솔-젤 법을 통해 제조된 강유전체 (Na,K)NbO₃ 막의 두께에 미치는 PVP의 영향

김대건,유인상,김세훈,김진호,Kim, Dae-Gun,Yoo, In-Sang,Kim, Sae-Hoon,Kim, Jin-Ho 한국재료학회 2012 한국재료학회지 Vol.22 No.12

(Na, K) $NbO_3$ thick film was successfully achieved using a sol-gel coating process with the addition of polyvinylpyrrolidone (PVP) to a metal alkoxide solution. The transparent coating solution, mixed with Nb:PVP = 1:1 in a molar ration, was synthesized by evaporating the solvent to over 62.5 wt%. Additive PVP increased the viscosity of the solution so that the coating thickness could be enhanced. The thickness of the (Na, K) $NbO_3$ film assisted by PVP was ca. 320 nm at the time of deposition; this value is four times thicker than that of the sample fabricated without PVP. Also, due to PVP binding with the OH groups of the metal alkoxide, the condensation reaction in the film was suppressed. The crystalline size of the (Na, K) $NbO_3$ films assisted by PVP was ca. 15 nm smaller than that of the film fabricated without PVP. After the sintering process at $700^{\circ}C$, the (Na, K) $NbO_3$ films were mainly composed of randomly oriented (Na, K) $NbO_3$ phase of perovskite crystal structure, including a somewhat secondary phase of $K_2Nb_4O_{11}$. However, by adding PVP, the content of the secondary phase became quite smaller than that of the sample without PVP. It was thought that the addition of PVP might have the effect of restraining the loss of potassium and that PVP could hold metalloxane by strong hydrogen bonding before complete decomposition. Therefore, the film thickness of the (Na, K) $NbO_3$ films could be considerably advanced and made more crack-free by the addition of PVP.

W-Cu 복합분말의 제조를 위한 기계화학적 공정에서 볼 밀링 시간에 따른 환원거동

김대건,이강원,석명진,김영도,Kim, Dae-Gun,Lee, Kang-Won,Suk, Myung-Jin,Kim, Young-Do 한국재료학회 2003 한국재료학회지 Vol.13 No.3

W-Cu composite powders can be prepared by mechanochemical process, where the $WO_3$-CuO composite powders were mechanically synthesized from the elemental oxide powders and subsequently reduced to W-Cu composite powders. In the present work, reduction behavior of$ WO_3$-CuO composite powders that were synthesized at different milling time was examined in terms of hygrometric analysis. In case of $WO_3$-CuO ball-milled for 20 h, the reaction temperature of CuO\longrightarrowCu became lower than in case of 1 h. Also, the reaction of $WO_3$\longrightarrow$WO_{2.9-2.72}$ and $WO_{2.9-2.72}$ \longrightarrow$WO_2$were shifted to lower temperatures and the peaks were changed to much sharper shape. While the reaction of $WO_2$\longrightarrowW in case of ball-milling for 20 h started at lower temperature, the peak temperature was the same as in 1 h ball-milling. The reduced W particle size was somewhat finer fer 20 h ball-milling. It was considered that the refinement of oxide particles caused by ball-milling process leads to such a change in the reduction behavior.

WO₃-CuO의 수소환원거동에 미치는 볼 밀링의 영향

김대건,심우석,김영도,Kim, Dae-Gun,Shim, Woo-Seok,Kim, Young-Do 한국재료학회 2003 한국재료학회지 Vol.13 No.9

To fabricate W-Cu nanocomposite powder, $WO_3$-CuO powder mixture was high-energetically ball-milled and subsequently hydrogen-reduced. The effect of ball-milling on the hydrogen-reduction behavior of$ WO_3$-CuO was investigated with non-isothermal hygrometric analysis during hydrogen-reduction. Increasing the ball-milling time, the reduction peak temperatures of humidity curves were shifted to low temperature. It was considered that the reduction temperature should be decreased because the specific surface area of each oxide considerably increased with increasing the ball-milling time. In case of ball-milling for 0 h, $WO_3$and CuO were independently hydrogen-reduced and W particles were nucleated on the surface of Cu adjacent to W by CVT. However, in case of ball-milling for 50 h, the aggregates of about 200-300 nm were observed. W particles of size below 30-50 nm were homogeneously distributed with Cu in the aggregates.

토모테라피에서 쌀 볼루스 팬텀의 유용성 평가 : 팬텀연구

김대건(Dae-Gun Kim),정재홍(Jae-Hong Jung) 대한방사선과학회(구 대한방사선기술학회) 2021 방사선기술과학 Vol.44 No.6

The purpose of this study was to evaluate the usefulness of the rice bolus for upper-lower extremity radiation therapy by Tomotherapy. The computed tomography images were obtained for air, water, and rice bolus. The average and standard deviation of the Hounsfield unit (HU) were measured for image evaluation. The conformity index (CI) and homogeneity index (HI) were calculated for dose distribution of the planning target volume (PTV) which was treated by direct mode with gantry angle (90 and 270 angle). The point dose of a total of ten axial planes was measured to confirm the different regions. The mean of HU was -999.72 ± 0.72 at the air. The water and rice bolus were -0.13 ± 1.65 and -170 ± 27.2, respectively. The CI (HI) of PTV was 0.96 (1.36) at the air. 0.95 (1.04) at the water bolus, and 0.95 (1.04) at the rice bolus. The maximum dose for air was 136 cGy which is about 32% higher than 103 cGy for water and 104 cGy for rice bolus. There was a statistical difference for point dose between air and water including rice bolus (p=0.04), however, no statistical difference between water and rice bolus (p=0.579).The rice bolus phantom for extremities radiation therapy could be not only the optimized dose distribution but also the convenience and equipment safety at Tomotherapy. However, additional research will be necessary to more accurately verify the clinical usefulness of rice bolus phantom due to not enough examination.

소득분위에 따른 중고령층의 사회참여 영향요인 연구

김대건(Kim Dae Gun) 호남대학교 인문사회과학연구소 2018 인문사회과학연구 Vol.60 No.1

본 연구는 중고령층의 소득에 따른 내부적 이질성에 기반하여 사회참여에 영향을 미치는 요인을 소득분위에 따라 확인한 연구이다. 중고령층 인구집단을 소득에 따라 4분위로 나누고 선행연구에 따라 제시된 사회참여 영향요인의 유효성을 확인하였다. 분석자료는 고령화연구패널 5차자료를 사용하였다. 분석에는 50세 이상 65세 미만의 2,791사례가 투입되었다. 분석결과 대부분의 사회참여 영향요인은 전체 중고령층집단에서 유의한 영향을 미치는 것이 확인되었다. 그러나 소득분위집단으로 구분하여 분석한 결과 소득이 높아짐에 따라 변수의 영향력은 순차적으로 상실되는 경향을 보이는 것으로 나타났다. 특히 가장 높은 소득수준을 보인 집단에서는 교육수준과 건강상태를 제외한 모든 변수가 설명력을 상실하는 것을 확인하였다. 본 연구는 분석결과에 기반하여 중고령층의 사회참여를 유도하는 다양한 정책들이 중고령층 개인의 소득수준 및 욕구에 따라 개별적으로 적용될 수 있는 정책적 탄력성을 가져야 함을 함의로 제시하였다. The purpose of this study is to investigate the factor which affects the civic engagement based on the internal heterogeneity according to the middle and old-aged people s income. This study was to divide the population group of middle and old-aged people according to the income in quartile and to confirm the effectiveness on the correlates of civic engagement suggested in preceding study. As for the analysis data, this study was to use Korean Longitudinal Study of Ageing(KLoSA). The result of this research is may be summed up as follows. This study has shown that the correlates of most of civic engagement had significant effect on the group of total middle and old-aged people. However, as a result of analyzing it by dividing it into the income distribution group, this study has found out that the influence of variables showed a tendency to be lost in consecutive order as income levels rose. In particular, at the group which showed the highest income level, the whole variable except the education level and health status lost its explanation power. Based on the analysis result, this study was to implicatively suggest that various policies which induced the civic engagement for the middle and old-aged people should have policy resilience which could be applied individually according to the individual income level and needs for the middle and old-aged people.

지상파 데이터방송 서비스를 제공하기 위한 IPTV 시스템에 관한 연구

김대건(Kim Dae-Gun),이연(Lee Yean),최락권(Choi Rack Kweon),송호은(Ho-Eun Song),이상수(Lee Sang Soo) 한국통신학회 2006 한국통신학회 학술대회논문집 Vol.2006 No.7

온톨로지 기반 상황 인식 추천 서비스 모델링

김대건(Kim Dae Gun),이형도(Lee Hyung Do),윤희용(Youn Hee Yong) 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.2

최근 GPS나 각종 센서를 이용한 스마트폰과 무선네트워크 같은 여러 가지 모바일 기술이 성장하면서 언제 어디서나 원하는 서비스를 제공해 줄 수 있는 유비쿼터스 환경이 현실화되고 있다. 특히 사용자의 위치를 자동으로 인식하고 사용자의 기호를 바탕으로 장소를 추천해주는 추천 정보 서비스는 매우 유용한 서비스라 할 수 있다. 그러나 정보의 과부하에 비해 사용자에게 적절한 서비스를 제공해 줄 수 있는 모바일기기는 제한된 성능과 한계를 가진다. 따라서 사용자의 현재 상황에 비추어 적절한 정보를 추천하는 기술이 필요하다. 이들 분야의 핵심 요소인 온톨로지의 필요성 또한 커지고 있으나, 현재 실용적인 온톨로지가 구축된 경우를 찾아보기는 어렵다. 실용적인 온톨로지를 구축하기 위해서는 도메인의 지식을 개념화할 수 있는 도메인 지식 전문가와 이를 구조화할 수 있는 온톨로지 설계 전문가가 필요하다. 본 논문에서는 온톨로지의 모델을 사용하여 상황에 맞춘 추천을 제공하는 서비스를 제안한다.

노인일자리사업 연구경향 분석

김대건(Dae-Gun Kim) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.4

본 연구의 목적은 노인일자리사업을 주제로 하는 학술 연구의 경향을 확인하는 것이다. 이를 위해 학술검색 엔진을 활용한 키워드 검색으로 연구 결과를 수집하여 총 133개 연구를 분석 대상으로 선정하였다. 또한 분석자료의 내용을 비교검토하는 기술적 연구방법(descriptive study)의 내용분석(content analysis) 방법을 활용하여 각 연구의 출처, 연구 주제, 연구방법, 연구 대상 등 연구 경향을 분석하였다. 분석결과 노인일자리사업을 연구 주제로 한 학술연구에서 사업 참여노인을 연구대상으로 하여 사업의 효과를 확인하는 양적 연구가 지금까지 가장 주도적인 연구 유형으로 확인되었다. 반면 노인의 노동이나 사회적 역할 등을 노인일자리사업과 연결하여 이해하려는 철학적·윤리적 검토가 연구로 나타난 경우는 상대적으로 매우 적었다. 본 연구에서는 이 같은 연구 경향에 기반하여 노인일자리사업 내 다양한 참여 주체들뿐만 아니라 사업 참여 노인까지도 연구의 주된 관심사에서 제외된 상황을 비판하고 후속 연구에서는 이 같은 경향에서 탈피할 필요가 있음을 제안하였다. The purpose of this study is to identify trends of academic research on senior employment projects. For this aim, research results were collected from keyword searches utilizing academic search engines, and a total of 133 research studies were selected as analysis subjects. Then, we analyzed research trends such as sources, research themes, research methods, and research subjects using the content analysis method,. According to the results, the leading type of senior employment research was quantitative research that confirmed the effects of projects by targeting the elderly participants. On the other hand, there were relatively few cases in which philosophical and ethical reviews were used to understand the labor and social roles of the elderly in connection with senior employment projects. Based on these research trends, this study criticized the situation where not only a variety of main participants but also the elderly taking part in the senior employment project were excluded from the main concern of research and suggested that it was necessary for follow-up studies to emerge from these trends.

전통 등화 기구를 응용한 조명디자인 연구 - 미니멀리즘의 조형적 특징을 중심으로 -

김대건 ( Kim Dae Gun ) 한국상품문화디자인학회(구 한국패키지디자인학회) 2021 상품문화디자인학연구 Vol.65 No.-

본 논문은 우리나라의 전통 등화 기구 중 조선시대의 촛대를 전통적 소재로 활용하여 조선시대 등화 기구의 시대적 배경으로부터 나타나는 외형적 형태의 특징을 미니멀리즘의 조형요소와 접목하고 현대적으로 재해석한 조명 디자인 개발에 대한 연구이다. 우리나라의 전통 등화 기구의 역사는 삼국시대부터 시작된 것으로 추측된다. 청동 제작 기술이 매우 발달한 고려시대와 철을 단련하여 일상생활에 유용한 도구를 만들어 사용하게 된 조선시대에는 다양한 전통 등기가 등장하게 된다. 조선시대의 등기는 통일신라시대와 고려시대에 등기로부터 나타나는 불교의 영향과 귀족적이며 화려한 특징과 달리 다양한 계층의 사용으로 인해 간편하고 실용적인 측면의 특징을 보인다. 조선시대 등화기구 중 촛대에는 이전 시대에 나타나지 않았던 기능적, 구조적인 요소가 접목되어 실용성을 나타나는 조형적 특징을 갖추고 있다는 것을 확인할 수 있다. 조선시대의 촛대가 가지는 구성요소 중 기능적, 구조적 특징은 특정목적이 아닌 일상생활에서의 사용되며 실용성을 겸비한 확장성을 가진다는 점에서 매우 흥미롭다. 이에 본 연구자는 조선시대의 촛대를 미니멀리즘의 단순성, 명료성, 공간성 등의 개념과 접목하여 현대적 조형으로 표현하고자 한다. 우리나라의 전통등화 기구의 역사와 발달을 통해 조선시대 촛대의 형성과정을 파악하고 조형적 특징을 분석하여 조선촛대의 형태에서 나타나는 구조를 미니멀리즘의 요소와 접목시켜 디자인 전개를 진행하였다. 조선시대의 촛대를 분석하고 재해석하여 미니멀리즘이 조형적 특징 중 단순성, 명료성, 공간성과 접목하여 현대적 조명으로 디자인, 제작하였다. 이후 전통 등화 기구를 연구, 분석하여 다양한 조명디자인을 지속적으로 개발하고자 한다. The traditional lamp device has developed as the traditional lighting of the nation under the influence of the times. The discovery of fire in prehistoric times was used for heating and cooking purposes and is the beginning of artificial lighting instead of the natural sunlight. Afterwards, lamps using oil from animals or plants as fuel appeared, followed by the appearance of candlesticks as wax candles using bee wax were used. It is assumed that the history of Korea’s traditional lighting device has begun in the period of the Three States. Various traditional lamps appeared during the Koryo Dynasty, when the bronze production technology was highly developed, and the Joseon Dynasty, when iron was tempered to make and use useful tools for everyday life. Unlike the Koryo Dynasty, which formed an aristocratic and glamorous culture under the influence of Buddhism, the simple and practical lamp devices were created during the Joseon Dynasty. The artistic tendencies of the Joseon Dynasty diverge from the glamorous culture centered on aristocrats and represent the social features that prioritized the harmony of moderation in terms of ascetic ethics of Confucian thinking and simple and credible aspects. This artistic tendency was determined to be similar to minimalism, which began with the exploration of the root of objects with minimal expression by eliminating unnecessary elements. This is the study on the lighting design applying traditional lamp device and the development of lighting devices that identifies the features of traditional lamp devices and applies the formative elements of minimalism. By analysing the relationship between candlesticks and minimalism in the Joseon Dynasty, the modern use of traditional materials in the field of lighting design was derived, and the research and development of various lighting designs using traditional materials is expected to continue.

방사선치료 환자를 위한 온라인 교육 동영상 분석

김대건(Dae-Gun Kim),정재홍(Jae-Hong Jeong) 대한방사선과학회(구 대한방사선기술학회) 2022 방사선기술과학 Vol.45 No.1

This study aimed to analyze educational understanding and satisfaction by survey including for the online educational videos by used online platform (YouTube) which provide resolve patient’s questions, require attention and treatment information for a patient with radiation therapy. Video viewing analysis was used by YouTube studio. The survey was analyzed general properties (age, academic ability, disease, and watched of no watched videos) and educational understanding and satisfaction for two groups as no watched and watched patients. The views number was 60% at the female higher than 40% at the male. Based on the standard viewing time (hours), the non-subscription rate was 86.7%. The device type mostly used the mobile phone (82.8%). The viewership of educational videos was lower as the age increased and the academic ability decreased in the survey. The educational understanding increased by 22% at watched group as 4.15 point from at no watched group as 3.4 point (p<0.001), and the educational satisfaction increased by 15.8% at watched group as 4.25 point from at no watched group as 3.67 point (p<0.01). The correlation of understanding (r=0.761) and satisfaction (r=0.767) was high for both no watched and watched groups (p<0.01). The online educational videos increased educational understanding and satisfaction for the patient with radiation therapy. Our study could be used references data for improving the quality of medical services.