Quantitative estimation of reversibility of the discharge process undergone by nickel hydroxide film cathodically deposited on pure nickel as a positive supercapacitor electrode using cyclic voltammetry and potential drop method

Pyun Su-Il,Moon Sung-Mo The Korean Electrochemical Society 1998 한국전기화학회지 Vol.1 No.1

This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.

Colloidal fouling in forward osmosis: Role of reverse salt diffusion

Boo, C.,Lee, S.,Elimelech, M.,Meng, Z.,Hong, S. Elsevier Scientific Pub. Co 2012 Journal of membrane science Vol.390 No.-

Colloidal fouling behavior in forward osmosis (FO) was investigated, focusing on the role of reverse salt diffusion. Two suspensions of silica nanoparticles, with average particle diameters of 24 and 139nm, were used as model colloidal foulants. To verify the effect of reverse salt diffusion on the colloidal fouling behavior, NaCl and LaCl<SUB>3</SUB> were employed as draw solutions because they exhibit different reverse diffusion rates. Our results suggest that in colloidal fouling of FO, salts diffuse from the draw to the feed solution and accumulate within the colloidal fouling layer that forms on the membrane surface. The accumulated salts result in a marked acceleration of cake-enhanced osmotic pressure (CEOP), which reduces the net osmotic driving force for permeate water flux. Fouling was not observed with the small, 24-nm particles because of the lack of substantial cake formation, but was notable for the 139-nm particles and for a feed containing a mixture of the 24 and 139nm particles. Our findings further indicate that colloidal fouling is enhanced under solution conditions (ionic strength and pH) within the colloidal cake layer that promote aggregation or destabilization of the silica particles. Colloidal fouling reversibility was also examined by varying the cross-flow velocity during the FO fouling runs. We showed that in the absence of colloidal particle destabilization/aggregation, the permeate flux during colloidal fouling in FO recovered almost completely when the cross-flow velocity was increased from 8.5 to 25.6cm/s. Our results suggest that reverse salt diffusion in FO is a key mechanism that controls colloidal fouling behavior as well as fouling reversibility. Therefore, minimization of reverse salt diffusion through the selection of proper draw solutes and optimization of FO membrane selectivity are important for minimizing colloidal fouling as well as enhancing FO operation efficiency.

Fabrication of a cerium-doped nickel ferrite solid-state reference electrode and its performance evaluation in concrete environment

Subbiah, Karthick,Han-Seung, Lee,Yun Su, Lee,Jitendra Kumar, Singh,Seung-Jun, Kwon,Rethinam, Natarajan Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.251 No.-

<P><B>Abstract</B></P> <P>In this study, we fabricated a solid-state reference electrode (SSRE) using cerium (Ce) doping in nickel ferrite (NiFe<SUB>2</SUB>O<SUB>4</SUB>) nanoparticles (NPs) to monitor the corrosion of steel rebar in concrete. The process for synthesis of NPs was sol-gel combustion. The NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) probed with energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). These techniques confirmed that the Ce doping was achieved successfully. The electrochemical stability of the fabricated SSRE was studied in buffer solution at different pH (7, 9, and 12) as well as in synthetic concrete pore solution (SCPS) and 3% NaCl-contaminated SCPS. Chloride ions do not affect the property of Ce<B>-</B>doped NiFe<SUB>2</SUB>O<SUB>4</SUB>. The stability of Ce-doped SSREs in different solutions as well as in concrete was constant throughout the exposure periods. The reversibility test results of Ce<B>-</B>doped NiFe<SUB>2</SUB>O<SUB>4</SUB> in SCPS solution for NiCe<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O<SUB>4</SUB> (NFC1) and NiCe<SUB>0.5</SUB>Fe<SUB>1.5</SUB>O<SUB>4</SUB> (NFC5) showed 20 and 15mV, respective differences in potential between the forward and reverse scan. This result indicates that Ce<B>-</B>doped NiFe<SUB>2</SUB>O<SUB>4</SUB> SSREs have better reversibility behavior than NiFe<SUB>2</SUB>O<SUB>4</SUB> in SCPS. The reliability of NFC5 SSRE is excellent in SCPS and a concrete environment, and the maximum difference in both conditions was 5mV, which is within the range of acceptable values. This indicates that Ce<B>-</B>doped NiFe<SUB>2</SUB>O<SUB>4</SUB> SSRE can be used as a reliable embeddable sensor in concrete structures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ce doped nickel ferrite was developed as a novel solid state reference electrode. </LI> <LI> Doping of Ce in nickel ferrite was successfully achieved. </LI> <LI> Stability of fabricated SSREs was studied in different pH solutions. </LI> <LI> Fabricated Ce doped SSREs attributed strong stability and high reversibility. </LI> </UL> </P>

Critical flux-based membrane fouling control of forward osmosis: Behavior, sustainability, and reversibility

Nguyen, Thanh-Tin,Kook, Seungho,Lee, Chulmin,Field, Robert W.,Kim, In S. Elsevier 2019 Journal of membrane science Vol.570 No.-

<P><B>Abstract</B></P> <P>Membrane fouling is closely related to the concept of critical flux. Therefore, a fouling control strategy for forward osmosis (FO) membranes that is based on the critical flux is necessary. This study systematically investigated the critical flux behavior of FO membranes (CTA and PA-TFC) in the short-term using a stepping method (draw solution (DS) concentration stepping). In addition, to test the reliability of this method, long-term experiments were conducted to evaluate the influences of operational critical flux on the fouling behavior (sustainable operation and fouling reversibility/irreversibility), thereby determining the critical flux for reversibility. Our results showed that the DS concentration stepping could be applied for critical flux determination in FO. Both membranes exhibited higher critical flux values for alginate fouling compared to other single foulants such as colloidal silica or gypsum. The values were 15.9 LMH for a cellulose triacetate membrane (CTA) and 20.5 LMH for the polyamide thin-film composite (PA-TFC). Whilst these values should be adequate in FO applications they were determined for single foulants. The presence of multispecies of foulants caused a significant decline in the critical flux values. This study found 5.4 LMH for the CTA membrane and 8.3 LMH for the PA-TFC membrane for the combined foulants of alginate + gypsum. This indicates that the critical flux behavior in FO was dependent on the foulant type and membrane type. Importantly, the high restoration of water flux was achieved with the PA-TFC membrane at an operation either close to critical flux (92–98%) or below critical flux (98–100%) (i.e., with negligible irreversible fouling). The critical fluxes for reversibility obtained in this study will aid the efficient operation of practical FO processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Draw Solution stepping method was used to determine the critical flux value. </LI> <LI> Critical flux behavior in FO was dependent on foulants and membrane types. </LI> <LI> Plant operation below the critical flux is vital for the minimization of chemical cleaning. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

붉은 강낭콩에 의한 소장점막 손상후 재생에 과한 연구

송인성(In Sung Song),노임환(Im Hwan Roe),김정룡(Chung Young Kim) 대한내과학회 1991 대한내과학회지 Vol.40 No.3

N/A Red kidney bean (RKB) has been shown to cause toxic effct such as diarrhea, weight loss and failure of growth in animal and man. To investigate the reversibility of toxic effect of RKB, male adult rats weighing 140 gm were separated into 5 groups (n=10 in each group). Control group received a basic diet ad libitum for 3 weeks. Group I received the diet that crude RKB was added for 12% of the diet and were killed 1 week later. Group II received the RKB diet for 2 weeks. Group III received the RKB diet for 2 weeks and thereafter the basic ad libitum diet for 1 week, and Group IV received the RKB diet for 2 weeks following the ad libitum diet for next 2 weeks. During the period of RKB diet, progressive weight loss was found in each group. But after returning the basic diet progressive weight gain was noticed in group III and IV. During the period of RKR diet, villous height and crypt depth were increased progressively in each group. But they were almost same as those of the control after returning the basic ad libitum diet in group III and IV. And the mucosal enzymes activities such as sucrase, lactase, aminopeptidase and alkaline phosphatase were depressed on RKB diet and returned to control level after receiving the basic ad libitum diet for Z weeks. This study indicate that the toxic effect of RKB on small intestinal mucosa was completelv reversible.

인공지능형 로봇은 얼마나 가역적일 수 있을까? - 콜버그의 도덕 발달 단계의 적용과 도덕과 교구 활용 가능성을 중심으로 -

송선영 ( Song Sun-young ) 한국윤리교육학회 2021 윤리교육연구 Vol.- No.61

이번 연구는 인공지능형 로봇을 활용하는 일상에서 도덕적 의미를 이해하고, 도덕 발달 교육에서 인공지능 로봇의 도덕과 교구의 활용 가능성을 탐색하는 것을 목적으로 한다. 이를 위해 콜버그의 정의 발달 이론에서 도덕적 상황과 면담, 역할채택과 감정이입, 끌어냄의 도덕 교육의 내용에서 인공지능형 로봇이 도덕 발달 도구로써 활용될 가능성을 도출하였다. 도덕적 딜레마에 기반한 종단 연구에서 면담의 데이터를 활용한 정의 발달 추론의 알고리즘은 조건적이지만 인공지능형 로봇이 면담자와 해석자의 역할과 학습자의 데이터 해석을 가능하게 만든다. 이런 점에서 도덕 발달 교육에 인공지능형 로봇을 활용하기 위한 가역성은 교사와 학생 간의 관계를 매개하는 인공적이고 조건적인 특징을 갖는다. 나아가 이러한 조건적 가역성은 학습자의 도덕적 성장에서 보편적 원리화 수준으로 이끌 수 있는 5단계의 발문을 포함할 필요가 있다. This paper aims to understand moral contexts in utilizing AI robots and to explore any possibility that as teaching tools they can be applied to moral classes. In Kohlberg’s theory of moral development based on moral stages of the principle of justice, AI robots of the ethical algorithm of justice can take a role between teachers and students, as artificial and conditioned interviewers as well as interviewees. With students, for example, AI robots can participate in moral discourse of dilemma to develop the principle of justice and accumulate their thoughts and judgments as digital data. At the same time, moral teachers can get more exact information on their students’ moral reasonings, control the moral stages for them, and draw into the recognition of morality (justice) by utilizing AI robots as teaching tools. This is the main character of conditioned reversibility of AI robots that enables students to be motivated to recognize the universalized principle in stage 5.

중등도 이하 근시 환자에서 역기하렌즈 착용중지 후 각막 변화 관찰

윤여민,김미금,이재림,Yie-Min Yun,Mee-Kum Kim,Jae-Lim Lee 대한안과학회 2005 대한안과학회지 Vol.46 No.9

Purpose: To investigate the recovery time associated with refractive and corneal topographic changes after discontinuing short term wear of reverse-geometry contact lenses in low and moderate myopic patients. Methods: Twenty-four eyes of 12 patients who were fitted with Ortho-K LKTM lenses for a mean duration of 7.9 months were divided into two groups based on the mean manifest refraction (MR) of -3.50D. In groups I (mean MR -2.83D) and II (mean MR -4.00D), uncorrected visual acuity, refractive correction, and topographic changes were evaluated at 3 days; 1, 2, and 3 weeks; and 1, 2, 3, and 6 months after discontinuation of lens wear. Corneal thickness was measured at its center and 3.0 mm from its center. Results: The uncorrected visual acuity, mean spherical equivalent, and average apical keratometric indices recovered at 2 weeks and 1 month after discontinuation of lens wear in groups I and II, respectively. Mean Sim K and corneal thickness recovered at 1 and 2 weeks in groups I and II, respectively. All of the recovered indices remained stable at 6 months. Conclusions: Recovery of corneal changes after short-term use of reverse-geometry lenses was achieved at 2 weeks in cases of low myopia (less than -3.50D) and at 1 month in cases of moderate myopia (more than -3.50D), with both remaining stable to the 6-month mark.

『아라비언 나이트』: ‘유혹’의 텍스트

윤민우(Minwoo Yoon) 한국영미문학교육학회 2007 영미문학교육 Vol.11 No.2

By assuming the role of storyteller in The Arabian Nights, Shahrazad translates King Shahrayar"s desire for body to the one for text. This transition is facilitated by the shared quality of "seduction." Seduction excites but never fully gratifies one"s textual and erotic desires. Shahrazad"s tales provoke curiosity and, at the same time, postpone its complete satisfaction. Seduction is, therefore, the fusion of simulation of an end and resistance to it. It is the seduction that enables Shahrazad to extend her tales for ever in a "metonymical" way. In ""the Tale of the Porter and the Three Ladies,"" the female subjects" naming their own genitalia undoes the male gazers" textualization of the female body. The discursive power of the males inscribed in the body is turned into a female narrative pleasure so that the difference in sexes is viewed as the one in language. More interestingly, by purchasing the rules of the female game, the porter, in turn, partakes of the game and produces a narrative which capitalizes on the female ludic language. Here, the porter undergoes the death of his male prerogative and accepts the "symbolic" value of the female game. This "symbolic exchange," i.e., seduction, makes a binary opposition always reversible. The Nights finally stops being a text and returns to a biological body. As a mother of three sons, Shahrazad"s body now is much less threatening than that of a slave girl or a maid. But the simultaneous cessation of the seductive body and text at the end of the Nights does not represent a "metaphorical" end, i.e., the beginning of a new paradigm, but a return to the community free from perversion and repression. Shahrazad reconciles King Shahrayar"s death instinct (Thanatos) with his life instinct (Eros). In the course of her storytelling, in fact, Shahrazad has functioned as a ""superid"" that modulates the relation between superego and id, the reality principle and the pleasure principle, and Thanatos and Eros. And this is exactly the way in which the "seduction" is meant to work.

노인환자의 기도가역성 검사에서 FEV6의 보완적 지표로서의 역할

김새희 ( Sae Hee Kim ),이양덕 ( Yang Deok Lee ),이정윤 ( Jung Yun Lee ),조용선 ( Yong Seon Cho ),나동집 ( Dong Jip Na ),한민수 ( Min Soo Han ) 대한결핵 및 호흡기학회 2006 Tuberculosis and Respiratory Diseases Vol.61 No.3

연구배경 : 기도가역성 측정시, 1초간 노력성 호기량(forced expiratory volume in one second, FEV1)과 노력성 폐활량(forced vital capacity, FVC)은 흔히 사용되는 지표인데 양성반응의 권장기준은 기저치보다 증가치가 절대량이 200㎖이상 그리고 백분율로는 12%이상의 두 조건을 다 만족하는 것이다. 그러나 노인 환자는 천식에 합당한 병력을 가지고 있어도 기도가역성의 진단기준을 만족시키지 못하는 경우가 종종 있다. 저자들은 6초간 노력성 호기량(FEV6)이 노인의 기도가역성 검사에서 역할을 알아보자고 하였다. 방법: 65세 이상의 노인환자 중 폐기능검사에서 FEV1/FVC가 80%미만인 236명에게 폐활량측정법으로 기도가역성 검사를 시행하였다. 기저 FEV1에 따라 다음과 같이 세 군으로 분류하였으며 각 군에서의 FVC, FEV6, FEV1의 지표에 따른 기도가역성을 비교 분석하였다. 제1군 : FEV1≥80%, 제2군 : FEV1 60~80%, 제3군 : FEV1≤60% 결과: 전체 환자에서 기도가역성은 각각의 지표에 따라 FEV1에서는 33명(14.0%), FEV6는 55명(23.3%), FVC는 55명(23.3%)로 양성반응을 보였고, 제3군(FEV1≤60%)에서는 FEV1을 지표로 할 때는 15명(22.4%), FEV6는 30명(44.8%), FVC는 32명(47.8%)으로 나타났다. 결론: 본 연구에서는 FEV6가 노인환자에서 기도가역성 검사의 새로운 보완적 지표로서의 역할을 보여줬지만 이의 일반화를 위해서는 좀 더 많은 연구가 필요할 것이다. Background: In the measurement of bronchodilator reversibility, the forced expiratory volume in one second(FEV1) and the forced vital capacity(FVC) are commonly used parameters and recommended criteria for the reversibility requiring an increase of more than 200㎖ and 12% above the baseline, respectively. However, aged patients do not often meet the criteria of an increase in volume(>200㎖) even though the medical history of that patient is adequate for asthma. This study investigated the role of the forced expiratory volume in six seconds(FEV6) in the bronchodilator reversibility test in elderly patients. Methods: A total of 236 patients more than 65 years of age with a FEV1/FVC ratio<80% were enrolled in this study. The bronchodilator revesibility tests were examined. With the setting FEV1 as the baseline, the patients were divided into three groups; Group I : FEV1≥80% of the predicted value, Group II : 60%<FEV1<80% of the predicted value, Group III : FEV1≥60% of the predicted value. Results: Positive reversibility in the FEV1, FEV6, and FVC was in 33(14.0%), 49(20.8%) and 55(23.3%). However, Group III presented with reversibility in the FEV1, FEV6, and FVC in 15(22.4%), 30(44.8%) and 32(47.8%) respectively. Conclusions: The FEV6 might be used as a complementary parameter in bronchodilator reversibility in elderly patients. However, more study will be needed to determine the usefulness of FEV6 in bronchodilator reversibility test. (Tuberc Respir Dis 2006; 61: 227-232)

구조물 건전성 감시를 위한 시간반전 능동감지기법

박현우(Park Hyun-Woo),김승범(Kim Seung-Bum),손훈(Sohn Hoon) 한국구조물진단유지관리학회 2005 한국구조물진단학회 학술발표회논문집 Vol.9 No.2

판에서의 구조물 건전성 감시를 위한 시간반전 능동센싱을 소개한다. 이 시간반전 능동센싱은 현대음향학의 시간반전기법을 근간으로 하고 있다. 시간반전 음향학에 따르면 가진점에서 입사된 입력신호에 대응되는 다른지점의 응답신호를 시간영역에서 반전시킨 후 재입사시키면 가진점에서 원래 입사시킨 입력파를 복원할 수 있다. 이 연구에서는 수치모사 및 실험을 통해 판구조물에서 발생하는 램파의 시간반전성을 이해하고, 시간반전성을 판구조물의 손상진단에 적용할 수 있는지 고찰하였다. Time reversal active sensing is introduced for structural health monitoring (SHM) of a plate. The key idea of this time reversal active sensing is originated from time reversal method of time reversal acoustics. According to the time reversal acoustics, an input signal can be reconstructed at an excitation point if an response signal recorded at another point is reversed in a time domain and emitted back to the original source point. In this study, numerical simulations and experimental studies are conducted to understand the time reversibility of Lamb waves and investigate the applicability of this time reversibility to detecting damage of a plate.