Observation of Perpendicular Magnetization Using CoFe/Pd Multilayers

Jin Seock Ma,Hyun Cheol Koo,Jongwha Eom,Joonyeon Chang,Suk-Hee Han,Chulwoo Kim 대한금속재료학회(구 대한금속학회) 2007 ELECTRONIC MATERIALS LETTERS Vol.3 No.2

Perpendicular magnetization using CoFe/Pd multilayers is presented. The magnetic behaviors of perpendicular and horizontal direction do not follow the conventional demagnetizing factor theory. The interfacial anisotropy is attributed to the perpendicular magnetization. A ferromagnetic layer is coupled with other ferromagnetic layers, so a thicker Pd layer weakens the perpendicular magnetization. The small thickness changes of both the CoFe and Pd generate tremendous variation of perpendicular anisotropy. In addition, sputtering power also affects the magnetic property of multilayers.

The association of physicians' caring attitude with patient satisfaction: an analysis of the national e-survey data

Park, Chanhyun,Kim, Namhyo,Shin, Dong Yeong,Feldman, Steven R.,Balkrishnan, Rajesh,Chang, Jongwha Korean Society of Hospital Management 2015 병원경영학회지 Vol.20 No.2

환자의 만족도는 더 나은 의료서비스 결과물을 위한 중요 요소이기에, 환자만족도와 관련 요인에 대한 연구는 그 필요성이 대두하고 있다. 따라서, 본 연구는 의사의 환자를 향한 공감적(empathetic) 태도와 같은 잠재적 요인이 환자만족도와 어떤 연관성을 가졌는지를 분석했다. 이를 위해, 편의표본추출법을 통한 환자설문조사 자료 중 총 273,994 개의 사례들을 분석한 단면연구가 수행되었다. 연구의 독립변수 및 종속변수들은 각각 의사의 태도 및 의사와 진료소(office setting or clinic) 관련 환자만족도로 정의되었다. 연구결과에 의하면, 의사와 진료소 관련 환자만족도는 각각 100점 만점에 평균 78.08과 78.62로 나타났고 상응하는 표준편차는 각각 0.14와 0.12였다. 또한, 의사의 태도가 의사와 진료소 관련 환자만족도와 유의한 관계에 있음을 확인하였다(p < 0.001). 의료에 대한 환자만족도를 높이기 위해서는, 의사의 공감적 의사소통 능력개발을 위한 지속적인 노력이 기울여져서 환자에 의한 의사의 공감적 태도가 인지되어 질 수 있기를 본 연구는 제언한다. As patient satisfaction is a crucial component of improved health care outcomes, there is a need to evaluate the relationship between physicians' attitude and patients' satisfaction. The objective of this study is to examine the relationship between patients' satisfaction and physicians' friendly and caring attitudes by using recent physician ratings by patients. Data from a cross-sectional survey using a convenience sampling was utilized to examine the relationship between physicians' attitudes and patients' satisfaction. The independent variable was the physician's attitude, and the dependent variables were patients' satisfaction with the physician and the office setting. A total of 273,994 patients it the US were included. The patients' average (standard deviation, SD) satisfaction with the physician was 78.08 (0.14), and the average (SD) satisfaction with the office setting was 78.62 (0.12) out of 100. Physicians' attitude was a significant predicting factor impacting the patients' satisfaction with the physician and the office setting (p < 0.001). To facilitate patients' satisfaction with healthcare, a continuous effort to develop physicians' ability to communicate in an empathetic manner should be undertaken so that patients perceive their physicians as empathetic.

Urinary bisphenol A versus serum bisphenol A concentration and ovarian reproductive outcomes among IVF patients: Which is a better biomarker of BPA exposure?

Seung Hee Cho,Yohan Choi,Sean Hyungwoo Kim,김상진,Jongwha Chang 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.4

Bisphenol A (BPA) is an endocrine-disrupting compound (EDC) that is used widely in commercial products in the production of polycarbonate plastics for baby and water bottles, epoxy resins for lacquer lining of food and beverage cans and water pipes, dental sealants, dental composites and thermal receipts paper. There is inhibitory effect of BPA on nuclear estrogen (E2) production in granulosa cells of developing follicles that disrupt normal development to the antral follicles via suppression of E2 in granulosa cells of developing follicles during the menstrual cycle followed by reduction in the number of oocytes retrieved in in-vitro fertilization (IVF) patients. Several studies corroborate an inverse association between serum and/or urinary BPA concentration and the IVF outcome: Peak E2 levels and the number of oocytes retrieved. Upon oral ingestion, 99.5% of unconjugated parent BPA (free BPA) is metabolized to either BPA glucuronide (BPA-G) or BPA sulfate (BPA-S). The unconjugated BPA can bind to the estrogen receptors(ER) while conjugated BPA (biologically inactive BPA) do not bind the estrogen receptor(ER). The challenge is to assess the relationship between BPA exposure among infertile patients with respect to follicular response and health during IVF. The establishment of temporal sequence between BPA exposure and infertility would be the research question to answer: Which route is a better biomarker? The advantages of urine BPA collection would provide pragmatic advantages for clinicians in order to practice cost-effective medicine. However, unconjugated BPA measurement (compared to total BPA) introduces challenges in measurement accuracy since unconjugated BPA requires higher magnitude of limit of detection (LOD) with higher risk of contamination from the medical equipment. The difference in route of BPA assessment could introduce bias in the interpretation of results in terms of the association between BPA levels and the number of oocytes. Fujimoto et al. and Bloom et al. analyzed the relationship between serum BPA and IVF outcome in infertile women. It may sound hypothetically justified due to utilizing serum unconjugated BPA, this strategy is not successful in choosing a practical biomarker of BPA exposure due to toxicokinetic properties of BPA metabolism and excretion in humans.

The association of physicians` caring attitude with patient satisfaction: an analysis of the national e-survey data

( Chanhyun Park ),( Namhyo Kim ),( Dong Yeong Shin ),( Steven R. Feldman ),( Rajesh Balkrishnan ),( Jongwha Chang ) 한국병원경영학회 2015 병원경영학회지 Vol.20 No.2

환자의 만족도는 더 나은 의료서비스 결과물을 위한 중요 요소이기에, 환자만족도와 관련 요인에 대한 연구는 그 필요성이 대두하고 있다. 따라서, 본 연구는 의사의 환자를 향한 공감적(empathetic) 태도와 같은 잠재적 요인이 환자만족도와 어떤 연관성을 가졌는지를 분석했다. 이를 위해, 편의표본추출법을 통한 환자설문조사 자료 중 총 273,994 개의 사례들을 분석한 단면연구가 수행되었다. 연구의 독립변수 및 종속변수들은 각각 의사의 태도 및 의사와 진료소(office setting or clinic)관련 환자만족도로 정의되었다. 연구결과에 의하면, 의사와 진료소 관련 환자만족도는 각각 100점 만점에 평균 78.08과 78.62로 나타났고 상응하는 표준편차는 각각 0.14와 0.12였다. 또한, 의사의 태도가 의사와 진료소 관련 환자만족도와 유의한 관계에 있음을 확인하였다(p < 0.001). 의료에 대한 환자만족도를 높이기 위해서는, 의사의 공감적 의사소통 능력개발을 위한 지속적인 노력이 기울여져서 환자에 의한 의사의 공감적 태도가 인지되어 질 수 있기를 본 연구는 제언한다. As patient satisfaction is a crucial component of improved health care outcomes, there is a need to evaluate the relationship between physicians` attitude and patients` satisfaction. The objective of this study is to examine the relationship between patients` satisfaction and physicians` friendly and caring attitudes by using recent physician ratings by patients. Data from a cross-sectional survey using a convenience sampling was utilized to examine the relationship between physicians` attitudes and patients` satisfaction. The independent variable was the physician`s attitude, and the dependent variables were patients` satisfaction with the physician and the office setting. A total of 273,994 patients it the US were included. The patients` average (standard deviation, SD) satisfaction with the physician was 78.08 (0.14), and the average (SD) satisfaction with the office setting was 78.62 (0.12) out of 100. Physicians` attitude was a significant predicting factor impacting the patients` satisfaction with the physician and the office setting (p < 0.001). To facilitate patients` satisfaction with healthcare, a continuous effort to develop physicians` ability to communicate in an empathetic manner should be undertaken so that patients perceive their physicians as empathetic.

황-요오드 공정용 직접접촉 삼산화황 분해반응기내 열전달 특성에 관한 수치적 연구

최재혁(Jae-Hyuk Choi),신영준(Young-Joon Shin),탁남일(Nam-Il Tak),이기영(Ki-Young Lee),장종화(Jongwha Chang),정석호(Suk-Ho Chung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

A directly heated SO₃ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed by using a computational fluid dynamics code(CFD) with the CFX 5.7.1. The use of a directly heated decomposition reactor in conjunction with a VHTR allows higher decomposition reactor operating temperature. However, the thermochemical and hybrid hydrogen production processes accompanied with the high temperature and strongly corrosive operating conditions basically have material problems. In order to resolve these problems, we carried out the development of a structural material and equipment design technologies. The results show that the maximum temperature of the structural material (RA330) could be maintained at 800℃ or less. Also, it can be seen that the mean temperature of the reaction region packed with catalysts in the SO₃ decomposition reactor could satisfy the temperature condition of around 850 ℃ which is the target temperature in this study.

External Gelation 방법을 이용한 구형 UO₃ Gel 입자 제조

정경채,김연구,오승철,조문성,이영우,장종화,Jeong, KyungChai,Kim, YeonKu,Oh, SeungChul,Cho, Moon-Sung,Lee, YoungWoo,Chang, JongWha 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.11

HTGR (High Temperature Gas-cooled Reactor) is spotlighted to next generation nuclear power plant for producing the clean hydrogen gas and the electricity. In this study, the spherical $UO_3$ gel particles were prepared by the external gelation process, and the characteristics of these particles were analyzed the particle shape, composition of precipitate, and thermal decomposition characteristics with the Streoscope, FT-IR, and X-ray diffractometer. Raw material of the ADUN (Acid Deficient Uranyl Nitrate) solution, which has [$NO_3$]/[U] mole ratio = 1.75, was obtained from dissolution of the $U_{3}O_{8}$ powder with concentrated $HNO_3$, and its concentration is 3.5 M-U/l. The broth solution is prepared with the ADUN, urea, PVA, and THFA solution. The droplets of the broth solution was made through a nozzle system. From this study, we obtained the following results; 1) an externel chemical gelation process is a suitable method in the spherical $UO_3$ particle production, 2) the particle shape are changed by an urea mixing time, THFA volume, and the viscosity of the broth solution, 3) the amorphous $UO_3$ particles obtained from these experiments was converted to $U_{3}O_{8}$ and then $UO_2$ by heat treatment in hydrogen atmosphere at $600^{\circ}C$.

Single-Chain Atomic Crystals as Extracellular Matrix-Mimicking Material with Exceptional Biocompatibility and Bioactivity

Lee, Jin Woong,Chae, Sudong,Oh, Seoungbae,Kim, Si Hyun,Choi, Kyung Hwan,Meeseepong, Montri,Chang, Jongwha,Kim, Namsoo,Yong Ho Kim,,Lee, Nae-Eung,Lee, Jung Heon,Choi, Jae-Young American Chemical Society 2018 NANO LETTERS Vol.18 No.12

<P>In this study, Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> single-chain atomic crystals (SCACs) with atomically small chain diameters of ∼0.6 nm, large surface areas, and mechanical flexibility were synthesized and investigated as an extracellular matrix (ECM)-mimicking scaffold material for tissue engineering applications. The proliferation of L-929 and MC3T3-E1 cell lines increased up to 268.4 ± 24.4% and 396.2 ± 8.1%, respectively, after 48 h of culturing with Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCACs. More importantly, this extremely high proliferation was observed when the cells were treated with 200 μg mL<SUP>-1</SUP> of Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCACs, which is above the cytotoxic concentration of most nanomaterials reported earlier. An ECM-mimicking scaffold film prepared by coating Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCACs on a glass substrate enabled the cells to adhere to the surface in a highly stretched manner at the initial stage of cell adhesion. Most cells cultured on the ECM-mimicking scaffold film remained alive; in contrast, a substantial number of cells cultured on glass substrates without the Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCAC coating did not survive. This work not only proves the exceptional biocompatible and bioactive characteristics of the Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCACs but also suggests that, as an ECM-mimicking scaffold material, Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> SCACs can overcome several critical limitations of most other nanomaterials.</P> [FIG OMISSION]</BR>

Exceptional Mechanical Properties of Phase-Separation-Free Mo₃Se₃^--Chain-Reinforced Hydrogel Prepared by Polymer Wrapping Process

Kim, Si Hyun,Oh, Seungbae,Chae, Sudong,Lee, Jin Woong,Choi, Kyung Hwan,Lee, Kyung Eun,Chang, Jongwha,Shi, Liyi,Choi, Jae-Young,Lee, Jung Heon American Chemical Society 2019 Nano letters Vol.19 No.8

<P>As Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> chain nanowires have dimensions comparable to those of natural hydrogel chains (molecular-level diameters of ∼0.6 nm and lengths of several micrometers) and excellent mechanical strength and flexibility, they have large potential to reinforce hydrogels and improve their mechanical properties. When a Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP>-chain-nanowire-gelatin composite hydrogel is prepared simply by mixing Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> nanowires with gelatin, phase separation of the Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> nanowires from the gelatin matrix occurs in the micronetwork, providing only small improvements in their mechanical properties. In contrast, when the surface of the Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> nanowire is wrapped with the gelatin polymer, the chemical compatibility of the Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> nanowire with the gelatin matrix is significantly improved, which enables the fabrication of a phase-separation-free Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP>-reinforced gelatin hydrogel. The composite gelatin hydrogel exhibits significantly improved mechanical properties, including a tensile strength of 27.6 kPa, fracture toughness of 26.9 kJ/m<SUP>3</SUP>, and elastic modulus of 54.8 kPa, which are 367%, 868%, and 378% higher than those of the pure gelatin hydrogel, respectively. Furthermore, the amount of Mo<SUB>3</SUB>Se<SUB>3</SUB><SUP>-</SUP> nanowires added in the composite hydrogel is as low as 0.01 wt %. The improvements in the mechanical properties are significantly larger than those for other reported composite hydrogels reinforced with one-dimensional materials.</P> [FIG OMISSION]</BR>

고온수증기전기분해장치 (HTSE)의 수소 생산 특성에 관한 수치적 연구

최재혁(Jae-Hyuk Choi),김준섭(Jun Sub Kim),신영준(Youngjoon Shin),이기영(Ki-Young Lee),장종화(Jongwha Chang),함영민(Yeong Min Hahm) 한국마린엔지니어링학회 2008 한국마린엔지니어링학회 학술대회 논문집 Vol.2008 No.-

The characteristics of hydrogen production in high temperature steam electrolysis (HTSE) have been numerically analyzed in a two-dimension with the Comsol multiphysics. The main parameters for the calculation are appllied voltage and ASR (Area Specific Resistance). The results showed that thermal neutral voltage was 1.2454 V and a mean temperature in cell was decreased by less than 1.2454 V and it was increased by more than 1.2454 V. This means that the mean temperature in cell is not increase monotonously with increasing the applied voltage. The mean temperature and the rate of hydrogen production in cell were decreased with increase in ASR.

고온수증기전기분해장치(HTSE)의 수소 생산 특성에 관한 수치적 연구

최재혁(Jae-Hyuk Choi),김준섭(Jun Sub Kim),신영준(Youngjoon Shin),이기영(Ki-Young Lee),장종화(Jongwha Chang),함영민(Yeong Min Hahm) 한국항해항만학회 2008 한국항해항만학회 학술대회논문집 Vol.2008 No.공동학술

The characteristics of hydrogen production in high temperature steam electrolysis (HTSE) have been numerically analyzed in a two-dimension with the Comsol multiphysics. The main parameters for the calculation are appllied voltage and ASR (Area Specific Resistance). The results showed that thermal neutral voltage was 1.2454 V and a mean temperature in cell was decreased by less than 1.2454 V and it was increased by more than 1.2454 V. This means that the mean temperature in cell is not increase monotonously with increasing the applied voltage. The mean temperature and the rate of hydrogen production in cell were decreased with increase in ASR.