Effect of delta ferrite on hydrogen embrittlement in GTA weld joint of 316L stainless steel

Jimin Nam(남지민),Jaeseok Yoo(유재석),Seung-gun Lee(이승건),Namhyun Kang(강남현) 대한용접·접합학회 2023 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2023 No.5

Alleviation of Hydrogen Embrittlement to Delay Effective Hydrogen Diffusion Against MA Constituent Formation Due to Mo Solutes for 420 MPa Grade Offshore Steels

Jimin Nam,Junghoon Lee,Hanji Park,Cheolho Park,Changhoon Lee,Junho Chung,Seung‑gun Lee,Namhyun Kang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.6

Hydrogen embrittlement (HE) is a significant issue in high-strength offshore steel. Mo is added for high strength, and severalstudies on the HE resistance by Mo solutes and Mo segregation have been reported. However, the effect of Mo addition onHE in bainitic steels has not been studied yet. This study investigated the effect of increasing Mo content (up to 0.2 wt%) onHE resistance in terms of crack initiation and hydrogen diffusion behaviors in bainitic steels. With the addition of Mo, thestrength of 0.2 Mo steel increased, but it’s HE resistance was nearly identical to that of 0.02 Mo steel. As the Mo contentincreased, the martensite-austenite (MA) constituents sensitive to HE increased; however, the Mo solutes, which serve astrap sites for hydrogen, also increased. The delay in hydrogen diffusion by the Mo solutes played a role in alleviating thedegradation in the HE resistance of the MA constituents of 0.2 Mo steel.

Biological Inspiration toward Artificial Photostystem

Jimin Park,Jung-Ho Lee,Yong-Sun Park,Kyoungsuk Jin,Ki Tae Nam 한국진공학회 2013 한국진공학회 학술발표회초록집 Vol.2013 No.8

Recent Studies of Skin Barrier Research

( Jimin So ),남개원 ( Gaewon Nam ) 한국피부장벽학회 2019 한국피부장벽학회지 Vol.21 No.1

The epidermis, the outermost layer of the skin, functions as skin barrier. The epidermis regulates the outside-in and inside-out penetration of water, nutrients, ions and environmental stimuli. Epidermal cells continuously regenerating, thus to understand dynamically changing characteristics and functions of epidermis, it is important to observe viable epidermal tissues. 3D imaging technique can be used to observe live tissue, however is not suitable for human tissues. Instead, in vitro artificial 3D human epidermis can replace human tissues. 3D skin model is in vitro developed 3-dimensional model mimicking native human skin. It is now broadly used to replacement for animal experiments. 3D skin models have numerous uses. They can be applied to permeability test, toxicity test as well as efficacy test for drugs and cosmetics. In this review, we summarize comprehensive understanding of 3D skin models for skin barrier function study. We report development and application of 3D skin models, current limitations of its use and directions of further investigations.

Association of sleep quality in Behcet disease with disease activity, depression, and quality of life in Korean population

( Jimin Lee ),( Sung-soo Kim ),( Hye-jin Jeong ),( Chang-nam Son ),( Ji-min Kim ),( Yong-won Cho ),( Sang-hyon Kim ) 대한내과학회 2017 The Korean Journal of Internal Medicine Vol.32 No.2

Background/Aims: Sleep disturbance is prime concern in patients with Behcet disease. The purpose of this study was to find out the effects of sleep quality, in Korean patients suffering from Behcet disease. We further investigated the relationship between depression, quality of life and the clinical findings of Behcet disease. Methods: The study was performed by the cross-sectional design. Sleep quality was assessed by the Korean version of Pittsburgh sleep quality index (PSQI). Disease activity of Behcet disease was evaluated by Behcet disease current activity form (BDCAF). Depression was assessed by the Korean version of Beck depression inventory second edition (BDI-2). Quality of life was assessed by the Korean version of the Leeds Behcet disease quality of life measure (BDQoL). Results: Among the 100 patients studied, 42% reported poor sleep quality (PSQI ≥ 9). These patients have a higher BDI-2, total BDCAF and pain visual analogue scale (VAS) score (p < 0.001, p = 0.022, and p = 0.005). Considering BDCAF, the frequency of genital ulcer was significantly higher (p = 0.01). Behcet was higher in females. The BDQoL was lower in poor sleeper group (p = 0.004 and p < 0.001). Among 7 PSQI components, daytime dysfunction was higher in patients with high disease activity (p = 0.03). Total PSQI score were strongly correlated with BDCAF, BDI-2, BDQoL, and pain VAS score (p = 0.02, p < 0.001, p < 0.001, and p < 0.001, respectively). Conclusions: Low sleep quality is directly associated with disease activity, depression, and quality of life in Korean patients with Behcet disease.

Double transduction of a Cre/LoxP lentiviral vector: a simple method to generate kidney cell-specific knockdown mice

Nam, Bo Young,Kim, Dong Ki,Park, Jung Tak,Kang, Hye-Young,Paeng, Jisun,Kim, Seonghun,Park, Jimin,Um, Jae Eun,Oh, Hyung Jung,Han, Seung Hyeok,Yoo, Tae-Hyun,Kang, Shin-Wook American Physiological Society 2015 American Journal of Physiology Vol.309 No.12

<P>In a lentivirus-based gene delivery system, the incorporated gene is continuously expressed for a long time. In this study, we devised a simple way to knock down a specific gene in a kidney cell-specific pattern in adult mice by lentivirus-assisted transfer of short hairpin RNA (shRNA). Kidney collecting duct (CD)-specific aquaporin-3 (AQP3)-knock-down mice were generated by consecutive injection of Hoxb7-Cre-expressing lentivirus (LV-Hoxb7 Cre) and loxP-AQP3 shRNA-expressing lentivirus (LV-loxP shAQP3) in adult C57BL6/J mice. LV-Hoxb7 Cre was designed to express mCherry, while LV-loxP shAQP3 was designed with a floxed enhanced green fluorescent protein (EGFP)-tagged stop sequence, and thus EGFP would be expressed only in the absence of Cre recombination. In mice treated with LV-Hoxb7 Cre alone, mCherry protein expression, which indicates the presence of Cre recombinase, occurred only in CD cells. However, LV-loxP shAQP3 injection alone resulted in an increase in EGFP expression in all kidney cells, indicating the transcription of the floxed region. When LV-Hoxb7 Cre and LV-loxP shAQP3 were sequentially transduced, EGFP expression was attenuated while mCherry expression was sustained in CD cells, demonstrating a CD cell-specific recombination of the floxed region. AQP3 expression in mice injected with LV-Hoxb7 Cre or LV-loxP shAQP3 alone did not differ, but consecutive injection of LV-Hoxb7 Cre and LV-loxP shAQP3 significantly reduced AQP3 expression in CD cells. However, the expression levels of AQP3 were not altered in other cell types. Double transduction of Cre- and loxP-based lentivirus can easily generate kidney cell-specific knockdown mice, and this method might be applicable to other species.</P>

Charge-Transfer-Modulated Transparent Supercapacitor Using Multidentate Molecular Linker and Conductive Transparent Nanoparticle Assembly

Choi, Jimin,Nam, Donghyeon,Shin, Dongyeeb,Song, Youngkwon,Kwon, Cheong Hoon,Cho, Ikjun,Lee, Seung Woo,Cho, Jinhan American Chemical Society 2019 ACS NANO Vol.13 No.11

<P>One of the most critical issues in preparing high-performance transparent supercapacitors (TSCs) is to overcome the trade-off between areal capacitance and optical transmittance as well as that between areal capacitance and rate capability. Herein, we introduce a TSC with high areal capacitance, fast rate capability, and good optical transparency by minimizing the charge transfer resistance between pseudocapacitive nanoparticles (NPs) using molecular linker- and conductive NP-mediated layer-by-layer (LbL) assembly. For this study, bulky ligand-stabilized manganese oxide (MnO) and indium tin oxide (ITO) NP multilayers are LbL-assembled through a ligand exchange reaction between native ligands and small multidentate linkers (tricarballylic acid). The introduced molecular linker substantially decreases the separation distance between neighboring NPs, thereby reducing the contact resistance of electrodes. Moreover, the periodic insertion of ITO NPs into the MnO NP-based electrodes can lower the charge transfer resistance without a meaningful loss of transmittance, which can significantly improve the areal capacitance. The areal capacitances of the ITO NP-free electrode and the ITO NP-incorporated electrode are 24.6 mF cm<SUP>-2</SUP> (at 61.6% transmittance) and 40.5 mF cm<SUP>-2</SUP> (at 60.8%), respectively, which outperforms state of the art TSCs. Furthermore, we demonstrate a flexible symmetric solid-state TSC that exhibits scalable areal capacitance and optical transmittance.</P> [FIG OMISSION]</BR>

A New Water Oxidation Catalyst: Lithium Manganese Pyrophosphate with Tunable Mn Valency

Park, Jimin,Kim, Hyunah,Jin, Kyoungsuk,Lee, Byung Ju,Park, Yong-Sun,Kim, Hyungsub,Park, Inchul,Yang, Ki Dong,Jeong, Hui-Yun,Kim, Jongsoon,Hong, Koo Tak,Jang, Ho Won,Kang, Kisuk,Nam, Ki Tae American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.11

<P>The development of a water oxidation catalyst has been a demanding challenge for the realization of overall water-splitting systems. Although intensive studies have explored the role of Mn element in water oxidation catalysis, it has been difficult to understand whether the catalytic capability originates mainly from either the Mn arrangement or the Mn valency. In this study, to decouple these two factors and to investigate the role of Mn valency on catalysis, we selected a new pyrophosphate-based Mn compound (Li<SUB>2</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB>), which has not been utilized for water oxidation catalysis to date, as a model system. Due to the monophasic behavior of Li<SUB>2</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> with delithiation, the Mn valency of Li<SUB>2-<I>x</I></SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> (<I>x</I> = 0.3, 0.5, 1) can be controlled with negligible change in the crystal framework (e.g., volume change ∼1%). Moreover, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, ex-situ X-ray absorption near-edge structure, galvanostatic charging–discharging, and cyclic voltammetry analysis indicate that Li<SUB>2-<I>x</I></SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> (<I>x</I> = 0.3, 0.5, 1) exhibits high catalytic stability without additional delithiation or phase transformation. Notably, we observed that, as the averaged oxidation state of Mn in Li<SUB>2-<I>x</I></SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> increases from 2 to 3, the catalytic performance is enhanced in the series Li<SUB>2</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> < Li<SUB>1.7</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> < Li<SUB>1.5</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> < LiMnP<SUB>2</SUB>O<SUB>7</SUB>. Moreover, Li<SUB>2</SUB>MnP<SUB>2</SUB>O<SUB>7</SUB> itself exhibits superior catalytic performance compared with MnO or MnO<SUB>2</SUB>. Our study provides valuable guidelines for developing an efficient Mn-based catalyst under neutral conditions with controlled Mn valency and atomic arrangement.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-11/ja410223j/production/images/medium/ja-2013-10223j_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja410223j'>ACS Electronic Supporting Info</A></P>

북한이탈주민 여성의 사회적 배제에 영향을 미치는 요인

남보영 ( Nam Boyoung ),김담이 ( Kim Dam I ),이은형 ( Lee Eunhyung ),김지민 ( Kim Jimin ) 한국사회복지연구회 2021 사회복지연구 Vol.52 No.2

본 연구의 목적은 북한이탈주민 여성들이 경험하는 다양한 차원의 사회적 배제 실태를 탐색하고, 이들의 사회적 배제에 영향을 미치는 요인을 분석하는 것이다. 이를 위해 서울, 인천, 경기 지역에 거주하는 만 19세 이상 북한이탈주민 여성을 대상으로 자기보고식 설문지를 통해 데이터를 수집하였으며, 최종 모형에는 155명의 북한이탈주민 여성이 포함되었다. 본 연구는 남한사회 정착 이전 요인과 남한사회 정착 이후 요인이 사회적 배제에 미치는 영향을 전체 사회적 배제 및 사회적 배제의 4가지 하위차원(사회적교류, 정치적관여, 생산활동, 소비활동)으로 나누어 다중회귀분석을 통해 분석하였다. 주요 연구결과는 다음과 같다. 첫째, 남한사회 정착 이후 요인 중 기초생활수급 및 차상위계층 여부, 자기은폐성이 전체 사회적 배제 수준에 통계적으로 유의미한 영향을 미치는 것으로 확인되었다. 둘째, 북한학력, 남한정규교육 유무, 자기은폐성이 사회적 배제의 하위 차원인 사회적 교류의 배제에 영향을 미치는 것으로 확인되었다. 셋째, 취업 유무, 기초생활수급 및 차상위계층 여부가 생산 활동의 배제에 영향을 미치는 것으로 나타났다. 넷째, 외상 경험이 소비 활동의 배제에 영향을 미치는 것으로 확인되었다. 마지막으로 정치적 관여의 배제에는 통계적으로 유의미한 영향을 미치는 요인이 없는 것으로 나타났다. 이러한 분석결과를 바탕으로 본 연구는 직업훈련 프로그램 활성화 및 고용지원금과 취업장려금 확대를 통한 경제적 자립 지원 등을 사회복지 정책적, 실천적 개입방안으로 제언하였다. The purpose of this study was to explore levels of social exclusion among North Korean refugee women and to analyze risk factors of various types of social exclusion. Data were collected from adult North Korean refugee women (19 or older) residing in Seoul, Incheon, and Gyeonggi areas using a snowball sampling method. The final model included 155 North Korean refugee women. Social exclusion was regressed on pre-resettlement (e.g., duration in the intermediate countries, trauma exposure, educational attainment in North Korea) and post-resettlement risk factors (e.g., employment status, marital status, social stigma, self-concealment, public assistance, duration in South Korea). We first analyzed the overall social exclusion (sum of scores) then separately analyzed each of the four dimensions of social exclusion: exclusion from social exchange (1), production activities (2), consumption activities (3), and political involvement (4). The results showed that self-concealment and public assistance had a statistically significant association with overall social exclusion. When separately analyzed by dimensions, educational attainment, and self-concealment were associated with the exclusion of social exchange. Employment status and public assistance were associated with the exclusion from production activities. In addition, trauma exposure was significantly associated with the exclusion from consumption activities. On the other hand, there were no statistically significant risk factors for the exclusion from political involvement. Findings from this study suggested social welfare policy and practice should focus on enhancing economic self-reliance to prevent social exclusion among North Korean refugee women.

SRAM 기반 PUF 시스템의 Discard-rate 분석

유지민(Jimin Yoo),남재원(Jae-Won Nam),홍종필(Jong-Phil Hong) 대한전자공학회 2022 대한전자공학회 학술대회 Vol.2022 No.6