아라미드 표면처리에 의한 실리콘/불소 고무와의 접착성 연구

이재호,이재동,박성민,이종우,Lee, Jae-Ho,Lee, Jae-dong,Park, Sung-min,Lee, Jong-woo 한국섬유공학회 2018 한국섬유공학회지 Vol.55 No.5

The interfacial adhesion property between aramid and rubber is a very important factor when aramid is applied as a reinforcing material for automotive heat-resistant hoses. This study examined the improvement of interfacial adhesion between aramid and rubber by applying plasma and a coupling agent to m-aramid. The SEM, AFM, and XPS characteristics were examined based on the plasma treatment conditions. The plasmatreated aramid was then treated with the coupling agent to analyze the interfacial adhesion with silicon, fluorine, and hybrid rubber. The plasma treatment resulted in an increase in the surface roughness of the aramid, and the mechanical properties of the aramid fabric decreased because the surface of the aramid was fibrillated. Moreover, the interfacial adhesion between aramid and rubber increased by 16.2% with the use of the coupling agent and plasma treatment.

Flash EEPROM에서 부유게이트의 도핑 농도가 소거 특성에 미치는 영향

이재호,신봉조,박근형,이재봉,Lee, Jae-Ho,Shin, Bong-Jo,Park, Keun-Hyung,Lee, Jae-Bong 대한전자공학회 1999 電子工學會論文誌, D Vol.d36 No.11

Flash EEPROM에서 칩 전체나 또는 칩의 한 블록에 속에 있는 모든 셀들의 소거는 Fowler-Nordheim (FN) 터널링 방식을 사용하여 일괄적으로 수행되고 있다. 이러한 FN 터널링에 의한 소거는 self-limited 공정이 아니기 때문에 일부의 셀들이 심하게 과소거되는 문제가 자주 발생하고 있다. 본 논문에서는 이러한 과소거 문제를 해결하기 위한 부유게이트의 최적 도핑 농도에 관하여 연구하였다. 이러한 연구를 위하여 다양한 도핑 농도를 갖는 n-type MOSFET과 MOS 커패시터를 제작하였고, 이 소자들의 전기적인 특성들을 측정 및 분석하였다. 실험 결과, 부유게이트의 도핑 농도가 충분히 낮다면 ($1.3{\times}10^{18}/cm^3$ 이하) 과소거가 방지될 수 있음을 볼 수 있었다. 이는, 소거시 부유게이트에 저장되었던 전자들의 대부분이 빠져나가면 부유게이트에 공핍층이 형성되어 부유게이트와 소스 사이의 전압 차가 감소하고 따라서 소거가 자동적으로 멈추기 때문이라고 판단된다. 반면에 부유게이트의 도핑 농도가 너무 낮을 경우 ($1.3{\times}10^{17}/cm^3$ 이하)에는 문턱 전압과 gm의 균일도가 크게 나빠졌는데, 이는 부유게이트에서 segregation으로 인한 불순물의 불균일한 손실에 의한 것이로 판단된다. 결론적으로 Flash EEPROM에서 과소거 현상을 방지하고 균일한 문턱 전압과 gm을 갖기 위한 최적의 부유게이트의 도핑 농도는 $1.3{\times}10^{17}/cm^3$에서 $1.3{\times}10^{18}/cm^3$의 범위인 것으로 발견되었다. All the cells on the whole memory array or a block of the memory array in the Flash EEPROM's are erased at the same time using Fowler-Nordheim (FN) tunneling. some of the cels are often overerased since the tunneling is not a self-limited process. In this paper, the optimum doping concentration of the floating gate solve the overerase problem has been studied. For these studies, N-type MOSFETs and MOS capacitors with various doping concentrations of the gate polysilicon have been fabricated and their electrical characteristics have been measured and analyzed. As the results of the experiment, it has been found that the overerase problem can be prevented if the doping concentration of the floating gate is low enough (i.e. below $1.3{\times}10^{18}/cm^3$). It is because the potential difference between the floating gate and the source is lowered due to the formation of the depletion layer in the floating gate and thus the erasing operation stops by itself after most of the electrons stored in the floating gate are extracted. On the other hand, the uniformity of the Vt and the gm has been significantly poor if the coping concentration of the floating, gate is too much lowered (i.e. below $1.3{\times}10^{17}/cm^3$), which is believed to be due to nonuniform loss of the dopants from the nonuniform segregation in the floating gate. Consequently, the optimum doping concentration of the floating gate to suppress the overerase problem and get the uniform Vt and has been found to range from $1.3{\times}10^{17}/cm^3$ to $1.3{\times}10^{18}/cm^3$ in the Flash EEPROM.

분산염색에서 Cotelomer 타입 계면 활성제의 응용

이재호,최해욱,정영진,황대연,최영호,이언필,Lee, Jae-Ho,Choi, Hae-Wook,Jung, Young-Jin,Hwang, Dae-Youn,Choi, Young-Ho,Lee, Eon-Pil 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.1

Multi-chain surfactants usually form micelles more easily than single-chain surfactants due to their low surface tension and low solubility in water. In this study we prepared cotelomers of multi-alkylated nonionic surfactants with a molecular structure $xR_nMA$-yVA (x; hydrophobic group, y; hydrophilic group, MA; methacrylic ester, VA; vinyl alcohol, R; alkyl group) and investigated their properties as surfactants for the disperse dyeing of cellulose acetate, nylon 6, and PET fibers. Some cotelomers were synthesized via a radical polymerization of vinyl monomers MA and VA using azobisisobutyronitrile (AIBN) as an initiator. The ratio of x/y and degree of polymerization of $xR_nMA$-yVA with an alkyl chain length (n) of 4 or 6 were controlled by adjusting the ratio of thiol to monomers. We found that a cotelomer with a degree of polymerization 9.9 showed better dispersing performances than cotelomer with a degree of polymerization 4.4 or 12.5, and that the degree of dispersion increased to a certain level and then decreased as concentration of cotelomer increased. The highest value of dye uptake for the three fibers was obtained when using a cotelomer with a monomer unit ratio (x/y) of 0.2 and 0.5 g/l of concentration was 0.5 g/l.

WiBro 환경에서 Overlay 기반의 Mobile IPv6 이동성 구현 및 성능 시험에 관한 연구

이재호,류형근,이재준,강선무,이재용,Lee, Jae-Ho,Ryu, Hyung-Keun,Lee, Jae-Jun,Kang, Sun-Moo,Lee, Jai-Yong 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.6b

A Mobile IP is considered for the efficient mobility function in IEEE 802.16/WiBro environment. However, during the deployment of WiBro, only some of the ACRs(Access Control Router) can support the Mobile IP function. Therefore, a WiBro network can not support the mobility function for the mobile node. In this paper, we implement an overlay-based Mobile IP function and measure the performance through a field trial. Moreover, we evaluate the possibility of commercial deployment and suggest areas that need to be improved. IEEE 802.16/WiBro 환경에서 효율적인 이동성을 위하여 Mobile IP 적용이 고려되고 있다. 하지만 WiBro 확산과정에서 Mobile IP 이동성을 지원하는 ACR과 지원하지 못하는 ACR이 혼재된 상황이 존재하고 있으며, 이럴 경우 단말의 이동성은 보장받기 어렵게 된다. 본 논문에서는 이러한 WiBro 환경에서 지속적인 단말 이동성을 지원하기 위하여 Overlay 기반의 Mobile IP 이동성을 실제로 구현하고 이에 대한 성능 시험을 시행한 후 현장 적용 가능성을 검증하고 향후 개선 필요 사항을 도출하였다.

T-형 $Ca^{2+}$ 채널 길항제인 Mibefradil을 첨가한 인간 정자의 첨체반응 관찰

이재호,손원영,이정하,이인선,김영찬,한징택,Lee, Jae-Ho,Son, Weon-Young,Lee, Jung-Ha,Lee, In-Sun,Kim, Young-Chan,Han, Ching-Tack 대한생식의학회 2000 Clinical and Experimental Reproductive Medicine Vol.27 No.1

Objective: The sperm acrosome reaction is a $Ca^{2+}$-dependent exocytotic event that is triggered by adhesion to the mammalian egg's zona pellucida. Previous studies suggested a role of $Ca^{2+}$ channels in acrosome reactions. This study was conducted to investigate the T-type calcium channel is operated in acrosome reaction of human spermatozoa. Method: Human semen samples were obtained from healthy donors with normal criteria. The spermatozoa were divided into five groups: Group 1 were non-treated as a control; Group 2 where spermatozoa were exposed to 5 ${\mu}M$ $Ca^{2+}$ A23187 $(Ca^{2+}i)$; Group 3 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and mibefradil; Group 4 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and nifedipine, and Group 5 where spermatozoa were treated with 5 ${\mu}M$ $Ca^{2+}i$ and both of mibefradil and nifedipine. Spermatozoa in all groups were retrieved after incubation for 15 and 30 minutes at $37^{\circ}C$. After staining with PSA-FITC, fluorescence was observed under a fluorescence microscope, and AR was evaluated on a total>100 spermatozoa/side. Result and Conclusion: We observed on acrosome reaction inhibition rate in human spermatozoa the various of concentration of mibefradil, nifedipine. Maximum response was noted with 1.0 ${\mu}M$ mibefradil and the decrease of acrosome reaction inhibition rate 45%. Nifedipine in acrosome reaction inhibition rate was only about 25%. The $Ca^{2+}i$-induced AR of spermatozoa was significantly suppressed by mibefradil. Incidence of the suppression was depending on concentration of mibefradil. Results from the present study suggest that the human spermatozoa possess T-type channel. The observation that reversible inhibitor of T channels in male germ cells provides a new mechanism of contraceptive action.

카자흐스탄 동카자흐스탄주 아이-카라울 동 광화대의 특성

이재호,김인준,김복철,Lee, Jae-Ho,Kim, In-Joon,Kim, Bok-Chul 대한자원환경지질학회 2008 자원환경지질 Vol.41 No.4

국내 안테나 기술 동향

이재호,Lee, Jae-Ho 한국정보통신집흥협회 2005 정보화사회 Vol.177 No.-

51.84Mbps VDSL QAM 수신기를 위한 통과대역 디지털 심볼 클록 복원방식

이재호,김재원,정항근,정진균,Lee, Jae-Ho,Kim, Jae-Won,Jeong, Hang-Geun,Jeong, Jin-Gyun 대한전자공학회 2000 電子工學會論文誌-SC (System and control) Vol.37 No.2

본 논문에서는 51.84Mbps의 전송 속도를 갖고, 16-QAM 변조방식을 사용하는 VDSL(고속 디지털 가입자 루프) 시스템에서, 전송 신호 주파수 스펙트럼의 밴드-에지 성분을 최대화함으로써 심볼 클록(12.96㎒)을 복원하는 방식에 대해 논의한다〔1〕. 디지털 방식의 PLL에서 여러 가지 특성들이 조사되었으며, NCO(Numerically Controlled Oscillator)에서 사용하는 룩-업 테이블의 효율적인 설계 방식을 제시하였다. In this paper, we discuss a symbol clock extraction scheme based on maximizing the band-edge component of the transmitted signal frequency spectrum for applications to 51.84Mbps VDSL system which uses a 16-QAM. The major characteristics of the digital PLL are examined. In addition, we suggest an efficient design method of a sinusoidal look-up table which is used for NCO.

건설사업 웹 기반 VE 정보시스템의 개념 모델

이재호,박찬식,Lee Jae-ho,Park Chan-Sik 한국건설관리학회 2005 건설관리 : 한국건설관리학회 학회지 Vol.6 No.3

가치공학(Value Engineering, 이하 VE)은 단기간 VE 워크샵을 통하여 분야별 전문가들이 팀을 구성하여 VE 업무 프로세스에 따라 다양한 과업을 수행한다. 그러나 최근까지 VE 워크샵 수행과정에서 활용되는 정보는 다양한 정보의 축적 및 활용방법이 체계적이지 못하기 때문에 VE 팀원들에게 유용하지 못한 실정이다 특히 VE 팀원간 정보의 신뢰성과 신속성, 원할한 의사소통의 장애요인이 되며, VE 워크샵 시간과 비용의 증가를 초래하는 원인이 되고 있다. 따라서 본 연구에서는 이러한 문제들을 해결하기 위하여 효율적 인 VE 정보활용 방법으로써 웹 기술을 이용한 YE 정보시스템의 개념 모델을 제안한다. Value Engineering(VE) Workshop executes many tasks with VE team members from various experts of construction field on the basis of VE Job Plan for a short period of time. However, the VE team members are not useful with using VE information until now because it is not systematic in the accumulation and application of VE information. Especially, these problems constitute the obstacles to communication, reliability and quickness of VE information. It also causes an increase of time and cost at VE Workshop. Therefore, the results of this study suggests the conceptual model of Web-Based Information System for VE(WISE) in order to improve the effectiveness of VE Workshop and solve the problem as is stated above.

키토산/PVA 블렌드 필름의 구조 및 특성

이재호,노창환,최해욱,정영진,황대연,이언필,Lee, Jae-Ho,Noh, Chang-Hwan,Choi, Hae-Wook,Jung, Young-Jin,Hwang, Dae-Youn,Lee, Eon-Pil 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.2

Chitosan/poly(vinyl alcohol)(PVA) blend films with non-toxicity, biodegradability, and biocompatibility were prepared by solvent blending method. The weight composition ratios of chitosan/PVA blend films were 100/0 (chitosan homopolymer), 75/25, 50/50, 25/75, and 0/100 (PVA homopolymer). Physicochemical properties of the prepared blend films according to various blend ratios were investigated by using universal testing machine, thermogravimeter (TGA), differential scanning calorimeter (DSC), wide angle X-ray diffractometer (WAXD), Fourier transform infrared (FTIR) spectrometer, and scanning electron microscope (SEM). The tensile stress and tensile strain of chitosan/PVA blend films increased as the amount of PVA increased. The thermal stability increased with increasing chitosan content in the chitosan/PVA blend films. The DSC curve of the PVA film shows an endotherm peak around $230^{\circ}C$, and the peak became smaller and broader with increasing chitosan content. The diffraction intensities of chitosan observed at 2 theta of $10^{\circ}$ decreased with increasing the content of PVA in the blend films, but the crystal intensities of the blend films increased as the amount of PVA increased. In the infrared spectra, the absorption band for -OH and -NH stretching vibrations in chitosan broadened and shifted obviously to lower wavenumber with the increase of PVA. Water-retention values of the chitosan/PVA blend films increased as the amount of PVA is increased owing to the hydrophilic nature of PVA. From the structural analyses, it is believed that chitosan and PVA are miscible due to the strong intermolecular hydrogen bonding.