로타 초음파 검사에서의 초음파 평가 결함크기와 실결함 크기와의 관계

성운학,김정태,박윤식 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1

In order to evaluate the reliability of rotor forgings, it is very important to know the actual size of the defects in the rotor forgings. The determination of the defect size requires the accurate non-destructivc measurement. However, there may be some differences between the reported size with the ultrasonic non-destructive testing method and the actual size of defects. These differences may be a severe cause of errors in evaluation of rotor forgings. So, the calculated size with "Master Curve" considering safety factor, which is usually larger than the reported size, has been used in evaluation of rotor forgings. The relation between EFBH (Equivalent Flat Bottom Hole) size measured by non-destructive method and the actual size by destructive method in many rotors manufactured at Doosan was investigated. In this investigation, "Master Curve" compensating the differences between UT reported size and actual size of defects in our rotor forgings was obtainable. The applicability of this "Master Curve" as a way of calculating the actual defect sizc was also investigated. For the evaluation of rotor forgings, it is experted that this "Master Curve" may be used to determine the accurate actual size of defects.

와이어 매시 레인포스트 시멘트에 관한 硏究

閔丙亨,朴雲龍,金勇熙,鄭昌植 동아대학교 공과대학 부설 한국자원개발연구소 1985 硏究報告 Vol.9 No.2

This study has been performed on the selective method of materials for MRC and the various mechanical tests through the testing manufacture of MRC pontoon. And we have attempted the enlargement of use by it's merits.

전기경련치료(ECT)시 뇌파의 비선형 분석 : 단일증례 연구 A Single Case Study

강웅구,이운철,정선주,윤세창,조맹제,이상훈,김용식 大韓神經精神醫學會 1999 신경정신의학 Vol.38 No.5

연구목적 : 비선형 분석을 통해 전기경련 치료(ECT)의 적절성 및 효과를 판정할 수 있는 새로운 변인을 추출해 낼 가능성을 탐색하기 위하여 한 여성 우울증 환자에서 ECT중 기록한 뇌파의 단일증례 분석을 하였다. 방 법 : 1주일 간격을 둔 두 ECT 회기에서 치료전 안정상태, 마취후-경련전상태, 경련상태, 경련후 뇌파억제상태, 치료후 안정상태의 다섯 상태에 따른 뇌파를 디지털 기록한 데이터를 분석하였다. 결 과 : 분석의 결과 1) 뇌파가 10차원 이하 저차원의 결정론적 성질을 가지고있으며 2) 뇌파는 비정상적(non-stationary)이지만 비선형 지수들이 각 상태 뇌파를 안정적으로 구분해 줄 수 있고 3) ECT 회기의 진행에 따라 경련중 뇌파의 결정론적 성질이 증가하며 4) ECT 회기의 진행에 따라 치료전후 안정상태 뇌파의 최대발산지수(PLE) 및 상관차원이 증가한다는 사실을 관찰할 수 있었다. 결 론 : 단일증례에 대한 다양한 비선형 분석의 결과는 ECT의 치료효과를 정량화할 수 있는 변인으로서 PLE, 상관차원 등 비선형 변수들이 사용될 수 있을 가능성을 제시한다. Objectives : In order to search for new parameters for the evaluation of the adequacy of electroconvulsive therapy(ECT), the authors performed a non-linear analysis of electroencephalogram(EEG) recorded during the course of electroconvulsive therapy(ECT) in a single female patient with depression. Methods : Digitized EEG recordings from two ECT sessions spaced one week were analyzed at five different stages ; pretreatment stable, postanesthetic-preictal, ictal, postical suppression and posttreatment stable stages. Results : Our analysis showed that 1) EEG signals had low dimensional(below 10 dimensions) deterministic characteristics 2) although EEG was nonstationary signal, non-linear parameters could reliably differentiate between various stages we examined. 3) the deterministic property of ictal EEG increased according to the progression of sessions and 4) the primary Lyapunov exponent(PLE) and correlation dimension of pre- and post-treatment stable stage EEG increased according to the progression of sessions. Conclusion : In this single case study, results of various non-linear analyses suggested that non-linear variables extracted from EEG recordings during ECT may have utilities as tools for the quantitative evaluation of ECT.

한국어 대용량 음성인식에서의 효율적인 시간 감축에 관한 연구

장춘서,이기수,신윤식,임은기,김병만,김현수 금오공과대학교 산업기술개발연구원 2000 産業技術開發硏究 Vol.16 No.-

In this paper a time reduction algorithm for large vocabulary speech recognition system has been studied. TDNN(Time Delay Neural Network) was used to classify vowel using phonetical fetures. To increase performance of vowel classification, modular TDNN architecture associated with 2 states input layer has been suggested.

Synthesis and Characterization of Organic Light-Emitting Copolymers Containing Naphthalene

Kim, Jung-Sik,Heo, Jun,Kang, Peng-Tao,Kim, Jin-Hak,Jung, Sung-Ouk,Kwon, Soon-Ki,Kim, Un-Kyung,Kim, Yun-Hi The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.2

Conjugated PPV-derived block copolymers containing 2-ethylhexyloxynaphthalene unit were synthesized and characterized in this study. The resulting polymers were soluble in common organic solvents and showed good thermal stabilities, The weight-average molecular weights ($M_w$) of the copolymers ranged from 246,000 to 475,000 with PDIs of $1.3{\sim}2.1$. The optical properties of these polymers, measured both in a chloroform solution and on a film, showed a maximum absorption at $405{\sim}476\;nm$ for Copolymers $I{\sim}VIII$. In the PL spectra, Copolymers $I{\sim}VIII$ showed maximum peaks at $510{\sim}566\;nm$. The HOMOs, LUMOs and band gaps of the PPV derivatives of Copolymers $I{\sim}VIII$ were $5.30{\sim}5.77$, $3.04{\sim}3.24$, and $2.5{\sim}2.2\;eV$, respectively, The multi-layered, light-emitting diodes of ITO/PEDOT/copolymers/LiF/Al exhibited turn-on voltages of $6{\sim}2.5\;V$ Copolymer VIII exhibited the maximum brightness of $3.657\;cd/m^2$. Particularly, Copolymer VII, with an identical composition of MEH-PPV and naphthalene-PPV, showed a maximum luminance efficiency and power efficiency of 2,63 cd/A and 1.06 lm/W, respectively.

Highly efficient and highly stable terpolymer-based all-polymer solar cells with broad complementary absorption and robust morphology

Kim, Aesun,Park, Chang Geun,Park, Su Hong,Kim, Hyung Jong,Choi, Suna,Kim, Young Un,Jeong, Choel Hun,Chae, Weon-Sik,Cho, Min Ju,Choi, Dong Hoon The Royal Society of Chemistry 2018 Journal of materials chemistry. A, Materials for e Vol.6 No.21

<P>A novel conjugated terpolymer referred to as Ter-3MTTPD was successfully synthesized using 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-<I>b</I>:4,5-<I>b</I>′]dithiophene as a donor and methyl thiophene-3-carboxylate (3MT) and 5-(2-ethylhexyl)-4<I>H</I>-thieno[3,4-<I>c</I>]pyrrole-4,6(5<I>H</I>)-dione (TPD) as acceptor units to investigate the effects of the terpolymer structure on the optical and electrochemical properties. The performance of an all-polymer solar cell (all-PSC) was comprehensively examined by blending the terpolymer with 2,7-bis(2-hexyldecyl)-4-(selenophen-2-yl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2<I>H</I>,7<I>H</I>)-tetraone (NDI-Se). The as-cast blend film of Ter-3MTTPD:NDI-Se exhibits the highest power conversion efficiency of 7.66% in the all-PSC. This was further supported by the results of time-resolved photoluminescence (TRPL) in Ter-3MTTPD:NDI-Se blend film states which yielded the highest PL quenching efficiency (90%) resulting from the shortest average lifetime, <I>τ</I>ave of ∼67 ps, much smaller than those of the two binary copolymer blend films (<I>e.g.</I>, <I>τ</I>ave = 194 ps and 149 ps, respectively, for Co-3MT:NDI-Se and Co-TPD:NDI-Se). In addition, for an as-cast blend film of Ter-3MTTPD:NDI-Se in the active layer, the shelf-life (∼1000 h) of the all-PSC under ambient conditions was found to be much better compared to those of PSCs based on the other two binary copolymers, Co-3MT and Co-TPD.</P>

Effects of cold pre-forging on microstructure and tensile properties of extruded AZ80 alloy

Kim, Ye Jin,Kim, Sang-Hoon,Lee, Jong Un,Choi, Jae Ok,Kim, Ha Sik,Kim, Young Min,Kim, Yongjin,Park, Sung Hyuk Elsevier Sequoia 2017 Materials science & engineering Structural materia Vol.708 No.-

<P><B>Abstract</B></P> <P>This study investigates the effects of cold pre-forging (CPF) on the extrusion load during hot extrusion and on the microstructure and mechanical properties of extruded AZ80 alloy. For this purpose, a billet is forged to 10% strain at room temperature and then subjected to indirect extrusion at 200°C. The CPF process causes the formation of a large amount of deformation twins and an increase in the dislocation density of the billet. The cold-forged AZ80 billet exhibits a higher extrusion load during extrusion than an unforged AZ80 billet, owing to the occurrence of twin-boundary hardening and enhanced strain-hardening effects in the former. The initial twins introduced by the CPF process promote dynamic recrystallization behavior during extrusion because they act as nucleation sites for recrystallization. As a result, the CPF process increases the area fraction of fine recrystallized grains and the microstructural homogeneity of the extruded alloy. The AZ80 alloy extruded after CPF shows a higher tensile strength and ductility than the AZ80 alloy extruded without CPF. The improvement in strength is attributed mainly to the decrease in the average grain size caused by an increased recrystallization fraction. The increased ductility is due to the reduced area fraction of coarse unrecrystallized grains, in which microcracks occur during tensile plastic deformation.</P>

Nuclear Magnetic Relaxation Study on the Interaction of Water with Hydrophilic Polymers

Kim,Sik Un,Sung,Yong Kiel,Kang,Shin Won 동국대학교 자연과학연구소 1981 자연과학연구 논문집 Vol.1 No.-

친수성 메타크리레이트 고분자와 물 사이의 상호작용을 펄스 NMR분광법에 의해서 연구하였다. 그 3차원적 친수성 메타크리에이트 고분자는 HEMA단량체와 EGDMA및 TEGDMA와 같은 가교제를 사용해서 제조하였다. 그 NMR연구에 의함년 적은 양의 물을 함융하고 있는 겔에 대한 스핀-라티스 이완시간(T₁)은 두 종류의 T₁와 T₁가 측정되어, 두 가지 종류의 결합수, 즉 강하게 결합된 물과 약하게 결합된 물이 존재하고 있음을 나타내 주었다. Poly(HEMA)수화겔 속에 있는 결합수의 스핀-라티스 이완시간은 얼음 속에 있는 물 자체의 프로톤의 스핀-라티스 이완시간(-16.40℃에서T₁=0.829sec)보다 훨씬 짧았다. 이 사실은 겔과 결합된 물 아시의 상호작용이 얼음 속에 있는 물 분자들 사이의 상호작용 보다도 강하다는 것을 보여준다. 수화겔 속의 물 프로톤에 대해서 측정한 T₁값은 순수한 액체 물(34℃에서 T₁=4.50sec)에 대한 값보다 훨씬 줄어들었다. 그리고 겔 속에 물의 양이 증가됨에 따라 펄스증폭강도는 단일지수함수의 성질을 보여주었다. 그 수화겔 속에 있는 물 프로튼에 대한 스핀-스핀 이완시간(T₂)의 측정값은 T₁측정값보다 약10배 낮았으며 적은 양의 물을 함유하고 있는 영역에서는 거이 일정하게 유지되었다. 결합수만을 함유하는 영역을 벗어나서 T₂의 측정값은 물의 함유량이 증가함에 따라 급격히 증가함을 나타내 주었다. 이 사실은 많은 양의 물을 함유하는 수화겔에서는 계면의 물이나 벌크상태의 물의 양이 더 많이 존재하게 되어 물 프로톤의 이동노가 증가하고 있다는 증거가 된다. The interaction of water with hydrophilic methacrylate polymers have been studied by using pulse NMR relaxation spectroscopy. The hydrophilic three dimensional methacrylate polymers were prepared from 2-hydroxyethyl methacrylate(HEMA) monomer and crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and tetraethylene glycol dimethacylate (TEGDMA). The NMR relaxation studies showed that the spin-lattice relaxation times (T₁) of low water sontent gels show a double environments resulting in two spin-lattice relaxation times (T₁andT₁). The data indicate that there are two different kinds of bound water, i.e., strongly bound water and weakly bound water. The spin-lattice relaxation time of bound water in poly(2-hydroxyethyl methacrylate) dydrogels is much less than that of water protons in ice (T₁=0.829 set at -16.40). This fact shows that the interactions between the bound water molecules and the gel networks are stronger than that between the water molecules in ice. The measuted values for the water protons in the hyrdogels are gresatly reduced compared to that of liquid water (T₁=4.50 sec at 34). As the water content in the gels is increased, the pulse amplitude intensities show a single exponential begavior. The measuted values of spin-spin relaxation times (T₂) of the water protons in the hydorgels are approximately ten times less than that of T₁and are almost constant in the region of bound water content. Beyond the bound water contenct region, the T₂values rapidly increse as the water content increases. This evidence indicates that more interfacial and bulk-like water exists, resulting in a mobility increse in high water content hydrogels.

Crystal Structures of Vacuum Dehydrated Fully Cd²+ -Exchanged Zeolite A and Its Ethylene Sorption Complex

Kim, Un Sik,Kim, Duk Soo,Koh, Kwang Nak,Kim, Yang 濟州大學校 基礎科學硏究所 1991 基礎科學硏究 Vol.4 No.1

The crystal structure of dehydrated fully ?? - exchanged zeolite A evacuated at ?? Torr and 450℃ (a=12.225(2) Å) and of its ethylene sorption complex (a=12.219(2) Å) have been determined by single crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(1)℃. The structures were refined to final error indices, R₁=0.063 and R₂=0.065 with 266 reflections and R₁=0.055 and R₂=0.062 with 260 reflections, respectively, for which I>3σ(I). In both structures, six ?? ions lie at two distinguished three-fold axes of unit cell. Dehydrated ?? sorbs 4 ethylene molecules per unit cell at 25℃(vapor pressure of ethylene is ca. 100 Torr). Each ?? ion forms a lateral π complex with an ethylene molecule. Four ?? ions exist in a nearly tetrahedral environment, 2.210(7) Å apart from three framework oxygen ions (considering ethylene molecule as a monodentate ligand) and 2.67(6) Å from each carbon atom of ethylene molecule.

Virus Incidence of Sweet Potato in Korea from 2011 to 2014

Kim, Jaedeok,Yang, Jung wook,Kwak, Hae-Ryun,Kim, Mi-Kyeong,Seo, Jang-Kyun,Chung, Mi-Nam,Lee, Hyeong-un,Lee, Kyeong-Bo,Nam, Sang Sik,Kim, Chang-Seok,Lee, Gwan-Seok,Kim, Jeong-Soo,Lee, Sukchan,Choi, Hon The Korean Society of Plant Pathology 2017 Plant Pathology Journal Vol.33 No.5

A nationwide survey was performed to investigate the current incidence of viral diseases in Korean sweet potatoes for germplasm and growing fields from 2011 to 2014. A total of 83.8% of the germplasm in Korea was infected with viruses in 2011. Commercial cultivars that were used to supply growing fields were infected at a rate of 62.1% in 2012. Among surveyed viruses, the incidence of five Potyvirus species that infect sweet potato decreased between 2012 and 2013, and then increased again in 2014. Representatively, the incidence of Sweet potato feathery mottle virus (SPFMV) was 87.0% in 2012, 20.7% in 2013 and then increased to 35.3% in 2014. Unlike RNA viruses, DNA viruses were shown to decrease continuously. The incidence of Sweet potato leaf curl virus (SPLCV) was 5.5% in 2003, 59.5% in 2011, and 47.4% in 2012. It then decreased continuously year by year to 33.2% in 2013, and then 25.6% in 2014. While the infection rate of each virus species showed a tendency to decline, the virus infection status was more variable in 2013 and 2014. Nevertheless, the high rate of single infections and mixed infection combinations were more variable than the survey results from 2012. As shown in the results from 2013, the most prevalent virus infection was a single infection at 27.6%, with the highest rate of infection belonging to sweet potato symptomless virus-1 (SPSMV-1) (12.9%). Compared to 2013, infection combinations were more varied in 2014, with a total of 122 kinds of mixed infection.