분말야금법으로 제조된 FeSi₂ 열전특성 화합물의 열처리 시간에 따른 미세조직과 상변화

박경태,신진교,홍순직,천병선,Park, Kyoung-Tae,Shin, Jin-Gyo,Hong, Soon-Jik,Chun, Byong-Sun 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.6

In this study, $FeSi_2$ as high temperature performance capable thermoelectric materials was manufactured by powder metallurgy.The as-casted Fe-Si alloy was annealed for homogenization below $1200^{\circ}C$ for 3 h. Due to its high brittleness, the cast alloy transformed to fine powders by ball-milling, followed by subsequent compaction (hydraulic pressure; 2 GPa) and sintering ($1200^{\circ}C$, 12 h). In order to precipitate ${\beta}-FeSi_2$, heat treatment was performed at $850^{\circ}C$ with varying dwell time (7, 15 and 55 h). As a result of this experiment thermoelectric phase ${\beta}-FeSi_2$ was quickly transformed by powder metallurgical process. There was not much change in powder factor between 7h and 55h specimens.

Tissue response of Pro-Root^® MTA with rhBMP-2 in pulpotomized rat teeth

박경태,양원경,고현정,김미리,Park, Kyung-Tae,Yang, Won-Kyung,Ko, Hyun-Jung,Kim, Mi-Ri The Korean Academy of Conservative Dentistry 2007 Restorative Dentistry & Endodontics Vol.32 No.5

이 실험의 목적은 백서에서 치수절단술을 시행시 MTA 시멘트 단독 사용군과 rhBMP-2 혼용 사용군 간의 조직 반응을 비교하기 위함이다. 32마리의 건강한 백서의 상악 양쪽 제 1 대구치를 사용하였다. 치수강을 개방한 후에 지혈을 시행하고 우측 제1 대구치에는 대조군으로 MTA 시멘트 1.2 g을 사용하여 치수절단면을 수복하였고, 좌측 제 1대구치에는 MTA 시멘트 1.2 g에 rhBMP-2 $1\;{\mu}g$을 첨가하여 치수절단면을 수복하였다. 그 후 광중합 글래스 아이오노머 시멘트로 충전하였다. 백서는 각 각 16마리씩 2주, 7주 뒤에 희생시키고, 병리조직표본을 제작하였다. 통계 처리는 SPSS-WIN 12.0 프로그램을 이용하여 student t-test를 시행하였다 (p < 0.05). 염증소견은 7주군보다 2주군에서 더 심하였으나, 통계적으로 유의하지는 않았다 또한 rhBMP-2를 첨가한 군이 MTA 단독 사용군보다 염증 소견이 적어 보였으나, 역시 통계적으로 유의하지는 않았다. 결론적으로 MTA 시멘트 치수 절단술 시행시 MTA 단독 사용군과 비교시 MTA 시멘트에 rhBMP-2의 첨가하는 것은 별다른 차이가 없었다. The purpose of this study was to investigate whether rhBMP-2 (BMP2) could induce synergistic effect with $Pro-Root^{(R)}$ MTA (MTA) in pulpotomized teeth in the rats. Healthy upper first molars from thirty-two, 10 weeks old, Sprague-Dawley rats were used for this investigation. The molars were exposed with round bur, and light pressure was applied with sterilized cotton to control hemorrhage. 1.2 grams of MTA cement was placed in right first molars as a control group. In left first molars, $1\;{\mu}g$ of BMP2 was additionally placed on exposed pulps with MTA. All cavities were back-filled with light-cured glass-ionomer cements. The rats were sacrificed after 2 weeks and 7 weeks, respectively. Then histologic sections were made and assessed by light microscopy. Data were statistically analyzed via student t-test with SPSSWIN 12.0 program (p < 0.05). Inflammation observed in 2 weeks groups were severe compared to the 7 weeks groups. But the differences were not statistically significant. BMP2-addition groups had less inflammation than MTA groups in both periods, though these differences were also not statistically significant. In conclusion, the combination of BMP2 and MTA showed no differences with MTA only for pulpotomy of rat teeth.

자유 공간 모델과 하타 모델을 이용한 구간별 경로 손실 모델 설정에 관한 연구

박경태,조형래,Park, Kyung-Tae,Cho, Hyung-Rae 한국융합신호처리학회 2011 융합신호처리학회 논문지 (JISPS) Vol.12 No.3

In this paper, we obtained the path loss characteristics in the 850 MHz for Russia area by using the free space path loss model and Okumura-Hata path loss model. In order to extract the additional path loss model parameter from the new Russian regional properties, the mean square error technique is used to obtain the correction factor. According to the obtained correction factor, the differences for the free space and Hata path loss model are 17, 6 dB in the 5 ~ 10 Km, 28, 14 dB in the 10 ~ 15 Km, and 35, 18 dB in the 15 ~ 20 Km. By applying the correction factors, the appropriate partial path loss models for the measured Russain area are proposed. 본 논문에서는 850 MHz 이동 통신 대역에서의 자유공간 빚 오쿠무라-하타 모델 적용하여, 기지국 설치 대상 지역인 러시아 지역의 경로손실 특성을 구하였다. 기존 경로 손실 모델에 측정 대상 지역인 러시아 PNG 지역의 특성을 추가하기 위하여, 최소 자승 평균 기법을 적용하여 측정 지역의 경로 손실 보정값을 구하였다. 이렇게 구한 보정값을 이용하면, 자유 공간 경로 손실 및 하타 경로 손실 설정값과 실제 측정값의 차이가 5 ~ 10 Km 구간에서는 각각 17, 6 dB, 10 ~ 15 Km 구간에서는 각각 28, 14 dB, 15 ~ 20 Km 구간에서는 각각 35, 18 dB의 측정 대상 지역에 대한 구간별 경로 손실 모델을 설정할 수 있었다.

지르코늄의 제조(製造)와 재활용기술(再活用技術)

박경태,김승현,홍순익,최미선,조남찬,유환준,이종현,Park, Kyoung-Tae,Kim, Seung-Hyun,Hong, Soon-Ik,Choi, Mi-Sun,Cho, Nam-Chan,Yoo, Hwan-Jun,Lee, Jong-Hyeon 한국자원리싸이클링학회 2012 資源 리싸이클링 Vol.21 No.5

Zr은 고온에서의 높은 치수안정성, 내식성은 물론 낮은 중성자 흡수단면적을 지녀 원자력산업용 소재 중 1차 방사능 차폐재인 핵연료 피복관으로 사용되며 현재까지 다른 소재로 대체 불가능하다. 하지만 Hf을 정제한 Zr sponge 제조기술은 미국, 프랑스, 러시아만 가지고 있어 원자력의존도가 높은 한국에서는 국가전략물자로 분류 철저히 관리되고 있다. 국내 유통되는 Zr의 대부분은 원자력산업에 사용되어 지며 유통구조는 정제된 Zr합금을 국외로부터 수입하여 tube로 가공 후 핵연료집합체로 제조되고, 그 외 소량이 합금첨가원소 및 폭약재 등 고부가가치 일반산업에 사용된다. 본 논문에서는 Zr 제조기술에 대한 현재산업현황 및 정련기술을 살펴보고, 최근 연구되고 있는 Electrolytic reduction process와 Molten oxide electrolysis와 같은 신 제련기술에 대한 소개 및 Zr recycling의 전반적인 기술소개도 포함하였다. Zirconium is one of the most important material used as cladding of fuel rods in nuclear reactors because of its high dimensional stability, good corrosion resistance and especially low neutron-absorbing cross section. However, Hf free nuclear grade Zr sponge is commercially produced by only three countries including USA, France and Russia. So, Zr has been thoroughly managed as a national strategic material in Korea. Most of the zirconium is used for Korean nuclear industry as nuclear fuel cladding materials manufactured from Hf free Zr alloy raw material. Also, there are some other applications such as alloying element and detonator. In this review, zirconium production and recycling technologies have been reviewed and current industrial status was also analyzed. And recent achievements in innovative reduction technologies such as electrolytic reduction process and molten oxide electrolysis were also introduced.

전자빔 용접된 Cu / STS 304강의 미세조직에 관한 연구

박경태,김인호,백준호,천병선,Park, Kyoung-Tae,Kim, In-Ho,Baek, Jun-Ho,Chun, Byung-Sun 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.2

According to the research report for the recent a few years, the dissimilar welding of Cu and STS 304 alloy have been presented that a weldability is very poor. This article present a study on Lap joint by Electron beam welding dissimilar materials. The weld metals was constituted between pure copper and STS 304 steel. The experiment was performed with 125mA welding current, 520mA focusing current. The Vacuum condition of chamber is 5${\times}$10-5torr and welding speed is 300mm/min. Showing the bead shape of weld metal, the thickness of the stainless 304 using as the protect materials is 3mm and the thickness of a copper is 15mm. The analysis about the microstructure were carried out in which it was observed with SEM. The results showed that complex heterogeneous fusion zone microstructure characterized both by rapid cooling and mixing of the molten metal, however the liquation crack was formated in the fusion line.

이동 통신 망에서 측정하여 계산된 경로 손실의 급격한 변동 위치 추출 방법

박경태,배성혁,Park, Kyung-Tae,Bae, Sung-Hyuk 한국융합신호처리학회 2014 융합신호처리학회 논문지 (JISPS) Vol.15 No.1

이동 통신망의 기지국과 이동국 사이의 거리 차로 인하여 발생하는 경로 손실 데이터를 분석하였다. 본 논문에서는, 측정된 수신 신호세기(RSSI)로부터 송수신기 거리 차이에 따른 경로 손실을 계산하여 이를 그래프로 표시하고, 평균한 데이터를 이용하여 기존의 경로 손실 모델들(자유공간 모델, 지면반사파 모델, 하타 모델, ${\ldots}$)과 그래프를 동시에 그려서 비교하였다. 2 Km, 1 Km, 0.5 Km 간격으로 평균한 경로 손실 데이터에 대한 표준 편차를 구해 보니, 각각 2.29 dB, 3.39 dB, 4.75 dB가 되었다. 본 논문에서는 거리별로 계산된 경로 손실 평균값들의 미분 값을 구하여, 앞에서 구한 경로 손실 표준 편차의 1 또는 2배수를 초과하여 변동하는 위치를 찾아내는 방법을 제안 하였다. 이렇게 제안한 방법을 적용하여 분석한 결과, 송수신기 사이에서 손실이 급격하게 발생하는 지점이, 2 Km 간격으로 경로 손실을 평균한 경우에는 5 지점, 1 Km 간격으로 평균한 경우에는 7 지점, 0.5 Km 간격으로 평균한 경우에는 19 지점이 됨을 알 수 있었고, 구체적인 위치를 파악하는 성과를 얻었다. The path loss data was re-calculated according to the distance between the base station and a mobile station in the mobile telecommunications network. In this paper, the averaged path loss data was plotted with the conventional path loss models(free space, plane earth, Hata model ${\ldots}$). The standard deviations for the 2 Km, 1 Km, 0.5 Km-interval averaged path loss were 2.29 dB, 3.39 dB, 4.75 dB, respectively. Additionally, the derivative values for the 2 Km, 1 Km, 0.5 Km-interval averaged path loss were evaluated to find the positions with more than 1 times or 2times of the standard deviation. The situations with the sharply fluctuated path loss were calculated to 5 positions in the 2 Km interval, to 7 positions in the 1 Km interval, to 19 positions in the 0.5 Km interval, respectively. And, the exact distances between the base station and a mobile station were found with the sharply fluctuated path loss.

조직배양을 이용한 가지고비고사리의 전엽체와 포자체 대량번식을 위한 배양조건

박경태,장보국,이철희,Park, Kyungtae,Jang, Bo Kook,Lee, Cheol Hee 한국식물생명공학회 2019 식물생명공학회지 Vol.46 No.2

본 연구는 다양한 분야에서 활용이 가능한 봉의꼬리과 가지고비고사리[Coniogramme japonica (Thunb.) Diels]의 전엽체와 포자체의 대량번식을 위한 적정 배양방법을 구명하고자 수행되었다. 전엽체 증식을 위해 기내에서 발아하여 계대배양한 전엽체를 재료로 사용하여 1/4-1배로 조절한 MS 배지와 Knop 배지에 10주간 배양한 결과, 1MS 배지에서 전엽체의 생체중이 14.5 g으로 가장 많이 증가하였다. 이후 1MS 배지에 sucrose와 활성탄, 질소급원의 농도를 다르게 조절하여 8주간 배양한 결과, 3%의 sucrose 농도에서 전엽체의 생체중이 10.8 g으로 증식률이 가장 좋았다. 활성탄의 경우 네 처리구가 8.8 ~ 10.8 g 범위로 농도에 따른 유의적인 차이를 보이지 않았다. 질소급원은 ${NH_4}^+:{NO_3}^-$의 비를 1:2로 하여 30, 60, 120 mM의 농도로 첨가한 결과, 세 처리구 모두 생체중에 유의한 차이가 없었으며 비슷한 수준으로 증가하였다. 토양종류에 따른 포자체의 형성을 실험한 결과, 원예상토와 마사토를 2:1(v:v)로 혼합한 토양에서 228.0개로 가장 많은 포자체가 형성되었다. 반면에 피트모스와 마사토를 2:1(v:v)로 혼합한 토양을 제외하고 피트모스가 첨가된 토양에서는 포자체가 형성되지 않았다. This study was conducted to investigate the optimal culture method for gametophyte and sporophyte propagation in Coniogramme japonica (Thunb.) Diels, which can be used in various fields. The propagation of prothallus were cultured in 1/4 - 1 Murashige and Skoog medium and Knop medium for 10 weeks. The results indicated that the fresh weight of prothallus was the highest (14.5 g) in 1MS medium. Subsequently, various concentrations of sucrose, activated charcoal and nitrogen source were also added to 1MS medium and cultured for 8 weeks. The results provided that the sucrose concentration was 3% and the fresh weight of prothallus was the highest 10.8 g. According to the concentration in the range of 8.8 ~ 10.8 g, in the case of activated charcoal, the four treatments showed no significant difference. The nitrogen source was added at a concentration of 30, 60 and 120 mM with the ratio of ${NH_4}^+:{NO_3}^-$ being 1 : 2. As a result, the fresh weight of all treatments increased to similar level but there was no significant difference. We investigated sporophyte formation according to soil type and the highest number of sporophytes at 228.0 was formed in soils mixed with horticultural substrate and decomposed granite at 2 : 1 (v : v). On the other hand, sporophyte was not formed in soils containing peatmoss except for the one with peatmoss and decomposed granite at 2 : 1 (v : v).

온라인커뮤니티 특성에 의한 관계품질이 충성도에 미치는 영향

박경태(Kyong Tae Park) 한국관광연구학회 2014 관광연구저널 Vol.28 No.3

The purpose of this research is to analyze influence of relation quality on loyalty in constructing relationship withcustomers, as well as to suggest a basic material for operating effectively and activating online community. In thiscontext, the knowledge what the meaning of community characteristic is in case of coffee bars under onlineenvironment in Busan-si and Kyungsangnam-do becomes a research background. For questionary survey, 300questionaries were distributed during 13th∼27th of may. 2013 and then 267 of them was applied to empiricalanalysis. For data processing, spss win version 18.0 statistic package program was adopted. The verification wasconducted through frequency analysis, reliability analysis, factor analysis, regression analysis. Taking a close look atwhat influence online community characteristic has on relation quality, the result are summarized as follows. First,items of mutual interaction, information provision, community awareness, which are included in one communitycharacteristic, have a significant influence on a factor of trust, which is included in relation quality. Second, items ofpleasure, community awareness, which are included in community characteristic, have a significant influence on afactor of satisfaction, which is included in relation quality. And third, when examining what influence relationquality has on loyalty, it is revealed that factors of trust and satisfaction, which are included in relation quality, havea significant influence on loyalty.

플라이애시와 스테인리스 스틸 AOD 슬래그를 활용한 폼 블록의 역학적 특성

박경태(Park, Kyoung Tae),강철현(Kang Chul Hyun),라정민(Ra, Jeong Min),최영철(Choi, Young Cheol) 한국콘크리트학회 2018 한국콘크리트학회 학술대회 논문집 Vol.30 No.2

긴잎도깨비쇠고비의 대량번식을 위한 적정 배양조건

박경태(Kyungtae Park),장보국(Bo Kook Jang),이기철(Ki Cheol Lee),이철희(Cheol Hee Lee) 한국원예학회 2018 한국원예학회 학술발표요지 Vol.2018 No.10