The Application of REDOR NMR to Understand the Conformation of Epothilone B

Lee, Jae-Ho,Kim, Moon-Su,Lee, Hyo Won,Lee, Ihl-Young C.,Kim, Hyun Kyoung,Kim, Nam Doo,Lee, SangGap,Seo, Hwajeong,Paik, Younkee MDPI 2017 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.18 No.7

<P>The structural information of small therapeutic compounds complexed in biological matrices is important for drug developments. However, structural studies on ligands bound to such a large and dynamic system as microtubules are still challenging. This article reports an application of the solid-state NMR technique to investigating the bioactive conformation of epothilone B, a microtubule stabilizing agent, whose analog ixabepilone was approved by the U.S. Food and Drug Administration (FDA) as an anticancer drug. First, an analog of epothilone B was designed and successfully synthesized with deuterium and fluorine labels while keeping the high potency of the drug; Second, a lyophilization protocol was developed to enhance the low sensitivity of solid-state NMR; Third, molecular dynamics information of microtubule-bound epothilone B was revealed by high-resolution NMR spectra in comparison to the non-bound epothilone B; Last, information for the macrolide conformation of microtubule-bound epothilone B was obtained from rotational-echo double-resonance (REDOR) NMR data, suggesting the X-ray crystal structure of the ligand in the P450epoK complex as a possible candidate for the conformation. Our results are important as the first demonstration of using REDOR for studying epothilones. </P>

A Brief Investigation on the Performance Variation and Shelf Lifetime in Polymer:Nonfullerene Solar Cells

Lee, Sooyong,Kim, Hwajeong,Lee, Chulyeon,Kim, Youngkyoo Korea Photovoltaic Society 2019 Current Photovoltaic Research Vol.7 No.3

Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.

Effect of Short-Time Annealing on the Performance of Polymer:Fullerene Solar Cells

Lee, Woongki,Song, Myeonghun,Han, Hyemi,Seo, Jooyeok,Lee, Chulyeon,Kim, Youngkyoo,Kim, Hwajeong American Scientific Publishers 2017 Journal of nanoelectronics and optoelectronics Vol.12 No.6

Effect of Thermal Treatment on the Performance and Nanostructures in Polymer Solar Cells with PTB7-Th:PC₇₁BM Bulk Heterojunction Layers

Lee, Sooyong,Seo, Jooyeok,Jeong, Jaehoon,Lee, Chulyeon,Song, Myeonghun,Kim, Hwajeong,Kim, Youngkyoo Korea Photovoltaic Society 2017 Current Photovoltaic Research Vol.5 No.3

Here we report the influence of thermal treatment on the performance of high efficiency polymer solar cells with the bulk heterojunction films of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b'] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and [6,6]-phenyl $C_{71}$ butyric acid methyl ester ($PC_{71}BM$). The crystalline nanostructure of PTB7-Th:$PC_{71}BM$ layers, which were annealed at three different temperatures, was investigated by employing synchrotron radiation grazing incidence X-ray diffraction (GIXD) technique. Results showed that the device performance was slightly reduced by thermal annealing at $50^{\circ}C$ but became significantly poor by thermal annealing at $100^{\circ}C$. The poor device performance by thermal annealing was attributed to the collapse in the crystalline nanostructure of PTB7-Th in the PTB7-Th:$PC_{71}BM$ layers as evidenced by the GIXD measurements that exhibited huge reduction in the intensity of PTB7-Th (100) peak even at $50^{\circ}C$.

Efficacy of luteal estrogen administration and an early follicular Gonadotropin-releasing hormone antagonist priming protocol in poor responders undergoing in vitro fertilization

( Hwajeong Lee ),( Hyun Joung Choi ),( Kwang Moon Yang ),( Min Jung Kim ),( Sun Hwa Cha ),( Hyun Jeong Yi ) 대한산부인과학회 2018 Obstetrics & Gynecology Science Vol.61 No.1

Objective We investigated whether luteal estrogen administration and an early follicular Gonadotropin-releasing hormone antagonist (E/G-ant) priming protocol improves clinical outcomes in poor responders to controlled ovarian stimulation for in vitro fertilization (IVF)-embryo transfer, and identified underlying mechanisms. Methods This restrospective study consisted of 65 poor responders who underwent the E/G-ant priming protocol. Sixty-four other poor responders undergoing conventional protocols without pretreatment were included as the control group. Clinical outcomes were compared between 2 groups. Results The E/G-ant priming protocol group exhibited improvements over the control group in terms of the number of retrieved oocytes (3.58±2.24 vs. 1.70±1.45; P=0.000), mature oocytes (2.68±2.11 vs. 1.65±1.23; P=0.000), fertilized oocytes (2.25± 1.74 vs. 1.32±1.26; P=0.001), good embryos (1.62±0.91 vs. 1.14±0.90, P=0.021). Day 3 follicle-stimulating hormone (FSH; 8.40±4.84 vs. 16.39±13.56; P=0.000) and pre-ovulation progesterone levels (0.67 vs. 1.28 ng/mL; P=0.016) were significantly higher in the control group than in the E/G-ant priming group. The overall rate of positive human chorionic gonadotropin tests was higher in the E/G-ant priming group than in the control group (32.3% vs.16.1%; P=0.039). Also, clinical pregnancy rate (26.2% vs. 12.5%; P=0.048) and the rate of live births (23.1% vs. 7.1%; P=0.023) were significantly higher in the E/G-ant priming group than in the control group. Conclusion The E/G-ant priming protocol would lead to promising results in poor responders to IVF by suppressing endogenous FSH and by preventing premature luteinization.

Characteristics of Organic Field-Effect Transistors with Quick-Annealed Polymer Channel Layers at High Temperature

Lee, Chulyeon,Seo, Jooyeok,Han, Hyemi,Lee, Woongki,Kim, Hwajeong,Kim, Youngkyoo AMERICAN SCIENTIFIC PUBLISHERS 2017 Journal of nanoelectronics and optoelectronics Vol.12 No.6

리더-구성원 교환관계가 직무만족에 미치는 영향과 성과지향 문화, 관계지향 문화의 조절효과

이화정(Hwajeong Lee),함상우(SangWoo Hahm),이상호(Sanghoo Lee) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.7

Leader-member exchange (LMX) is closely related to the motivation of the members. This study explains the effect of the LMX on the job satisfaction, which is connected to motivation. Moreover, we demonstrate the moderating effect of performance-oriented culture and relation-oriented culture in the relationship between LMX and job satisfaction. If the quality of the LMX is high, the members become more satisfied with the job. However, depending on the specific organizational culture, there will be differences in the influence or role of the LMX. Through the effect of organizational culture we explain the situations in which the LMX is more important, its influence is not important, or the LMX is unnecessary. The purpose of this study is to explain whether the organization should focus more on efforts to improve the quality of LMXs, or on factors other than LMX, depending on the culture characteristics of the organization. 리더-구성원 교환관계는 구성원의 동기부여와 밀접한 관련성이 있다. 동기부여는 자신의 욕구를 만족시키고자 조직의 목표를 위해 자발적으로 임하는 심리상태로 설명된다. 이 연구는 리더-구성원 교환관계가 동기부여와 관련하여 구성원의 직무만족에 미치는 영향을 설명한다. 그리고 리더-구성원 교환관계와 직무만족의 관계에 있어서 성과지향 문화와 관계지향 문화의 조절효과를 입증한다. 리더-구성원 교환관계의 질이 높으면 구성원은 보다 직무에 만족하게 된다. 하지만 특정 조직문화에 따라 리더-구성원 교환관계가 지니는 영향력이나 역할에는 차이가 있을 것이다. 이 연구는 리더-구성원 관계가 보다 중요하거나 그 영향력이 크게 중요하지 않은, 혹은 리더-구성원 교환관계가 불필요한 상황을 조직문화를 통해 설명한다. 그래서 조직이 지니고 있는 문화의 특성에 따라서 리더-구성원 교환관계의 질일 향상시키기 위해 보다 노력을 해야 하는지, 혹은 리더-구성원 교환관계가 아닌 다른 요소들에 초점을 두어야 하는지를 설명하는데 이 연구의 목적과 의의를 둔다.

프랑스 미디어의 인종차별 사건 보도 프레임 분석 : 내집단과 외집단 사이의 차이를 중심으로

이화정(LEE Hwajeong),최윤선(CHOI Yun Son) 프랑스학회 2021 프랑스학연구 Vol.- No.96

본 연구는 인종차별과 관련된 프랑스 미디어 보도를 비판적 담론 분석의 시각으로 분석하였다. 분석 대상으로 2020년 미국에서 발생한 George Floyd 사망 사건과 2016년 프랑스에서 발생한 Adama Traoré 사망 사건을 상호 비교함으로써 동일한 유형의 사건이 내집단(국내)과 외집단(국외) 어느 곳에서 발생했는지에 따라 프랑스 언론 보도 프레임이 어떤 차이를 보이는지를 질적 분석과 양적 분석을 병행하여 분석하였다. 분석 결과 프랑스 언론은 외집단에서 발생한 사망 사건 보도에서는 직접적이고 명확한 어휘를 통해 가해자와 피해자를 명시함으로써 사건의 인과관계를 분명히 하였으며, 사망 사건으로 야기된 시위 보도에서도 시위대에 정당성을 부여하는 방식으로 반인종차별적 보도 프레임을 뚜렷이 견지하였다. 반면 내집단인 프랑스에서 발생한 사건 보도에서는 가해 주체를 의도적으로 생략하고 가해자와 피해자의 인종에 대한 언급을 생략하는 익명화 전략을 취함으로써 인종차별적 프레임을 최대한 희석시키고, 그 대신 시위의 폭력성을 부각시키는 반시위 보도 프레임을 취하였다. 본 연구는 인종차별과 관련된 언론 보도에 있어서 내용이 유사한 사건이라 할지라도 내집단/외집단 소속 여부에 따라 각자의 이해관계를 반영하여 서로 상반된 현실 재구성 보도 프레임을 보인다는 사실을 확인하였다는 점에서 그 의의를 찾을 수 있다. Dans ce travail, on a analysé, dans le cadre de l’analyse critique du discours, le traitement médiatique français des affaires liées au racisme. Pour ce faire, on a procédé à une analyse quantitative et qualitative afin de comparer les événements portant sur la mort de George Floyd, qui a eu lieu aux États-Unis en 2020, et la mort d’Adama Traoré en France en 2017. On a ainsi analysé la différence qu’il y a dans le cadrage médiatique de ces événements de la même nature, en fonction de s’ils ont eu lieu au sein du groupe externe (à l’étranger) ou interne (en France). Suite à l’analyse, on a pu observer que pour relater la mort de Floyd, qui concerne un groupe extérieur, les médias français mettent au clair la causalité de cet événement en précisant l’auteur de violence et la victime par le recours au lexique explicite et clair. Pour parler des manifestations, ils proposent également un point de vue anti-raciste, en accordant la légitimité aux manifestants. En revanche, concernant l’événement Traoré qui a eu lieu au sein de l’endogroupe, donc en France, l’auteur de violence n’est pas mentionné et ce, de manière intentionnelle. L’origine de la victime n’est pas évoquée non plus. Le cadrage raciste ainsi atténuée, l’accent est plutôt mis sur la violence des manifestants. Ainsi, on a pu révéler à travers cette étude que dans le traitement médiatique des faits relatifs au racisme, les médias proposent des cadrages opposés dans la représentation de la réalité, qui reflètent les intérêts de chacun, en fonction de s’ils appartiennent ou non au groupe au sein duquel l’événement a lieu.

Effect of Thermal Treatment on the Performance and Nanostructures in Polymer Solar Cells with PTB7-Th:PC<SUB>71</SUB>BM Bulk Heterojunction Layers

Sooyong Lee,Jooyeok Seo,Jaehoon Jeong,Chulyeon Lee,Myeonghun Song,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2017 Current Photovoltaic Research Vol.5 No.3

Here we report the influence of thermal treatment on the performance of high efficiency polymer solar cells with the bulk heterojunction films of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b"] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). The crystalline nanostructure of PTB7-Th:PC71BM layers, which were annealed at three different temperatures, was investigated by employing synchrotron radiation grazing incidence X-ray diffraction (GIXD) technique. Results showed that the device performance was slightly reduced by thermal annealing at 50°C but became significantly poor by thermal annealing at 100°C. The poor device performance by thermal annealing was attributed to the collapse in the crystalline nanostructure of PTB7-Th in the PTB7-Th:PC71BM layers as evidenced by the GIXD measurements that exhibited huge reduction in the intensity of PTB7-Th (100) peak even at 50°C.

픽셀간의 칼라공간에서의 거리와 이웃관계를 고려하는 클러스터링을 통한 칼라영상 분할 (pp.1038-1045)

이화정(Hwajeong Lee),김황수(Hwangsoo Kim) 한국정보과학회 2000 정보과학회논문지 : 소프트웨어 및 응용 Vol.27 No.10

In this paper, we propose a color image segmentation method based on gravitational clustering using neighborhood relation in spatial domain and distance information in RGB space among pixels. A pixel has color value(R,G,B) in color space and location information(x,y) in spatial domain. Most segmentation algorithms based on clustering have performed their procedure using color space distance after pixels are mapped from spatial domain to color space, ignoring their neighborhood relation; but we use both distance in color space and neighborhood relation in spatial domain. We use gravitational clustering imitating the Law of Gravity as clustering algorithm. Gravitational algorithm automatically determines the number and center values of clusters. We compare the result with other clustering algorithm (K-means). It is shown that the proposed method is efficient in finding exact boundary. 본 논문에서는 칼라공간상의 거리와 이웃정보를 이용한 클러스터링을 통한 칼라영상 분할 방법을 제안한다. 칼라영상의 한 픽셀은 칼라정보(R,G,B)와 위치정보(x,y)를 가진다. 대개의 칼라공간에서의 클러스터링방법은 픽셀을 (R,G,B)공간으로 변환후 (R,G,B)공간상의 분포만을 이용하지만 여기서는 (R,G,B)와 (x,y)모두를 사용하여 클러스터링함으로 영상의 세그먼트들을 찾는다. 클러스터링 방법으로서 인력을 모방하는 중력 클러스터링(gravitational clustering)을 사용하였다. 이 방법은 클러스터의 중심값과 클러스터 수를 미리 정해주지 않아도 자동적으로 결정할 수 있는 장점이 있다. 중력 클러스터링에서 찾은 클러스터 수를 가지고 다른 클러스터링 방법(K-means)에 입력으로 주어 결과를 비교해 본다. 본 논문에서는 이웃관계를 따라 클러스터링하는 것이 정확한 경계선을 찾는데 효과적임을 보여준다.