An inkjet printing method: Drop and Synthesis (DAS). Application to the synthesis of ZnS:Mn nano-phosphor with a pattern

Cha, H.,Ahn, S.I.,Choi, K.C. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.4

An inkjet printing method was introduced to synthesize materials with a pattern, which have been very difficult to print by normal inkjet printers. Based on the proposed method, ZnS:Mn nano-phosphor was synthesized with a pattern by a chemical reaction with two different reactive inks. The nano-phosphor had mostly hexagonal-type structures with an average size of 20 nm. Photoluminescence and cathodoluminescence spectra showed an intensity resonance between peaks at 441 nm and 597 nm depending on a capping agent, which means that the Mn<SUP>2+</SUP> ion was incorporated into the vacancy sites of ZnS lattice after the formation of vacancies in ZnS.

Nitrogen-doped open pore channeled graphene facilitating electrochemical performance of TiO2 nanoparticles as an anode material for sodium ion batteries

Cha, H.,Jeong, H.,Kang, J. Royal Society of Chemistry 2014 Journal of Materials Chemistry A Vol.2 No.15

We report that titanium dioxide nanoparticles anchored on nitrogen-doped open pore channeled graphene exhibit high performance as anode materials for sodium ion batteries with a high reversible capacity of 405 mA h g(-1) at a current density of 50 mA g(-1), excellent cycle stability with a capacity of 250 mA h g(-1) over 100 charge-discharge cycles at a current density of 100 mA g(-1), and superior rate capability. Also, it shows that high electrochemical performance is attributed to the facilitated ion diffusion by their open pore channels, in addition to the promoted electron transfer in electrochemical reactions by nitrogen-doping.

Development of bulk heterojunction morphology by the difference of intermolecular interaction behaviors

Cha, H.,Baek, J.Y.,An, T.K.,Kim, S.O.,Kwon, S.K.,Kim, Y.H.,Park, C.E. Elsevier Science 2014 ORGANIC ELECTRONICS Vol.15 No.12

The morphology of a bulk heterojunction can be controlled by adding a processing additive in order to improve its power conversion efficiency (PCE) in photovoltaic devices. The phase-separated morphologies of blends of PONTBT or P3HT with fullerene derivatives are systematically examined in the presence of processing additives that possess various alkane alkyl chain lengths or end-group electronegativities. We determined the morphologies of the bulk heterojunction layers by using atomic force microscopy (AFM) and grazing incidence wide angle X-ray scattering (GIWAXS). The photocurrent-voltage characteristics of the bulk heterojunction solar cells were found to be strongly dependent on the intermolecular interactions between the conjugated polymers, the fullerene derivatives, and the processing additives in the photoactive layer. The optimal PONTBT:fullerene derivative blend morphology was obtained with a processing additive, 1,3-diiodopropane (1,3-DIP), that possesses a short alkyl chain and an end group with weak electronegativity, and was found to exhibit a high fill factor (FF) and a high current density (J<SUB>SC</SUB>). In contrast, in blends of P3HT with the fullerene derivative, PCEs with higher FF and J<SUB>SC</SUB> values were achieved by incorporating the processing additive, 1,8-dibromooctane (1,8-DBrO), which has a long alkyl chain and a strong electronegative end group. Thus the selection of the processing additive with the aim of enhancing photovoltaic performance needs to take into account the intermolecular interaction of the conjugated polymer.

Life History and Taxonomy of Aglaothamnion oosumiense Itono(Ceramiaceae, Rhodophyta)

Chah,Ok Kyong,Kim, Gwang Hoon 公州大學校 基礎科學硏究所 1998 自然科學硏究 Vol.7 No.-

Life history and post-fertilization process of Aglaothamnion oosumiense from Korea were studied in culture. This species showed a Polysiphonia-type life history with dioecious gametophyte as well as asexual reproduction via parasporangium on male plants. The occurrence of parasporangium plants was not affected by environmental factors nor inherited strictly to the next generation. Most (>95%) of the paraspores developed into male plants, while less than 5% of paraspores became parasporangiate male plants again. Bisexual plants were also observed. Each carpogonial branch had two auxiliary cells, which divided distally to produce the primary gonimoblast initials, respectively, before the foot cells were cut off proximately from it by intercalary divisions. Two carposporophytes resulted from a successful fertilization. Morphologically, Aglaothamnion posumiense resembled Aglaothamnion callophyllidicola(Yamada) Boo, Lee, Rueness et Yoshida, and the taxonomic characters separating them were found to be unstable. The taxonomic relationship between the two species, therefore, should be critically reassessed with a thorough reexamination including their type specimens.

A Study on the Relative Perceived Importance of Leadership Attributes in the U.S. and Korea

Chah,Dong Ok 成均館大學校 韓國産業硏究所 1995 韓國經濟 Vol.21 No.2

최근 사회인지이론이 조직행동론 분야에서 광범위하게 사용되고 또 조직에 대한 국가문화의 영향에 관하여 국제적인 토론이 빈번해지고 있다. 본 논문에서는 이러한 두가지 흐름을 리더쉽 연구에 받아들여 한국과 미국의 중간관리자들은 효과적인 최고경영자가 갖추어야 할 여러 리더쉽 특질들에 대해 어떻게 생각하고 있는가?를 조사하였다. 본 연구의 결과를 종합해 볼 때 리더의 유효성을 설명하는 리더쉽 특질은 두 문화간에 큰 차이가 없었다. 이는 본 연구에서 제시된 '수렴(convergence)' 가정에 근거한「리더쉽 모델」의 일반화를 뒷받침하는 한 증거가 될 수 있다 하겠다.

CONSUMPTION BEHAVIOR AND LIQUIDITY CONSTRAINTS

CHAH, EUN YOUNG 한국경제학회 1995 The Korean Economic Review Vol.11 No.1

ADJUSTMENT COSTS, DURABLES AND INTERTEMPORAL SUBSTITUTION

CHAH, EUN YOUNG 梨花女子大學校 法政大學 1995 社會科學論集 Vol.15 No.-

Efficacy of ketamine in the treatment of migraines and other unspecified primary headache disorders compared to placebo and other interventions: a systematic review

Chah, Neysan,Jones, Mike,Milord, Steve,Al-Eryani, Kamal,Enciso, Reyes The Korean Dental Society of Anesthsiology 2021 Journal of Dental Anesthesia and Pain Medicine Vol.21 No.5

Background: Migraine headaches are the second leading cause of disability worldwide and are responsible for significant morbidity, reduction in the quality of life, and loss of productivity on a global scale. The purpose of this systematic review and meta-analysis was to evaluate the efficacy of ketamine on migraines and other primary headache disorders compared to placebo and other active interventions, such as midazolam, metoclopramide/diphenhydramine, and prochlorperazine/diphenhydramine. Methods: An electronic search of databases published up to February 2021, including Medline via PubMed, EMBASE, Web of Science, and Cochrane Library, a hand search of the bibliographies of the included studies, as well as literature and systematic reviews found through the search was conducted to identify randomized controlled trials (RCTs) investigating ketamine in the treatment of migraine/headache disorders compared to the placebo. The authors assessed the risk of bias according to the Cochrane Handbook guidelines. Results: The initial search strategy yielded 398 unduplicated references, which were independently assessed by three review authors. After evaluation, this number was reduced to five RCTs (two unclear risk of bias and three high risk of bias). The total number of patients in all the studies was 193. Due to the high risk of bias, small sample size, heterogeneity of the outcomes reported, and heterogeneity of the comparison groups, the quality of the evidence was very low. One RCT reported that intranasal ketamine was superior to intranasal midazolam in improving the aura attack severity, but not duration, while another reported that intranasal ketamine was not superior to metoclopramide and diphenhydramine in reducing the headache severity. In one trial, subcutaneous ketamine was superior to saline in migraine severity reduction; however, intravenous (I.V.) ketamine was inferior to I.V. prochlorperazine and diphenhydramine in another study. Conclusion: Further double-blind controlled studies are needed to assess the efficacy of ketamine in treating acute and chronic refractory migraines and other primary headaches using intranasal and subcutaneous routes. These studies should include a long-term follow-up and different ketamine dosages in diagnosed patients following international standards for diagnosing headache/migraine.

中宗初의 政治變化와 士林의 成長

車周泳(Chah, Joo-Young) 백산학회 2004 白山學報 Vol.- No.70

As meritorious retainers who hold power through the dethronement of King Yeonsan by King Jungjong became weak, King Jungjong lost its political foundation. Thus he tried to pick up new figures in order to reinforce his position and found that Sarim people were suitable in morality for his purpose. The Sarim power laid the political base through appealing the restoration of deposed queen Shin in the 10th year of the reign of King Jungjong and carried out political reformation, containing conservative powers based on Sung Confucianism. Through executing Hyangyak they pursued the expansion of Sung Confucianism and the establishment of the autonomous order of local communities, and through executing Hyeonryanggwa and deleting false merits they undermined conservative powers. Reformation by the Sarim power, however, drove King Jungjong and conservative powers to tie with each other out of political crisis and finally ended in Gimyo Sahwa. Sarim people during the period from the early reign of King Jungjong to the early reign of King Seonjo grew politically, materializing the theory of Silsagusi (‘Seek truth from practice’) based on Sung-Confucian political thought. They can be regarded as the Sarim power in the 16th century. They left great influences on later political thoughts and reformations. Thus the Sarim power is extremely important in history.

집권세력의 갈등을 통해 본 중종대의 정치구조

차주영(Chah, Joo-Young) 백산학회 2008 白山學報 Vol.- No.79

이 글은 김안로라는 인물의 권력 강화과정을 중심으로 변화가 심했던 중종대의 정치구조를 살펴본 것이다. 16세기 중종대는 조선 초기 정권을 담당해왔던 훈구세력과 새로이 성장한 사림 세력이 공존하며 정치를 이끌어나간 시기였다. 중종의 왕권강화 노력으로 인해 발탁되어 성장해갔던 사림은 기묘사화로 많은 피해를 입고 세력이 약화되었다. 그러나 훈구세력이 중종초와 같은 권력독점을 다시 이루기는 어려워졌다. 이미 중종은 대응세력 양성을 통한 권력균형을 꾀하고 있었기 때문이다. 이러한 가운데서 정치적으로 부상한 인물이 김안로다. 김안로는 중종과 사돈관계를 맺으면서 권력의 핵심으로 떠올랐고, 어린 세자를 보호한다는 핑계로 권력을 강화하고자 하였다. 김안로는 당시 존재하던 정치세력들과 비슷한 정치행보를 보인것 같지만, 엄밀히 따져보면 그들과 다른 성향의 정치인이었다. 그는 기존의 세력들을 공격하거나 이용하는 방법을 통해 독자적인 권력을 획득해 나갔다. 집권 훈구 세력과 대립하며 성장했고, 청렴한 이미지의 사림을 정치적으로 이용하면서 명분을 쌓았다. 김안로의 정치적 처신에 따라 중종말의 정치형태는 어느 정도 달라질 수 있었을 것이다. 왕의 지지를 배경으로 한 그가 개인적인 욕심을 줄이고 여러 가능성을 염두에 두었다면 명종대ㆍ선조대의 정치도 모습을 달리했을 수 있다. 김안로의 정치적 부침은 훈구세력의 몰락과 척신정치의 고착화라는 결과를 초래하였다. 사상이나 행동을 함께하는 정치세력들이 존재하는 가운데에서 독자적인 정치를 주도해갔던 김안로의 권력 강화 노력과 실패과정을 통해 집권세력의 갈등이 지속되었던 중종대 정치구조를 살펴볼 수 있다. The 16th century was an age when the Hun-gu faction, which had seized power since early Joseon, and the Sarim faction, which emerged as new power, coexisted to lead the politics. In King Jungjong’s days, when the Hun-gu faction regained its power with Sarim’s influence weakened due to Gimyosahwa, Kim An-ro rose to the core of the political power through his family members’ marriages to members of the royal family. Though he had features of the existent Hun-gu faction, Sarim faction, and kingly maternal kin to a certain extent, strictly speaking, he was a different politician from them. Rather than belonging to a single party, he strengthened his power while being opposed to the ruling Hun-gu faction on one hand, and using the Sarim faction with clean images politically. With such a disposition, Kim An-ro can be said to have influence subsequent political changes with his political steps. As he led his own politics in spite of the existence of political colleagues with similar political recognition, Kim An-ro’s efforts to strengthen his power and the process of his failure showed a picture of a politician at that time though his liquidation by Cheoksin (King’s men as kin) resulted in the consolidation of the Cheoksin politics in King Myeongjong’s days.