화학적 노화억제제 또는 효소 첨가가 대표적이다. 유화제와 가소화제, 또는 효소를 단독으로 사용한 문헌은 많지만, 효소와 첨가제를 동시에 사용하여 노화에 대한 복합적인 효과를 알아본 연구는 미미하다. 본 연구에서는 화학적 노화억제제와 효소를 첨가한 가래떡을 제조하였고, 저장기간 동안 노화 된 가래떡의 물리화학적 특성을 알아보았다. 연구에서 화학적 노화억제제는 자당지방산에스테르(SE)와 글리세롤(Gly)을 사용하였으며, 효소는 내열성 α-amylase인 Termamyl (TER)과 glucoamylase인 AMG를 사용하였다. 각각의 첨가제와 효소의 양은 예비실험을 통해 선정하였고 SE와 Gly, TER은 Steam 전, AMG는 Steam 후 첨가 해 주었다. 습식제분 멥쌀가루를 사용하여 수분함량이 45%가 되도록 반죽하였고, 아무것도 첨가하지 않은 가래떡을 대조군으로 하였다. 제조 된 떡은 진공포장 후 상온에서 저장하였으며 물리화학적 특성을 경도분석기, 시차열량주사기(DSC)로 분석하였다. 경도에서 모든 샘플 떡이 저장초기 대조군 보다 낮음을 보였다. SE와 AMG를 함께 넣은 샘플은 SE와 AMG를 단독으로 사용 했을 때 보다 경도를 낮추는데 효과적이었으며 다른 샘플들이 저장초기에만 노화 지연 효과를 보인 것에 반해, 저장 9일차 동안 노화에 영향을 미쳤다. DSC 결과에서, 글리세롤을 단독으로 첨가한 떡뿐 만 아니라 TER을 함께 첨가한 떡의 유리전이 온도(Tg’)는 대조군 보다 낮은 값을 보였으며 이를 통해 두 가지를 동시에 첨가했을 경우 역시 가소화 효과가 일어났음을 알 수 있다. 또한, AMG가 단독으로 또는 노화억제제와 함께 첨가 된 모든 떡의 경우 Tg’가 대조군과 다르게 감소하였으며 얼음용융엔탈피(ΔHi)에서도 대조군과는 다르게 3일차 까지는 증가하였다가 그 이후부터 감소함을 보였다. 이러한 AMG의 Tg’와 ΔHi특성은 glucoamylase의 활성으로 생성된 환원당과 그로 인한 빙점강하가 저장 초기에 우세하게 작용하였지만, 저장 후기에서 전분 분자들의 재결정화가 우세해 지면서 다음과 같은 경향을 띤 것으로 보여진다. 아밀로펙틴용융엔탈피(ΔHr)의 경우 모든 샘플이 대조군 보다 낮은 엔탈피가 나타났으며, 이를 통해 전분의 재결정이 지연되었음을 알 수 있다. 본 연구 결과를 바탕으로 전분 노화에 대한 효소와 노화억제제 간의 복합적인 효과를 밝히는데 도움이 될 것이라 생각된다.

Phosphorus (P) is a limited, essential, and irreplaceable nutrient for the biological activity of all the living organisms. Sewage sludge ash (SSA) is one of the most important secondary P resources due to its high P content. The SSA has been intensively investigated to recover P by wet chemicals (acid or alkali). Even though H2SO4 was mainly used to extract P because of its low cost and accessibility, the formation of CaSO4 (gypsum) hinders its use. Heavy metals in the SSA also cause a significant problem in P recovery since fertilizer needs to meet government standards for human health. Therefore, P recovery process with selective heavy metal removal needs to be developed. In this paper some of the most advanced P recovery processes have been introduced and discussed their technical characteristics. The results showed that further research is needed to identify the chemical mechanisms of P transformation in the recovery process and to increase P recovery efficiency and the yields.

In this study, we investigated the nutritional composition including proximate, amino acid, vitamin, minerals, and the antioxidant activity of green tea (Camellia sinensis) pollen grains collected by Apis mellifera bees, for use as a health food. The crude protein and fat content was estimated at 26.14% and 3.49%, respectively. Eighteen amino acids were identified in green tea pollen, including 8 essential amino acids and 10 non-essential amino acids. The predominant amino acids were glutamic acid, proline and aspartic acid accounting for about 33.3% of total free amino acids. The concentration of vitamin C was the highest value of 35.7%, followed by B3 and B2 among the detected vitamins. The predominant minerals were potassium (790.32 mg/100g), followed by phosphorus (707.52 mg/100g) and sulfur (302.67 mg/100g), whereas copper, zinc and sodium were detected as minor elements. The antioxidant activity and phenolic content accounted for 33.8% at 500 μg/mL extract and 2.55 μg/mg, respectively.

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.

Various carbon aerogels (CAs) were prepared from polymerization of resorcinol and formaldehyde and applied as the electrode materials of an electric double layer capacitor (EDLC) with the aim of controlling the textural and electrochemical properties of CAs by the type of base catalyst and the ratio of resorcinol to catalyst (R/C). The CAs from NaHCO3 and KHCO3 with H+ ions had higher specific surface areas but exhibited lower electrochemical properties than those from K2CO3 and Na2CO3, which had more uniform pore size distributions. The electrochemical properties of Na2CO3 were superior to those of K2CO3 probably because the polarizing power of Na+ ions was higher than K+ ions. With an increasing R/C ratio, the pore sizes of CA showed a tendency to increase but the uniformity of the pore size distribution got worse. For the four base catalysts, the highest electrochemical property was obtained at the R/C ratio of 500.

For the purpose of developing new immunomodulatory agents from broccoli, ethanol extract (BCEE), hot water extract (BCHW), and crude polysaccharide (BCCP) were isolated from broccoli, and their immunomodulatory activities and chemical properties were examined. In the in vitro cytotoxicity analysis, BCHW and BCCP did not affect the growth of tumor cells and normal cells. Murine peritoneal macrophages stimulated with BCCP showed higher production of IL-6, IL-12, and TNF- α cytokines than those stimulated with BCHW. Also, BCHW and BCCP did not show proliferation of splenic lymphocytes. In the in vitro assay for intestinal immunomodulatory activities, only BCCP enhanced GM-CSF secretion and the bone marrow cell-proliferating activity via cells in Peyer’s patches at 1,000 μg/mL. Also, BCHW mainly contained 33.7% neutral sugars, such as arabinose, glucose, and galactose, and 30.7% uronic acid, and BCCP consisted of 42.6% neutral sugars, including arabinose, galactose, and glucose, and 50.5% uronic acid. The above results lead us to conclude that crude polysaccharide (BCCP) isolated from broccoli causes considerably high cytokine production in peritoneal macrophages and bone marrow cell proliferation, and the polysaccharide extraction process is indispensable for separation of new immunomodulatory agents from broccoli.

가소제는 딱딱한 특성을 지닌 플라스틱에 유연성 및 탄성을 주어 제품으로서의 부드러운 특성을 갖출 수 있도록 첨가되는 물질로서, 주로 고분자 물질에 첨가되어 유연성을 부여함으로써 가공성을 개선하 고, 내한성, 내휘발성, 전기적 특성을 강화할 목적으로 이용되고 있다. 대부분의 가소제는 비활성 액체로서 용매의 기능과 유사한 역할을 하지만 분자량이 크고 휘발성이 없다. 또한, 석유화학제품에 용해되어 있는 경우, 다른 화합물과의 중첩효과(matrix effect)에 의해 가소제만을 분리하여 정성 및 정량분석하기에 어려움이 있다. 본 연구에서는 석유화학제품에서 검출될 수 있는 가소제의 대표적 성분인 DOA와 DOP에 대해 MD-GC/MS를 활용하여 정성 및 정량분석을 실시하여 최적의 가소제 분석 방법을 개발하고자 하였다.

해상 HNS 유출사고 대응 교육훈련체계의 국내 및 외국(미국, 캐나다, 호주, 영국) 현황을 살펴보고, 국내 체계와 외국 체계 간의 비교를 통하여 국내의 교육훈련체계 개선방안에 대한 연구를 수행하였다. 그 결과, 국내의 민간 교육훈련기관이 거의 전무한 상태에서 외 국의 기관들에 비하여 활성화되지 못하였고, 국내의 해상 HNS 관련 교육훈련이 정부 주도 하에 획일적으로 이루어지고 있는 실정이었다. 또한 국내의 교육훈련기관인 해양경찰교육원과 해양환경교육원 간에는 교육대상자, 교육기간 등에서 차이가 있었다. 국내의 해상 HNS 관 련 교육과정이 외국의 교육과정에 비하여 단순한 편이었고, 교육기간도 상대적으로 짧았으며, 국제해사기구 HNS 모델코스의 2가지 과정(운 영 수준 및 관리자 수준)을 수용하지 않고 있었다. 국내 해상화학사고 대응 교육훈련체계를 개선하기 위한 방안을 단기적 측면과 중 장기 적 측면으로 나누어 제시하였다. 단기적 측면에서, 해양경찰교육원과 해양환경교육원은 각자 독립적으로 운영하는 현행의 이원적 체계를 유지하면서 두 기관이 공동으로 참여하는 HNS교육훈련운영협의체(가칭)를 설립하는 방안을 제시하였고, 중 장기적 측면에서는, 해양경찰 교육원 HNS 담당부서와 해양환경교육원 HNS 담당부서를 통합하여 국제경쟁력을 갖춘 일원적 체계인 국가해상HNS방제교육훈련기관(가칭) 으로 변경 확대하는 방안을 제시하였다.

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of 2.13 kgf/cm2, but it was recovered to the initial level (0.17 kgf/cm2) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.

This study was carried out to obtain the basic quality characteristics, like moisture contents, hunter color value, total polyphenol, starch, amylose, and ash contents and pasting characteristics of sweet potato cultivars according to storage periods. Moisture contents of all the varieties decreased with long storage period, and were lower in dry type than tender and moist type sweet potato. Lightness(L value) of sweet potato flesh was decreased in Shinyulmi, Daeyumi, Shinhwangmi but other seven cultivars showed increasing trend. Redness(a value) was increased in Sinyulmi, Sinhwangmi, Sinjami and yellowness (b value) increased in Yeonjami only. The total polyphenol contents increased in Dahomi, Sinjami up to 4 months of storage and all other varieties showed decrease during storage period. The starch contents also decreased with storage period. The amylose contents showed different by the cultivars. The ash contents in all varieties ranged from 1.1 to 1.7%, and there was no difference among varieties and storage periods. There was no change in pasting temperature during storage periods. Peak viscosity, through viscosity, breakdown and final viscosity were different according to storage periods and cultivars. But setback tended to increase in all cultivars.

In this study, the surface passivation process for InP-based quantum dots (QDs) is investigated. Surface coating is performed with poly(methylmethacrylate) (PMMA) and thioglycolic acid. The quantum yield (QY) of a PMMA-coated sample slightly increases by approximately 1.3% relative to that of the as-synthesized InP/ZnS QDs. The QYs of the uncoated and PMMA-coated samples drastically decrease after 16 days because of the high defect state density of the InP-based QDs. PMMA does not have a significant effect on the defect passivation. Thioglycolic acid is investigated in this study for the effective surface passivation of InP-based QDs. Surface passivation with thioglycolic acid is more effective than that with the PMMA coating, and the QY increases from 1.7% to 11.3%. ZnS formed on the surface of the InP QDs and S in thioglycolic acid show strong bonding property. Additionally, the QY is further increased up to 21.0% by the photochemical reaction. Electron–hole pairs are formed by light irradiation and lead to strong bonding between the inorganic and thioglycolic acid sulfur. The surface of the InP core QDs, which does not emit light, is passivated by the irradiated light and emits green light after the photochemical reaction.