예비 초등영어 교사의 교수유형의 변화 및 교수유형과 학습유형의 관계 분석

김재혁,Kim Jaehyuk 한국초등영어교육학회 2015 초등영어교육 Vol.21 No.2

The purpose of this study is to suggest ways to diversify the teaching styles of pre-service elementary English teachers by investigating their teaching and learning styles. Specifically, this study intends to examine a) how the teaching styles of pre-service elementary English teachers change during their practicum and, b) how their learning styles are related to their teaching styles. Two teaching styles questionnaires (one before the practicum and another after the practicum) and a learning styles questionnaire were designed and distributed to a sample of 34 pre-service English teachers at a university in Korea who took their teaching practicum in their senior year. The analysis of the data revealed that before the practicum, the facilitator style, a learner-centered approach that views the teacher’s role as a facilitator of student learning, was the dominant, preferred teaching style. However, after the practicum, the subjects developed a more positive attitude toward the personal model style, a teacher-centered approach that views the teacher’s role as more of an authority in presenting information. The data also revealed that some of their learning styles were significantly related to their teaching styles. Those with individual, dependent and collaborative learning styles were found to prefer the facilitator teaching style, but those with group, independent and competitive learning styles tended to use the personal model style. These findings suggest that pre-service teachers try teaching in the styles they are reluctant to use in order to diversify their teaching styles in the classroom. Pedagogical implications for teacher education are also discussed.

Curet과 Ultrasonic Scaler를 이용한 치주치료후 SEM과 EPMA를 이용한 잔존치근면에 대한 연구

김재혁,김종여,임성빈,정진형,Kim, Jae-Hyuk,Kim, Chong-Yeo,Lim, Sung-Bin,Chung, Chin-Hyung 대한치주과학회 1999 Journal of Periodontal & Implant Science Vol.29 No.2

One of the fundamental causes of periodontal disease is accumulation of bacterial plaque and calculus and most effective method of removing these plaque and calculus are scaling and root planning using hand curet and ultrasonic scaler. Many studies concerning residual degenerated mineral content after periodontal therapies have been carried out, but some problems about these studies were also known. This research studies mineral concents and distribution of residual root surfaces after perfoming hand curet and ultrasonic scaler on root surfaces of single rooted teeth which were extracted for periodontal reasons. EPMA were used to avoid errors from chemical quantative analysis and in addition SEM observation was also performed. The results were as follows. 1. No differences were found between curet group andultrasonic scaler group in Ca, P, Mg and Na level. 2. Concentration level was decreased in the sequence of Ca, P, Mg and Na. 3. Ca and P level were decreased as going to apical portion at curet group and ultrasonic scaler group. 4. More cementum was removed at cervical portion compared to other portion at curet group and ultrasonic scaler group. 5. Ca, P, Mg level was higher in dentin compared to cememtum. There was no difference in mineral level for Ca, P, Mg and Na between root surfaces treated with hand curet and ultrasonic scaler.

매식체 표면처리에 따른 생물학적 특성에 대한 연구

김재혁,정진형,임성빈,홍기석,Kim, Jae-Hyuk,Chung, Chin-Hyung,Lim, Sung-Bin,Hong, Ki-Seok 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.3

Purpose: The purpose of this research is to study about initial adhesion, proliferation and activation of osteoblast to titanium surface treated with machined, hydroxyapatite coating, resorbable blast material blasting and anodizing method. Material and Methods: After treating the titanium surface of each block with machined, impurities were removed and sterilized. The number of cells attached from cultured osteoblast of respective experimental groups were measured at 1, 4, 7, and 14day and alkaline phosphatase, calcium, and inorganic phosphate concentration of cultured solution was measured. Result: Anodizing group showed the highest rate of cell attachment and proliferation activity. RBM treated group showed the highest increasing on their alkaline phosphatase activity, on the calcium apposition, on inorganic phosphate apposition of 1 and 4 days in cultured osteoblast to compare with other groups. Conclusion: On the basis of these findings, we conclude that surface modification of titanium was profoundly effected on the attachment, proliferation and activation of osteoblast in initial stage osseointegration.

Li₂O-Bi₂O₃ 첨가가 Pb(Mg_1/3Nb_2/3)_0.65Ti_0.35O₃ 세라믹의 압전 특성에 미치는 영향

김재혁,김시연,최정식,여동훈,신효순,남산,Kim, Jae Hyuk,Kim, Shi Yeon,Choi, Jeoung Sik,Yeo, Dong-Hun,Shin, Hyo-Soon,Nahm, Sahn 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.5

Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

궤도상 위성의 광학관측가능성 해석을 위한 궤도전파 시뮬레이터 개발

김재혁,조중현,박찬덕,박상영,문홍규,임홍서,최영준,최진,박장현,Kim, Jae-Hyeok,Jo, Jung-Hyeon,Park, Chan-Deok,Park, Sang-Yeong,Mun, Hong-Gyu,Im, Hong-Seo,Choe, Yeong-Jun,Choe, Jin,Park, Jang-Hyeon 한국천문학회 2012 天文學會報 Vol.37 No.2

이 연구는 우주물체에 대한 광학감시 및 추적을 수행하기 위한 선행연구로, 궤도전파 시뮬레이터를 개발하여 궤도상 위성의 광학관측가능성을 분석하고 광학관측 여부를 판단하는 것을 목표로 한다. 연구의 주 내용은 주어진 궤도정보를 바탕으로 하는 태양동기궤도(Sun-Synchronous Orbit; SSO) 위성, Dawn-dusk 위성, 저궤도(Low Earth Orbit; LEO) 위성, 정지궤도(Geostationary Orbit; GEO) 위성 등 궤도상 위성의 추정궤도 전파와 자국위성의 광학관측가능성 분석으로 구성된다. 각각의 궤도전파 정밀도 및 광학관측가능성 분석성능을 확인하기 위해 AGI(Analytical Graphics Incorporated)사의 STK(Satellite Tool Kit) 시뮬레이션 프로그램을 사용하여 개발된 궤도전파 시뮬레이터와 비교하였다. 시뮬레이션 과정에서 광학관측의 제한조건을, 지구반영(penumbra)과 태양직사광(direct sun)에서만 관측하며, 고도(elevation angle)의 최소값은 20도, 태양고도(Sun elevation angle)의 최대값은 -10도로 설정하였다. 광학관측이 이루어지는 가상의 관측소는 임의로 선정하였으며, 기본적인 관측시간은 1년으로 잡고, 계절의 변화에 따른 광학관측가능성 궤적의 변화를 보기위해 춘하추동에 대해서 각각 3일이내의 기간 동안 시뮬레이션을 수행하였다. 결과적으로, 우주물체 광학감시 및 추적을 수행하기 위한 광학관측가능성 분석성능은 궤도전파 시뮬레이터 및 초기궤도요소 정밀도, 좌표변환과정 오차 등의 영향을 받으며, 설정된 제한조건에 따라 광학관측 지속시간의 차이가 발생한다. 연구결과를 통해 궤도상 위성의 궤도를 추정하기 위한 위성의 궤도전파 시뮬레이터를 개발하고, 자국위성의 관측가능성 분석을 통해 광학감시 및 추적시스템의 운영이 원활히 이루어질 수 있도록 한다.

저녹스버너 보급사업에 따른 오염물질 저감효과 분석 및 발전방안

김재혁(Jae Hyuck, Kim),김장원(Jang Won, Kim),김형석(Hyung Seok, Kim),이광호(Kwang Ho, Lee),유경선(Kyung Seun, Yoo) 한국환경정책학회 2014 環境政策 Vol.22 No.1

그리드포밍 제어 방식을 적용한 MMC HVDC 시스템의 전력 진동 감쇠 성능 분석

김재혁(Jae-hyuk Kim),김형승(Hyung-seung Kim),김현준(Hyun-jun Kim),이준철(Jun-chol Lee),정홍주(Hong-ju Jung) 전력전자학회 2023 전력전자학술대회 논문집 Vol.2023 No.7

DDS에서 효율적 데이터전송을 위한 네트워크전송기술

김경태(Kyeong Tae Kim),이수형(Soo Hyung Lee),전형국(Hyung-Kook Jeon),김재혁(Jae Hyun Kim),김용연(Yong Yeon Kim),김원태(Won-Tae Kim),박승민(Seung-Min Park) 제어로봇시스템학회 2011 제어로봇시스템학회 합동학술대회 논문집 Vol.1 No.1

최근 네트워크 중심전(NCW)으로 발전하는 국방기술분야에 대규모 실시간 데이터 통신을 위해 미들웨어 표준기술인 DDS(Data Distribution Service)가 적용되고 있다. 하지만 기존 DDS 기술은 국방체계통신객체를 탐색하는 시간이 오래 걸리고, 실시간성을 보장하는 대규모 고신뢰 통신에 한계를 나타내며, 모빌리티가 발생하는 무선통신환경을 고려하지 않고 있다. 따라서 본 논문에서는 DDS에서 보다 효율적인 데이터 전송을 위한 네트워크전송 기술을 제안하였다. 제안된 기술은 DDS 상호운영성을 위반하지 않으면서도 1) 통신객체고속탐색, 2) 실시간 고신뢰성을 위한 하이브리드 멀티캐스팅, 3) 무선통신환경에서 모빌리티 지원을 위한 네트워크통신을 지원한다.

흔적 읽기로서의 번역과정 연구 - 횔덜린의 시 < 반평생 Hälfte des Lebens >을 중심으로

김재혁 ( Kim Jae Hyeok ) 한국헤세학회 2011 헤세연구 Vol.25 No.-

Mit „Übersetzen“ meint man normalerweise eine sinngemäße und möglichst wortgetreue Übertragung eines meist schriftlich fixierten Textes von einer Ausgangssprache in eine Zielsprache. Aber reichen diese Kriterien aus, um von einer erfolgreichen Übersetzung eines literarischen Textes in die eigene Muttersprache zu sprechen? Falls es sich um die Übersetzung eines fremdsprachigen Gedichts handelt, ist es sehr schwer, mit diesem einfachen Verfahren eine dem Ausgangstext würdige Übertragung hervorzubringen. Worin liegt der Grund dafür? Der Grund dafür liegt meistens in der Tatsache, dass der Übersetzer die zugrunde liegende ästhetische Struktur, die sich in dem betreffenden Gedicht nicht immer sofort offenbart, missachtet. Jeder Text enthält verborgene Spuren, die der Dichter beim Schreiben des Textes mehr oder weniger unbewusst hinterlassen hat und die es erst möglich machen, den Text zu verstehen, nachdem wir sie aufgespürt und entziffert haben. Wenn sich eine Übersetzung jedoch nur auf die deutlich sichtbaren Zeichen der Textoberfläche beschränkt - sie sozusagen auf der Ebene der Denotation stehen bleibt -, lässt sich eine vollständige Wiederbelebung des Textes in andere Sprache – etwa im Sinne von Goethes Gedicht Ein Gleichnis - schwerlich erreichen. Der Begriff der „Spurensuche“ soll diesem textexegetischen Sachverhalt Rechnung tragen, da er in adäquater Weise zum Ausdruck bringt, wie man sich im Labyrinth des zu übersetzenden literarischen Textes orientieren sollte. Spurenlesen ist ein Vorgang des Verstehens, weil es in den sichtbaren Zeichen der Textoberfläche viele unsichtbare Spuren gibt, die man finden und entschlüsseln muss. Unsere Arbeit ähnelt der des Archäologen, insofern wir die unterhalb der Textoberfläche versteckten Spuren ans Licht bringen müssen, um erfolgreich in unserem Tun sein zu können. Was ist das für ein Erfolg, den wir daraus ziehen können? Zuerst kann man die Tiefe des betreffenden Textes ausloten, um dadurch einen besseren Einblick in das Funktionieren des Textes zu gewinnen und so in der Übersetzung das nachzuvollziehen, was der Dichter in seinem Schreiben vollzogen hat. Kurz gesagt, man kann die Koordinaten, an denen man sich befindet, richtig lesen und die einzuschlagende Richtungen auerkennen. Am Gedicht Hälfte des Lebens von Friedrich Hölderlin, eines seiner meist Genannten und vielmals Vertonten, soll diese Methode beispielhaft demonstriert werden. Stilistisch gesehen, ist das Gedicht so einfach, dass man glauben könnte, es bereite nicht allzu viele Probleme in der Auslegung. Jedoch stecken in diesem Gedicht viele Spuren, die eine gewöhnliche und an der Oberfläche orientierte Auslegung zwangsläufig übersieht. So wurde es mit Verweis auf den Titel Hälfte des Lebens häufig aus der Perspektive des an einer Midlife-Crisis leidenden Ichs interpretiert. Die 1. Strophe wird als Reflexion der hellen glücklichen Seite der Jugend betrachtet, während die 2. Strophe die dunkle Seite der bevorstehenden ängstlichen Jahre des Alters betrachtet. Diese Interpretation ist möglich, weil das Gedicht aus zwei inhaltlich extrem polaren Strophen besteht, jedoch übersieht sie einiges. Beispiele dafür, welche Art von Spuren Hölderlin in diesem Gedicht hinterlassen hat, sind etwa die sprachlichen und philosophischen Referenzen zur griechischen Sprache und Kultur, zu seinem ästhetischen Ideal(Adonis) sowie Spuren zum Entstehungsprozess dieses Gedichts. Eine Übersetzung darf daher die Lebensspuren des Dichters und dessen ästhetische Vorstellungen nicht unberücksichtigt lassen und sollte sich ganz auf die Wiederbelebung des Textes konzentrieren, ohne die narzisstische Vertikal-Bewegung des lyrischen Ichs in der 1. Strophe und die leere Landschaft der 2. Strophe dabei außer Acht zu lassen. Ein Übersetzer, der solche scheinbar bedeutungslosen, weil scheinbar absichtslosen Text-Spuren aufdeckt und mit neuem Leben füllt, ermöglicht einen größeren übersetzerischen Reichtum und ein tieferes und genaueres Verständnis des zu übersetzendenTextes.

1인당 탄소배출 수렴가설 검정 : 105개국 동태적 패널임계 분석

김재혁 ( Jaehyeok Kim ),조하현 ( Ha-hyun Jo ) 한국국제통상학회 2017 국제통상연구 Vol.22 No.1

본 논문은 105개 국가의 1인당 탄소배출 수렴현상과 소득-탄소배출의 탈동조화 현상을 국면전환모형인 동태적 패널임계모형(dynamic panel threshold model)으로 분석하였다. 탄소배출의 수렴가설과 소득-탄소배출의 탈동조화는 각각 경제성장의 수렴가설과 EKC가설에 의해 뒷받침되고 있다. 105개 국가의 1965∼2009년 대규모 패널자료를 활용하였으며 국가그룹을 지역별, 소득별, 제조업 비중별, 청정에너지 비중별 그룹으로 다양하게 분류하여 세밀한 분석을 수행하였다. 수렴현상은 지역별로는 전체국가, 유럽, 아메리카, MENA에서, 소득별 그룹에서는 고소득과 중소득 그룹에서 조건부 수렴이 성립하였다. 또한, 제조업 상위 그룹, 청정에너지 상위와 하위 그룹에서 수렴이 나타났다. 소득-탄소배출의 탈동조화는 고소득 그룹과 청정에너지 하위 그룹에서 강한 탈동조화를 보인 반면, 전체 국가와 아시아 및 태평양 그룹에서는 약한 탈동조화를 보였다. 아시아 및 태평양의 탈동조화를 야기하는 임계소득은 약 $14,000로 경제적인 의미가 있는 수치였다. 반면, 전체국가와 고소득 그룹의 임계소득은 약 $7,000로 추정되어 다소 낮았다. 청정에너지 하위 그룹의 임계소득은 약 $540, 저소득 그룹의 임계소득은 약 $250로 추정되었다. 논문에서 수렴속도를 비교해 본 결과 전체국가, 아메리카, MENA는 빠른 속도로 수렴하고 있으며 아시아 및 태평양, 사하라 이남, 저소득 국가에서는 아직 수렴이 나타나지 않았다. 이 국가들은 향후 전 세계적인 온실가스배출을 증가시키는데 상당한 역할을 할 가능성이 높은 반면 배출저감 여력도 높다. 따라서 이 국가들을 대상으로 경제발전은 지속하면서 배출저감을 이끌 수 있는 청정개발체제(CDM)와 같은 정책 공조가 더욱 증가하여야 할 것으로 보인다. This study investigates the convergence of per capita carbon emissions and the decoupling of income-emission by estimating the dynamic panel threshold model. The emission convergence and the decoupling of income-emission phenomenon is underpinned by the growth convergence and the EKC hypothesis. Using 105 countries with 1965∼2009 annual large panel data set, we divide the countries into several groups by region, income, industry ratio and clean energy ratio classifications. The convergence holds for total country, Europe, America and MENA in regional group and high-income and middle-income in income group. It also holds for high-industry, high-clean and low-clean group. The income-emission decoupling strongly holds for high-income group and low-clean group and weakly holds for total country and Asia-Pacific group. The threshold income triggering the decoupling is estimated about $14,000 in Asia-Pacific, which is quite economically reasonable level. While threshold income for total country and high-income is estimated about $7,000 which is lower than our expectation. The threshold incomes for low-clean and low-income are even lower, about $540 and $250 for each. Comparing the speed of convergence, we can infer that the speed is fast in total country, America and MENA. At the same time there is no evidence of the convergence in Asia-Pacific, Sub-Saharan Africa and low-income countries. In the near future, there is a high potential that these countries can be heavy emitters. Since they are still on the middle or early stage of economic development global energy policy cooperation is so needed, such as CDM, to minimize the harmful effect on economic growth and to reduce the emissions at the same time.