Micro Droplet Cell을 이용한 국부부식 저항성 평가

金熙山,金星猷 弘益大學校 産業技術硏究所 2005 産業技術 Vol.15 No.-

Mechanical and corrosion properties of 316L stainless steels are degraded with residual δ-ferrite and super ferritic stainless steels containing 30% Cr and 4% Mo are degraded with precipitation of secondary phases such as sigma phase when exposed to temperature of 600℃~820℃. However, the effect of residual δ-ferrite and sigma phase on corrosion resistance is not clearly understood. In this study, the effect of residual δ-ferrite and sigma phase on the localized corrosion in type 316L stainless steels and super-ferritic stainless steels containing 30% Cr and 4% Mo, respectively was examined with an micro droplet techniques and surface analysis. Type 316L stainless steels with δ-ferrite phase have higher passive and active peak current. In addition, the super-ferritic stainless steels with sigma phase have higher corrosion rate in passive zone. The details in mechanisms were described in the paper.

재부동태 속도를 이용한 스테인리스강의 응력부식 민감성 예측

金熙山,金星猷 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-

The recent development of method analyzing repassivation rate using a rapid scratch test and high field conduction model in which log i(t) is proportional to 1/q(t), makes it possible to predict SCC susceptibility more quantitatively, as well as to conduct the test more easily from the viewpoint of cost and timesaving. Since scratched surface is affected by the shape of scratching tip as well as mechanical properties, the inconsistency of scratched surface area having significant influence on the analyzed repassivation rate causes it difficult to distinguish the repassivation rates with a little difference. The validity of the proposed test was confirmed by examination of the effect of the alloy elements(W, Ni) on the repassivation rates of ferritic stainless steels obtained from both rapid scratch tests and the proposed tests.

음향 실험을 통한 영어 모음 발음교정

구희산,김옥경 中央大學校 韓國敎育問題硏究所 2000 韓國敎育問題硏究所論文集 Vol.- No.15

The purposes of this study are to measure and analyse the formant frequency of English vowels pronounced by Korean, and compare with that of English speakers and find the differences of English vowel pronunciation between Korean and American English speakers. At first the definitions of the formant frequency on sound spectrogarm were explained according to the theory of some phoneticians and phonologists. Next we carried out the experiment with selected four Korean women living in Seoul and Kyeonggi Province. We analysed their formant frequency of English vowels /i. I. æuv?α?∂/ with Pitch Works, and as a result, we found that there were differences of English vowel formant frequency between Koreans and American English speakers. In conlusion, we realized the reason of the differences, and suggested the ways that could reduce the differences and enable Koreans to pronounce English vowels similar to those of American English speakers.

C.V.D. 방법에 의한 Cd_0.78Zn_0.22 S박막 성장과 광전기적 특성연구

유상하,이상렬,홍광준,서상석,김혜숙,전승룡,윤은희,문종대 조선대학교 기초과학연구소 1993 自然科學硏究 Vol.16 No.1

We had grown Cd_0.78Zn_0.22S polycrystal thin films on slide substrate using chemical vapour deposition(CVD) method. We measured X-ray diffraction patterns in order to study Cd_0.78Zn_0.22S polycrystal structure. We studied its band gap using transmission curves and photocurrent and also analyzed photoluminescence using configurational coordinate model. We measured Hall effect·on this sample by Van der Pauw method and studied on carrier density and mobility depending on temperature.

중압 배전망에서의 전력선 통신을 위한 OFDM 기법의 성능 분석

임장규,김산해,장희동,이원철,신요안 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-

Recently, PLC (Power Line Communication) on medium voltage power lines have been gaining much attention for high data rate access networking. In this paper, we evaluate the performance of OFDM (Orthogonal Frequency Division Multiplexing) schemes on medium voltage power line channels in the frequency range up to 20 ㎒. We analyze fading characteristics of multi-path channel models for medium voltage power lines, and simulations have been carried out for the OFDM using adaptive bit loading scheme. Simulation results indicate that the OFDM schemes with the adaptive bit loading show good bit error rate performance under harsh medium voltage power lines channel.

백혈병 세포주에 대한 (±)-ar-Turmerone, 자근 및 황금추출물에 의한 항암제의 세포독성 증강효과

이윤영,유관희,김삼용,안병준 충남대학교부설 생명공학연구소 1992 생물공학연구지 Vol.2 No.-

Using the colorimetric [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide](MTT)assay, we evaluated the chemosensitivity of 8 anticancer drugs{vincristine(VCR), vinblastine(VBL), adriamycin(ADR), cisplatin(CPDD), etoposide(VP-16), cytosine arabinoside(ara-C), bleomycin(Bleo) and cyclophosphamide(CYC)} and the cytotoxicity-enhancing effects of (±)-ar-turmerone and the extracts of the crude drugs {Lithospermum erythrorhizon(LE) and Scutellaria baicalensis(SB)}on the above mentioned anticancer drugs against HL-60 and KG-1 cells among 8 anticancer drugs, VCR, VBL, ADR, and CPDD inhibited the growth of both cell lines by more than 50% while VP-16, ara-C, Bleo, and CYC were less effective. (±)-ar-Turmerone had significant inhibitory effects against both cell lines, showing the ID_50 values of 11.730 ㎍/㎖ and 0.292 ㎍/㎖ for HL-60 and KG-1 cells. respectively. But the extracts of LE and SB roots showed no significant cytotoxic effects. According to ID_50 values, the cytotoxicities of VCR, VBL and ADR against HL-60 were enhanced two, eight and three times by mixing (±)-ar-turmerone, five, seven and three times by adding the extract of LE root, and twenty, six and three times by mixing the extract of SB root, respectively. The cytotoxicities of the above mentioned drugs against KG-1 cell were enhanced two, seven and three times by mixing (±)-ar-turmerone, two, three and three times by conbining wilth the extract of LB root, and two, five and two times by adding the extract of SB root, respectively. The cytotoxicity-potentiating effects of (±)-ar-turmerone and the extracts of LE and SB roots against HL-60 cell were greater than KG-1 cell.

Topography of the Submental Artery That Should Be Considered in Bleeding During Dentoalveolar Surgery

Kim, Da-Hye,Won, Sung-Yoon,Choi, Da-Yae,Kim, Hong-San,Jung, Ui-Won,Kim, Hee-Jin,Hu, Kyung-Seok Mutaz B. Habal, MD 2012 JOURNAL OF CRANIOFACIAL SURGERY - Vol.23 No.5

ABSTRACT: The purpose of the present study was to provide precise data regarding the branching pattern of the submental artery, which should be considered in occasions of bleeding during various dentoalveolar surgical procedures of the mandible, such as implant surgeries, tori removal, and iatrogenic injuries.Twenty-six embalmed adult hemifaces from Korean cadavers were used in this study. The vertical distance, horizontal distance, and diameter of the submental artery were measured from the site of the first premolar to the third molar. In cases where there was penetration of the mylohyoid muscle by the main branches of the submental artery, the same items were measured at that point.The vertical distance between the submental artery and the inferior border of the mandible decreased toward the premolar, whereas the horizontal distance from the lingual plate of the mandible increased gradually as it traveled in the anterior direction. The diameter of the artery narrowed slightly toward the premolar. The main branches of the submental artery perforated the mylohyoid muscle in 14 (54%) of the 26 specimens.As a result of this study, the submental artery is located higher from the inferior border and closer to the lingual plate of the mandible in the region of the molar than that of the premolar. Therefore, clinicians should be more careful of bleeding when performing surgery in the molar region compared with the premolar region. Where the mylohyoid muscle is perforated by the main branches of the submental artery, its point of insertion can be observed in diverse locations.

A NOMOGRAM FOR PREDICTING AMYLOID PET POSITIVITY IN AMNESTIC MILD COGNITIVE IMPAIRMENT

Kim, Si Eun,Woo, Sook-Young,Kim, Seon Woo,Chin, Juhee,Kim, Hee Jin,Lee, Byung In,Park, JinSe,Park, Kyung Won,Noh, Young,Ye, Byoung Seok,Yoo, Han Soo,San Lee, Jin,Kim, Yeshin,Kim, Seung Joo,Cho, Soo Hy ELSEVIER SCIENCE B.V. AMSTERDAM 2018 ALZHEIMERS AND DEMENTIA Vol.14 No.7

The Effect of Group Exercise Program on Cognitive Function of Elderly people

Kim, Nyeon Jun,Kim, Moo Ki,Moon, Ok Kon,An, Ho Jung,Shin, Hee Joon,Choi, Yoo Rim,Wang, Jung San,Lee, Joon Hee,Park, Joo Hyun,Kim, Soon Hee International Academy of Physical Therapy Research 2014 Journal of International Academy of Physical Ther Vol.5 No.2

The goal of this study was to assess the effect of a group exercise program on cognitive function of elderly people. Subjects were chosen to be elders with dementia having minor to moderate degrees of cognitive function. Study was started out by randomly dividing the 16 subjects into two groups, each with 8 people; the group exercise group and the control group. The group exercise group performed 8 weeks of group exercise program and general physiotherapy while the control group only performed general physiotherapy. Cognitive function was measured by Korean version mini-mental state examination. The study group's attention and calculation statistically significantly improved but the control group saw no statistically significant change. The group exercise program affected improvement in cognitive function of elderly people with dementia and in particular, was effective for enhancing their attention and calculation.

Anti-inflammatory and Mineralization Effects of ProRoot MTA and Endocem MTA in Studies of Human and Rat Dental Pulps <i>In Vitro</i> and <i>In Vivo</i>

Kim, Do-Hee,Jang, Ji-Hyun,Lee, Bin-Na,Chang, Hoon-Sang,Hwang, In-Nam,Oh, Won-Mann,Kim, Sun-Hun,Min, Kyung-San,Koh, Jeong-Tae,Hwang, Yun-Chan Elsevier 2018 JOURNAL OF ENDODONTICS - Vol.44 No.10

<P><B>Abstract</B></P> <P><B>Introduction</B></P> <P>Few studies have reported direct pulp capping in inflamed pulp conditions. The purpose of this study was to investigate the <I>in vitro</I> and <I>in vivo</I> responses of dental pulp during direct pulp capping using various pulp capping materials in inflamed conditions.</P> <P><B>Methods</B></P> <P>Human dental pulp cells were treated with lipopolysaccharide (LPS) and cultured with Dycal (Dentsply Caulk, Milford, DE), ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland), and Endocem MTA (Maruchi, Wonju, South Korea). The expressions of interleukin (IL)-1β, IL-6, dentin matrix protein 1, and dentin sialophosphoprotein were analyzed through real-time polymerase chain reaction. The maxillary molars of Sprague-Dawley rats were exposed for 2 days. The exposed pulps were capped with Dycal, ProRoot MTA, and Endocem MTA and sealed with resin-modified glass ionomer followed by histologic and immunohistochemical analyses.</P> <P><B>Results</B></P> <P>The expression of IL-1β and IL-6 was increased with LPS and decreased by Dycal, ProRoot MTA, and Endocem MTA. Dentin matrix protein 1 and dentin sialophosphoprotein levels were decreased with LPS and increased after treatment with pulp capping materials.In the <I>in vivo</I> study, inflammation associated with Dycal was higher than that associated with ProRoot MTA and Endocem MTA at week 1, without any significant difference between the 2. At 4 weeks, inflammation was decreased, and mineralization was increased compared with week 1 in all 3 of the materials. At week 1, IL-6 immunoreactivity was strongly expressed. Dycal exhibited stronger immunoreactivity than ProRoot MTA and Endocem MTA. However, the immunoreactivity was decreased in all groups at week 4.</P> <P><B>Conclusions</B></P> <P>Successful direct pulp capping requires more effective pulp capping materials for the treatment of inflamed pulps.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dycal, ProRoot MTA, and Endocem MTA decreased inflammation in inflamed pulp. </LI> <LI> Dycal, ProRoot MTA, and Endocem MTA increased mineralization in inflamed pulp. </LI> <LI> There was no significant difference among Dycal, ProRoot MTA, and Endocem MTA applications to inflamed pulp. </LI> </UL> </P>