서울의 PPNG 발생 빈도(1991-1992)

김재홍,윤기범,박평원,김영진,전경민,김영태,김중환,곽호,구상완,송민석,유옥,지혜구,김동원,문상은,박영립,정승호,성범진,성순제,엄주용,황정열,이기홍,이주협,전태진 대한화학요법학회 1994 대한화학요법학회지 Vol.12 No.1

The prevalence of PPNG among pretreated gonorrhea cases isolated at the STD clinic of Choong-Ku Public Health Center in Seoul has been studied and reported annually since 1981. In 1991, 123 strains of N.gonorrhoeae were isolated, among which 58(47.1%) were PPNG. In 1992, 98 starains of N.gonorrhoeae were isolated, among which 51(52.0%) were PPNG. In all, 109(49.3%) strains were found to be PPNG among 221 strains isolated between 1991-1992. The prevalence of PPNG in Seoul showed increased tendency till 1989, thereafter, it has been stationary or slightly decreasing.

양이장단자극을 이용한 각성유지 및 수면유도

정환목,배기성,김형식,우창진,최평,이만기 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

풍력 발전 시스템의 기동특성 분석

부평국,김일환 제주대학교 공과대학 첨단기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.2

This paper presents the analysis of starting characteristics in wind power generating system. In this field, induction machine is mainly used as a generator. If it is applied at this field, there will be appeared the large inrush currents compared with rated current when starting. So this is a big problem for stability of power system and generating control system. According to control methods for starting, we can get different results. To analyze the proposed method, computer simulation using Psim are presented to support the discussion.

액체-고체 순환유동층에서 액상의 반경 방향 혼합 및 액체-고체 Chaotic 흐름 거동

강석환,이찬기,송평섭,강용,김상돈,김승재 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.2

직경이 0.102m이고 높이가 3.5m인 액체-고체 순환유동층의 상승관에서 압력요동 및 액체의 반경 방향 혼합 특성을 고찰하였다. 상승관에서 얻은 압력요동을 해석하기 위하여 chaos 이론을 도입하였다. 액체 유속, 유동입자의 크기 그리고 고체 유동입자의 순환속도가 연속액상의 반경방향 분산계수 및 압력요동의 위상공간투영과 상관차원에 미치는 영향을 결정하였다. 본 연구의 결과 액상의 반경방향 분산계수는 유동입자의 크기와 순환속도가 증가함에 따라 증가하였으며 액상의 유속이 증가함에 따라 감소하였다. 상승관에서 압력요동의 위상공간투영은 유동입자의 크기가 고체 유동입자의 순환속도가 증가함에 따라 점점 분산되고 복잡하게 되었으나, 액체유속이 증가함에 따라서는 위상공간에서 궤적의 분산이 다소 감소하는 경향을 나타내었다. 압력요동의 상관차원은 유동입자의 크기와 고체 순환속도가 증가함에 따라 증가하였으나, 액체의 유속이 증가함에 따라서는 큰 변화가 없었다. 본 연구의 결과는, 상승관에서 액상의 반경 방향 혼합 특성 압력요동 측정함으로써 실시간으로 예측하는 것을 가능하게 하여 실제공정에 응용함으로써 그 실용적 측면이 크다고 하겠다. Characteristics of pressure fluctuations and liquid dispersion in the radial direction were investigated in the riser of a liquid-solid circulating fluidized bed whose diameter was 0.102m and 3.5m in height. The concept of chaos theory was employed to analyze the pressure fluctuations obtained in the riser. Effects of liquid velocity, particle size, and solid circulation rate on the liquid radial dispersion coefficient and phase space portraits and correlation dimension of pressure fluctuations were determined. It was found that the radial dispersion coefficient of liquid phase increased with increasing particle size or solid circulation rate, but decreased with increasing liquid velocity. The attractor in the phase space portraits became more scattered and complicated with increasing particle size or solid circulation rate, but it became somewhat less scattered with increasing liquid velocity. The correlation dimension of pressure fluctuations increased with increasing particle size or solid circulation rate, but it did not change considerably with increasing liquid velocity. The results of this study enable us to predict the characteristics of liquid radial dispersion by means of the pressure fluctuations for the practical applications.

액체-고체 순환유동층의 상승관에서 액상의 점도가 고체체류량 및 열전달계수에 미치는 영향

이찬기,강석환,신광식,송평섭,강용,김상돈 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.4

직경이 0.102 m이고 높이가 3.5 m인 액체-고체 순환유동층에서 액체의 점도가 고체입자의 체류량과 열전달계수에 미치는 영향을 검토하였다. 밀도가 2,500 kg/㎥인 유리구슬(d_(p)=1.0, 1.7, 2.1 또는 3.0 mm)과 CMC 용액(μ_(L)=0.96-38 mPas)을 각각 고체상과 액체상으로 사용하였다. 액체-고체 순환유동층에서 고체입자의 체류량은 액체의 유속이나 점도가 증가함에 따라 감소하였고 유동입자의 크기나 입자의 순환속도가 증가함에 따라 증가하였다. 액체-고체 순환유동층에서 열전달계수는 액체의 점도가 증가함에 따라 감소하였고 유동입자의 크기나 순환속도가 증가함에 따라 증가하였으나, 액체의 유속이 증가함에 따라서는 큰 변화가 없었다. 액체-고체 순환유동층에서 고체입자의 체류량과 열전달계수는 다음과 같이 실험변수와 무차원군에 의해 상관식으로 얻을 수 있었다. E_(S) = 0.783U^(-0.100)_(L)G^(0.164)_(S)d^(0.302)_(p)μ^(-0.036)_(L) h = 4349.3U^(0.010)_(L)G^(0.099)_(S)d^(0.151)_(p)μ^(-0.015)_(L) ◁그림삽입▷ Effects of liquid viscosity on the solid holdup and heat transfer coefficient have been investigated in the riser of a liquid-solid circulating fluidized beds, whose diameter is 0.102 m and 3.5 m in height. Glass beads (d_(p)=1.0, 1.7, 2.1 or 3.0 ㎜) whose density is 2,500 ㎏/㎥ and aqueous solutions of carboxymethy cellulose (CMC)(μ_(L)=0.96-38 mPas) have been used as the solid and liquid phase, respectively. It has been found that the solid holdup decreases with increasing liquid velocity or viscosity, but it increases with increasing solid particle size or solid circulation rate. The heat transfer coefficient decreases with increasing liquid viscosity but it increases with increasing particle size or solid circulation rate, however, it does not change considerablely with increasing liquid velocity. The solid holdup and heat transfer coefficient have been well correlated in terms of operating variables or dimensionless groups as fellow: ◁수식원문참조▷

초소성 알루미늄합금(Al-6%Cu-0.4%Zr, Al7475)의 미세조직 변화 및 초소성 인장시험

李相龍,李廷煥,申坪雨,金鉉澈,李榮琁 國立 昌原大學校 産業技術硏究所 1998 産技硏論文集 Vol.12 No.-

This study examined microstructures with SPF(superplastic forming) temperatues and strain amount in a superplastic aluminum alloys, Supral 100(Al-6%Cu-0.4%Zr) and Al 7475, The SPF temperature of Supral 100 was estimated as 450℃ using m value and flow stress by superplastic tensile test. The microstructures were evaluated with temperature changes just before superplastic deformation in static recrystallization experiments, and it was found that amount of recrystallization was small below 425℃ and grain coarsening occured above 475℃ as ZrAl₃precipitation lost in inhibiting ability grain coarsening. Therefore optimum SPF temperature proved 450℃. Beside The SPF temperature of Al 7475 was estimated as 515℃ using m value and flow stress by superplastic tensile test.

Reports : Stanniocalcin 2 enhances mesenchymal stem cell survival by suppressing oxidative stress

( Pyung Hwan Kim ),( Sang Su Na ),( Bomnaerin Lee ),( Joo Hyun Kim ),( Je Yoel Cho ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.12

To overcome the disadvantages of stem cell-based cell therapy like low cell survival at the disease site, we used stanniocalcin 2 (STC2), a family of secreted glycoprotein hormones that function to inhibit apoptosis and oxidative damage and to induce proliferation. STC2 gene was transfected into two kinds of stem cells to prolong cell survival and protect the cells from the damage by oxidative stress. The stem cells expressing STC2 exhibited increased cell viability and improved cell survival as well as elevated expression of the pluripotency and self-renewal markers (Oct4 and Nanog) under sub-lethal oxidative conditions. Up-regulation of CDK2 and CDK4 and down-regulation of cell cycle inhibitors p16 and p21 were observed after the delivery of STC2. Furthermore, STC2 transduction activated pAKT and pERK 1/2 signal pathways. Taken together, the STC2 can be used to enhance cell survival and maintain long-term stemness in therapeutic use of stem cells. [BMB Reports 2015; 48(12): 702-707]

Time-evolving genetic networks reveal a NAC troika that negatively regulates leaf senescence in <i>Arabidopsis</i>

Kim, Hyo Jung,Park, Ji-Hwan,Kim, Jingil,Kim, Jung Ju,Hong, Sunghyun,Kim, Jeongsik,Kim, Jin Hee,Woo, Hye Ryun,Hyeon, Changbong,Lim, Pyung Ok,Nam, Hong Gil,Hwang, Daehee National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.21

<▼1><P><B>Significance</B></P><P>Leaf senescence is regulated in a complex manner, involving time-dependent interactions with developmental and environmental signals. Genetic screens have identified key regulators of senescence, particularly late-stage senescence regulators. Recently, time-course gene-expression and network analyses, mostly analyses of static networks, have predicted many senescence regulators. However, senescence is defined by time-evolving networks, involving the temporal transition of interactions among senescence regulators. Here, we present time-evolving networks of NAM/ATAF/CUC (NAC) transcription factors, central regulators of leaf senescence in <I>Arabidopsis</I>, via time-course gene-expression analysis of NACs in their mutants. These time-evolving networks revealed a unique regulatory module of NACs that controls the timely induction of senescence-promoting processes at a presenescent stage of leaf aging.</P></▼1><▼2><P>Senescence is controlled by time-evolving networks that describe the temporal transition of interactions among senescence regulators. Here, we present time-evolving networks for NAM/ATAF/CUC (NAC) transcription factors in <I>Arabidopsis</I> during leaf aging. The most evident characteristic of these time-dependent networks was a shift from positive to negative regulation among NACs at a presenescent stage. ANAC017, ANAC082, and ANAC090, referred to as a “NAC troika,” govern the positive-to-negative regulatory shift. Knockout of the NAC troika accelerated senescence and the induction of other <I>NAC</I>s, whereas overexpression of the NAC troika had the opposite effects. Transcriptome and molecular analyses revealed shared suppression of senescence-promoting processes by the NAC troika, including salicylic acid (SA) and reactive oxygen species (ROS) responses, but with predominant regulation of SA and ROS responses by ANAC090 and ANAC017, respectively. Our time-evolving networks provide a unique regulatory module of presenescent repressors that direct the timely induction of senescence-promoting processes at the presenescent stage of leaf aging.</P></▼2>

성인에서의 담관 낭종과 췌담관 합류 이상

김명환,김영환,김효정,이성구,서동완,최호순,이승규,유병무,민영일,고문수,민병철,이미화,임미경,김표년 대한소화기내시경학회 1996 Clinical Endoscopy Vol.16 No.1

Background/Aims: Choledochal cyst is a congenital dilatation of extraor intrahepatic bile duct . Recently, anomalous union of pancreaticobiliary duct(AUPBD) is supposed to be one of the major causes of choledochal cyst. The aims of this study are to assess the association ratio of AUPBD in choledochal cyst and whether the AUPBD in choledochal cyst have a clinical significance. Methods: The study subjects were 35 adult patients who were diagnosed by ERCP in Asan Medical Center from August, 1990 to July, 1995. We have classified the type of choledochal cyst and AUPBD according to Todani and Kimura, respectively. Result: The number of choledochal cyst was 14 cases(40%) in type I, I case(3%) in type II, 6 cases(17%) in type Ⅲ, 11 cases(31%) in type IVA. Three cases were unclassified. Among the 35 cases, 22 cases(63%) of choledochal cyst were associated with AUPBD. AUPBD was only seen in type I, IVA and unclassified form of choledochal cyst. The number of patients with type 1 AUPBD was 10(45%) and type 2 was 12(55%) by Kimura's classification. 'Che mean age was younger in patients with choledochal cyst and AUPBD(36.2 16 years) than in choledochal cyst aione(49.3 19 years). Acute inflammation and malignancy of biliary tree 8z pancreas were more commonly seen in patients with choledochal cyst and AUPBD than choledochal cyst alone. Conclusion: In patients with choledochal cyst, the association of AUPBD was not uncommon and they had more grave clinical course. AUPBD may be a contributing factor to develop mali~ancy in patiehts with choledochal cyst.

Synergistic Effect of Cu/CeO₂ and Pt-BaO/CeO₂ Catalysts for a Low-Temperature Lean NO_<i>x</i> Trap

Kim, Beom-Sik,Kim, Pyung Soon,Bae, Junemin,Jeong, Hojin,Kim, Chang Hwan,Lee, Hyunjoo American Chemical Society 2019 Environmental science & technology Vol.53 No.5

<P>A lean NO<SUB><I>x</I></SUB> trap (LNT) catalyst has been widely used for removing NO<SUB><I>x</I></SUB> exhaust from lean-burn engines. However, the operation range of LNT has been limited because of the poor activity of LNT catalysts at low temperatures (≤300 °C), especially in urban driving conditions. To increase NO<SUB><I>x</I></SUB> removal efficiency during lean-rich cycle operation, a Cu/CeO<SUB>2</SUB> (CC) catalyst was added to a Pt-BaO/CeO<SUB>2</SUB> (PBC) catalyst. In comparison to PBC- or CC-only catalysts, the physical mixture of PBC and CC catalysts (PBC + CC) exhibited a significant synergy for both NO<SUB><I>x</I></SUB> storage and reduction efficiencies. In particular, low-temperature activity below 200 °C was greatly enhanced. A Pt-BaO-Cu/CeO<SUB>2</SUB> (PBCC) catalyst, which was synthesized by depositing Pt and Cu together on a ceria support, showed poorer NO<SUB><I>x</I></SUB> removal efficiency. The origin of the synergistic effect over PBC + CC was investigated. Under lean conditions, the CC showed much better activity for NO oxidation, allowing for faster NO<SUB><I>x</I></SUB> storage on PBC. Under rich conditions, H<SUB>2</SUB> was generated <I>in situ</I> on the CC by a water-gas shift reaction then accelerated the reduction of NO<SUB><I>x</I></SUB>, which had been stored on PBC, with a higher selectivity to N<SUB>2</SUB>. This simple modification in the catalyst can provide an important clue to enhance low-temperature activity of the commercial LNT system.</P> [FIG OMISSION]</BR>