• Steel and Composite Structures
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• 제43권1호
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• pp.91-106
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• 2022

This paper has focused on presenting a three dimensional theory of elasticity for free vibration of 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) cylindrical panels resting on two-parameter elastic foundations. The elastic foundation is considered as a Pasternak model with adding a Shear layer to the Winkler model. The porous graphene foams possessing 3D scaffold structures have been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the shell thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. Three complicated equations of motion for the panel under consideration are semi-analytically solved by using 2-D differential quadrature method. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary at the curved edges. It is explicated that 3D-GrF skeleton type and weight fraction can significantly affect the vibrational characteristics of GrF-PMC panel resting on two-parameter elastic foundations.

• Steel and Composite Structures
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• 제48권3호
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• pp.275-291
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• 2023

This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) core and FG wavy CNT-reinforced face sheets. The porous graphene foam possessing 3D scaffold structures has been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the plate thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. It is explicated that 3D-GrF skeleton type and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. The plate's normalized natural frequency decreased and the straight carbon nanotube (w=0) reached the highest frequency by increasing the values of the waviness index (w).

• 한국노년학
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• 제30권3호
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• pp.831-842
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• 2010

최근 한국사회의 고령화 및 노인장기요양 보험제도의 시작으로 노인 신체기능 및 장애에 대한 관심이 증가한 가운데, 이에 영향을 미치는 요인 중 하나로 근위축비만(Sarcopenic obesity) 즉, 근육양 감소와 지방량 증가가 동시에 나타나는 현상에 대한 관심이 증가하고 있다. 비만과 근 위축 각각이 노인의 신체기능에 미치는 영향에 대한 연구는 존재하나, 근위축 비만이 노인의 신체기능 및 체력에 미치는 영향에 관한 연구는 극히 제한적이다. 이에 본 연구는 경기도 Y시에 자립적으로 거주하는 60세 이상의 여성고령자 257명(평균연령 74.5세)의 신체조성을 측정한 후 Davison의 분류법을 이용하여 정상체지방군, 높은 체지방군, 근위축군, 근위축비만군의 4개 군으로 분류하고 7개의 노인신체기능측정(의자에서 앉았다 일어서기, 아령들기, 상완 유연성, 정적형성, 2분 제자리 걷기, 하지 유연성 및 8 feet 앉았다 일어서서 돌아오기(8ft TUG))검사항목과 측정장치를 이용한 4개의 기초체력항목(악력, 자세안정성, 무릎신근력 및 굴근력)에 미치는 영향을 조사하였다. SPSS 12.0을 이용하여 일원배치분산분석과 다중비교검정을 위한 LSD 사후검정을 실시하였으며 유의수준은 5%에서 검정하였다. 정상군의 의자에서 앉았다 일어서기, 아령들기, 상완유연성, 2분 제자리 걷기 결과는 근위축군(p<.05)과 근위축비만군(p<.05)보다 유의하게 높았다. 정적평형성은 정상군이 근위축비만군에 비하여 유의하게 높았으며(p<.01), 근위축군이 근위축비만군보다 유의하게 높았다(p<.01). 8ft TUG는 근위축비만군만이 정상군에 비하여 유의하게 낮은 결과를 보였다(p<.01). 악력(F=20.87,p<.001), 60도에서의 최대 신근력은 정상군이 근위축군(p<.01)과 근위축비만군(p<.01)보다 유의하게 높았으며 60도에서의 최대 굴극력역시 정상군이 근위축군(p<.01)과 근위축비만군(p<.01)보다 유의하게 높은 결과를 보였다. 본 연구의 결과는 노후의 자립적 삶을 영위하기 위한 기능유지의 위험인자로서 비만상태보다는 근위축비만군임을 입증하였으며, 노후 신체허약의 위험인자로 근위축비만에 대한 중재가 필요함을 보여주고 있다.

• 생약학회지
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• 제38권3호통권150호
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• pp.245-253
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• 2007

Artemisia princeps PAMPANINI has been used in traditional medicine of the treatment of inflammatory, liver dysfunction and order disorder in the far east countries including Korea. The present study was carried out to investigate the hepatoprotective effects of ethanol extract of Artemisia princeps (AP) and its fermented agents (AP-F) by lactic acid bacteria derived from human intestinal bacteria on liver injured rat induced by $CCl_4$ and d-galactosamine. Hepatoprotective activity was monitored by estimating serum ALT, AST, ALP, LDH, superoxide dismutase (SOD), glutathione redeuctase (GR) and glutathione peroxidase (Gpx) activities in the liver injured by hepatotoxin. Pretreating rats with AP or AP-F at the same dosage regimen significantly suppressed the acute elevation of serum transaminase, ALP, LDH and GR activities, and significantly increased the lowering of blood SOD and GR activites induced by hepatoxin. Based on these findings, it is presumed that AP and APF may have the hepatoprotective effect on $CCl_4$ and d-galactosamine-induced hepatotoxicity rat.

• Anatomy and Cell Biology
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• 제57권1호
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• pp.119-128
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• 2024

Glucocorticoids play a physiologic role in the adult male reproductive functions, modulating gonadal steroid synthesis and spermatogenesis, through the glucocorticoid receptor (GR). The expression of GR has been described in several key testicular cell types, including somatic cells and early germ cell populations. Nothing is known on GR in human spermatozoa. Herein, we explored the GR expression and its possible role in normal and testicular varicocele semen samples from volunteer donors. After semen parameter evaluation by macro- and microscopic analysis, samples were centrifuged; then spermatozoa and culture media were recovered for further investigations. By western blotting and immunofluorescence analyses we evidenced for the first time in spermatozoa the presence of GR-D3 isoform which was reduced in sperm from varicocele patients. By treating sperm with the synthetic glucocorticoid dexamethasone (DEXA), we found that survival, motility, capacitation, and acrosome reaction were increased in both healthy and varicocele samples. GR involvement in mediating DEXA effects, was confirmed by using the GR inhibitor mifepristone (M2F). Worthy, we also discovered that sperm secretes different cortisol amounts depending on its physio-pathological status, suggesting a defence mechanism to escape the immune system attach in the female genital tract thus maintaining the immune-privilege as in the testis. Collectively, our data suggests a role for glucocorticoids in determining semen quality and function, as well as in participating on sperm immune defensive mechanisms. The novelty of this study may be beneficial and needs to take into account in artificial insemination/drug discovery aimed to enhancing sperm quality.

• 한국독어학회지:독어학
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• 제6집
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• pp.221-240
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• 2002

In diesem Beitrag habe ich zu zeigen versucht, dass eine bestimmte, im Zusammenhang mit $Pr\"{a}positionen$ der in-Gruppe formulierte Kasusregel einen Geltungsbereich aufweist und weitgehend auch die exklusive A(Akkusativ)- bzw. D(Dativ)-Rektion von $Pr\"{a}positionen$ zu bestimmen. Ich glaube einsichtig gemacht zu haben, dass die A/D-Markierung im $pr\"{a}positionalen$ und im nicht-$pr\"{a}positionalen$ Bereich weitgehend nach einem einheitlichen Prinzip erfolgt. Aus meinem Beitrag ergibt sich dass A-Markierung in der Gegenwartssprache einem einheitlichen Prinzip unterliegt, der Bezeichnung der limitativen Funktion der von der markierten Phrase vertretenen $Gr\"{o}{\ss}e$. Ihrerseits $l\"{a}sst$ sich die D-Markierung nicht nach einem einheitlichen Prinzip deuten. Der Dativ kennzeichnet im $Pr\"{a}positionalbereich$ sowie in ditransitiven Konstruktionen die syntaktische Funktion als eine nicht limitative. Beim indirekten Objekt in nicht-ditransitiven Konstruktionenn ist die D- Markierung nicht mehr nach diesem Prinzip zu $begr\"{u}nden$. Sie erfolgt nur aufgrund thematischer Rollen. Die Kennzeichnung einer $Gr\"{o}{\ss}e$ als eine limitative bzw. nicht-limitative ist das Prinzip, das sich hinsichtlich A-bzw. D-Markierung in der Gegenwartssprache erkennen $l\"{a}sst$. Der A wurde ein syntaktisch motivierter Kasus, der D hingegen ein teilweise syntaktisch, teilweise thematisch motivierter Kasus genannt. Eine Kasusmarkierung gilt hier als syntaktisch bedingt, wenn sie eine Phrase betrifft, deren syntaktische Funktion ohne Zuhilfenahme thematischer RoIlen definiert werden kann. Nach diesem Prinzip wurde die A-Markierung eine syntaktisch bedingte genannt, weil die von ihr gekennzeichneten syntaktischen Funktionen nicht nach thematischen Rollen zu $begr\"{u}nden$ sind Dies gilt anderseits nur teilweise $f\"{u}r$ die D-Markierung, so dass sie als eine nur teilweise syntaktisch bedingte gelten muss.

• 한국독어학회지:독어학
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• 제10집
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• pp.1-24
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• 2004

Wir leben heute in der sosenannten Wissensgesellschaft. Diese Geseilschaft kann durch den Zugang zu immensen Wissens- und Informationsbestanden sowie durch einen fruher nicht denkbaren Grad an $Akualit\"{a}t$ dieser Informationen gekennzeichnet werden Deutsche Unternehmen haben bereits erkannt, dass das Wissen ihrer Mitarbeiter den Wert eines Unternehmens $ma{\ss}geblich$ bestimmt. Deshalb fordern sie von ihren Mitarbeitern, sich immer speziellere, immer neuere Wissensinhaite bzw. Informationen immer schneller anzueignen. Dies gilt auch $f\"{u}r$ Fremdsprachen, deren Kenntnis im Prozess der weit vorangeschrittenen Internationalisierung und Globalisierung als ein wesentliches Instrument vorausgesetzt wird. Der Hangel an fremdsprachlichen $F\"{a}higkeiten$ in Betrieben wirkt sick vol allem auf ihre Kompetenz im Umgang mil einer steigenden Anzahl von $Gesch\"{a}ftskontakten$ und ihre $ausl\"{a}ndischen$ $M\"{a}rkte$ aus. D. h. er bedeutet in einer durch zunehmenden Wettbewerb bestimmten Weit Marktverluste. Unternehmen sollen Herausforderungen $bew\"{a}ltigen$, die $gro{\ss}e$ interaktive und kommunikative $F\"{a}higkeit$ erfordern, $Ver\"{a}nderungen$ zu begreifen, sich ihnen zu stollen und sie zu $\"{u}berwinden$, um erfolgreich einen $gr\"{o}{\ss}eren$ Wirkungskreis auf den $Weltm\"{a}rkten$ zv erreichen. Deutsche Unternehmen erkennen inzwischen die besondere Bedeutung von $Fremdsprachenf\"{a}higkeiten$ ihrer Mitarbeiter $f\"{u}r$ Erfdlgssicherung und -ausbau. Diese Erkenntnisse ergeben sich auch aufgrund von Unternehmensbefragungen (z.B. vom Institut der deutschen Wirtschafi, $K\"{o}ln$). In fast allen Unternehmen ist Englisch die Fremdsprache Nummer Eins. Sie brauchen allerdings mehr als eine Fremdsprache. In der Regel werden zwei bis drei Fremdsprachen pro Betrieb $ben\"{o}tigt$. Wie $gro{\ss}$ der Fremdsprachenbedarf ist, $h\"{a}ngt$ von verschiedenen Faktoren ab: 1) Je $gr\"{o}{\ss}er$ ein Betrieb ist, desto wichtiger werden die fremdsprachlichen $F\"{a}higkeiten$ seiner Mitarbeiter. 2) In Firmen mit Auslandsverbindung und Unternehmen, die Teil eines $ausl\"{a}ndischen $Betriebes sind bzw $ausl\"{a}indische$ Niederlassungen haben, ist der Fremdsprachenbedarf von $gro{\ss}er$ Bedeutung. 3) Nach Branchen ist der Fremdsprachenbedarf differenziert. Fremdsprachenkenntnisse sind im exportorientierten produzierenden Gewerbe unverzichtbar. 4) In den verschiedenen Unternehmensbereichen werden Fremdsprachenkenntnisse differenziert $ben\"{o}tigt$. Funktionsbereiche wie Verkauf und Kundenbetreuung haben den $st\"{a}rksten$ Fremdsprachenbedarf, Kommunikation ist eine wesentliche Voraussetzung $f\"{u}r$ erfolgreiche Verhandlungen. Je $gr\"{o}{\ss}er$ die sprachliche $F\"{a}higkeiten$ und das Geschick der Mitarbeiter sind, umso besser laufen die $Gesch\"{a}ftsverhandlungen$. Damit wird klar, weshalb sich viele deutsche Unternehmen beim Fremdsprachenlernen, bzw. bei der Fort- und Weiterbildung von Fremdsprachenkenntnissen ihrer Mitarbeiter spendabel zeigen.

• BMB Reports
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• 제40권3호
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• pp.382-395
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• 2007

The herb, Cajanus indicus L, is well known for its hepatoprotective action. A 43 kD protein has been isolated, purified and partially sequenced from the leaves of this herb. A number of in vivo and in vitro studies carried out in our laboratory suggest that this protein might be a major component responsible for the hepatoprotective action of the herb. Our successive studies have been designed to evaluate the potential efficacy of this protein in protecting the hepatic as well as renal tissues from the sodium fluoride (NaF) induced oxidative stress. The experimental groups of mice were exposed to NaF at a dose of 600 ppm through drinking water for one week. This exposure significantly altered the activities of the antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and the cellular metabolites such as reduced glutathione (GSH), oxidized glutathione (GSSG), total thiols, lipid peroxidation end products in liver and kidney compared to the normal mice. Intraperitoneal administration of the protein at a dose of 2 mg/kg body weight for seven days followed by NaF treatment (600 ppm for next seven days) normalized the activities of the hepato-renal antioxidant enzymes, the level of cellular metabolites and lipid peroxidation end products. Post treatment with the protein for four days showed that it could help recovering the damages after NaF administration. Time-course study suggests that the protein could stimulate the recovery of both the organs faster than natural process. Effects of a known antioxidant, vitamin E, and a non-relevant protein, bovine serum albumin (BSA) have been included in the study to validate the experimental data. Combining all, result suggests that NaF could induce severe oxidative stress both in the liver and kidney tissues in mice and the protein possessed the ability to attenuate that hepato-renal toxic effect of NaF probably via its antioxidant activity.

• 한국해양공학회지
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• 제20권6호
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• pp.88-92
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• 2006

Large-scale model tests of welded topside joints were carried out to observe the fatigue behavior of API 2W Gr.50 steel produced by POSCO. The fatigue crack behaviors for various loading conditions were measured and investigated around the critical joint sections. The experimental results have been verified with numerical approaches and also compared with the AWS D1.1 and DnV RP-C203 design curves. The large-scale experiment models were fabricated, based on the actual operating east area fixed platform. The dimensions of the models were slightly modified to accommodate the test facilities and capacities. The fatigue test was carried out having ${\Delta}Q$ of T1=705.6kN, T2=749.7kN and T3=793.8kN. The three specimens were statically loaded 20 times, with various loadings of about 50kN intervalsbetween the maximum and minimum loads required in the fatigue tests. This loading removed the residual stress in the specimen before the fatigue tests. The topside joint crack was initiated from the brace heel, where the maximum tensile stress occurred. The API 2W Gr.50 steel satisfied the AWS D1.1 detail category C and DnV RP-C203 detail category F ${\Delta}S-N$ curve.

• 대한수학회지
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• 제51권1호
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• pp.87-98
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• 2014

Let R be a commutative ring with identity and M an R-module. In this paper, we associate a graph to M, say ${\Gamma}(M)$, such that when M = R, ${\Gamma}(M)$ is exactly the classic zero-divisor graph. Many well-known results by D. F. Anderson and P. S. Livingston, in [5], and by D. F. Anderson and S. B. Mulay, in [6], have been generalized for ${\Gamma}(M)$ in the present article. We show that ${\Gamma}(M)$ is connected with $diam({\Gamma}(M)){\leq}3$. We also show that for a reduced module M with $Z(M)^*{\neq}M{\backslash}\{0\}$, $gr({\Gamma}(M))={\infty}$ if and only if ${\Gamma}(M)$ is a star graph. Furthermore, we show that for a finitely generated semisimple R-module M such that its homogeneous components are simple, $x,y{\in}M{\backslash}\{0\}$ are adjacent if and only if $xR{\cap}yR=(0)$. Among other things, it is also observed that ${\Gamma}(M)={\emptyset}$ if and only if M is uniform, ann(M) is a radical ideal, and $Z(M)^*{\neq}M{\backslash}\{0\}$, if and only if ann(M) is prime and $Z(M)^*{\neq}M{\backslash}\{0\}$.