• YAKHAK HOEJI
• /
• v.34 no.5
• /
• pp.348-364
• /
• 1990

The activities of twenty-one flavonoids and their related compounds on the hypersensitivity reaction against various antigens were studied in vitro and in vivo. 1. Generally flavonoids inhibited significantly the homologous passive cutaneous anaphylaxis (PCA) induced by reaginic antibody as compared as anaphylaxis by compound 48/80-induced mast cell degranulation, and so more strongly active in the IgE-mediated anaphylaxis than non-IgE-mediated anaphylaxis. 2. Flavonids inhibited remarkably Arths reaction, hemolysin titer, delayed hypersensitivity, haemagglutinin titer, rosette forming cells and plague forming cells against sheep red blood cells, and so it exhibited that flavonoids inhibited type 2, 3 and 4 hypersensitivity. 3. Quercetin, kaempferol, hesperetin, disodium cromoglycate, malvin and baicalein were active dose-dependently in the all types of hypersensitivity. Fisetin, daidzein, morin, narigin, flavone, catechin, rutin, hesperidin, neophsperidin, apigenin and chrysin were significantly active in the various types of hypersensitivity, but apigenin, rutin and catechin were less active in the delayed hypersensitivity. Taxifolin was significantly active in PCA and histamine-induced anaphylaxis except other types of hypersensitivity. Rotenone and cyanin also inhibited all types of hypersensitivity, but they are toxic. 4. Based on these results from hypersensitivity, the following flavonoid structure-activity relationships became apparent. 1) Flavonoids with $C_{2-3}$ double bond in C-ring were more active than that of $C_{2-3}$ saturation. 2) Flavonoids with $C_4$ ketone group in C-ring were more active than abscence of them except catechin and malvin. 3) Flavonoids with benzene ring at positions 2 or 3 in C-ring exhibited same activities. 4) Flavonoids with opening of the C-ring does not abolish their activities. 5) The glycosylated flavonoids in position 3 or 7 was less active than their aglycone. 6) Flavonoids with the more hydroxy group in A and B-ring were more active. 7) Flavonoids with or without $C_3-OH$ did not change their activities.

• Journal of Institute of Convergence Technology
• /
• v.7 no.2
• /
• pp.13-16
• /
• 2017

The design of sealing mechanisms of a manual pressure valve was analyzed with FE analysis for a hydrogen fuels charge and discharge system of FCEV. The damage prediction of the O-ring with respect to the material models of rubbers was calculated by the gap analysis of the backup ring and O-ring according to the internal pressure. Two kinds of the rubber material characteristic models were adopted to the O-ring. One was the linear elastic and the other was hyperelastic of Ogden $3^{rd}$ order model. The experimental data of urethane of Shore hardness 90 was utilized to the curve fitting of hyperelastic properties. It was found that the contact pattern of the backup ring was different in two models and the sealing mechanism was better in the case of the hyperelastic characteristic model.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.10
• /
• pp.3343-3348
• /
• 2012

The possible ways for increasing the antioxidant properties of vitamin E have been investigated with density function theory. The effect of replacing three methyl groups of vitamin E with various substituents such as electron donating and electron withdrawing groups on the antioxidant properties of vitamin E were investigated. Also the effects of the reducing the number of atoms in the heterocyclic ring and replacing the oxygen heteroatom with other heteroatoms on the antioxidant properties of vitamin E were investigated. The novel structures that obtained from replacing methyl groups with substituents such as $NH_2$, OH, COOH and NHMe have greater antioxidant activity than vitamin E. Obtained results reveal that novel structure that obtained with replacing O with NH hetroatom would be a better antioxidant than vitamin E. The results reveal that reducing the number of atoms in the heterocyclic ring is a better way to synthesize novel antioxidants.

• BMB Reports
• /
• v.50 no.8
• /
• pp.393-400
• /
• 2017

Plants are constantly exposed to a variety of abiotic stresses, such as drought, heat, cold, flood, and salinity. To survive under such unfavorable conditions, plants have evolutionarily developed their own resistant-mechanisms. For several decades, many studies have clarified specific stress response pathways of plants through various molecular and genetic studies. In particular, it was recently discovered that ubiquitin proteasome system (UPS), a regulatory mechanism for protein turn over, is greatly involved in the stress responsive pathways. In the UPS, many E3 ligases play key roles in recognizing and tethering poly-ubiquitins on target proteins for subsequent degradation by the 26S proteasome. Here we discuss the roles of RING ligases that have been defined in related to abiotic stress responses in plants.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.1
• /
• pp.55-77
• /
• 2012

A Modern Rock TBM is a tunnel excavation method combining the conventional tunnelling method with the mechanized tunnelling method. It is a hybrid system that excavates a tunnel with TBM and supports the ground by ring beam, wire mesh, rock bolt, shotcrete, i.e., conventional tunnelling method. In the Modern Rock TBM, a ring beam is similar to a steel rib in NATM in the way that uses H-beam. But using a ring beam is more effective than a steel rib because it is installed in a closed-circle. Therefore, improving the performance of the ring beam is a key factor for achieving tunnel stability. In this respect, this study introduces a pressurized ring beam that might be functioning more effectively by confining convergence during tunnel excavation. In order to verify the effect of the pressurized ring beam, a three-dimensional numerical analysis was conducted. The numerical analysis confirms an increase in the minimum principal stress and reduction in the plastic strain that triggers excessive displacement. The analysis result also indicates a decrease in the relative displacement occurring after installing the ring beam, and expansion in spacing between the ring beams.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.31 no.4
• /
• pp.1-15
• /
• 2018

Objectives: Osteoporosis is considered a serious human disease. We developed an extract of mixed herbs containing root of Platycodon grandiflorum (ExMH-PGR), which is expected to be effective in preventing or treating osteoporosis. The aim of this study was to investigate the anti-osteoporotic effect of ExMH-PGR in osteoblastic MC3T3-E1 cells and osteoclastic RAW 264.7 cells. Methods: To examine the anti-osteoporotic effect of ExMH-PGR, osteoblast and osteoclast differentiation were induced and cultured with various concentrations of ExMH-PGR. Alkaline phosphatase (ALP) activity, collagen synthesis, osteocalcin production, and mineralization in MC3T3-E1 cells were analyzed. Tartrate-resistant acid phosphatase (TRAP) activity and the formation of actin ring in RAW 264.7 cells were analyzed. Results: ExMH-PGR at concentration up to $25{\mu}g/mL$ significantly increased ALP activity, collagen synthesis, osteocalcin production, and mineralization in MC3T3-E1 cells. ExMH-PGR at 50 to $200{\mu}g/mL$ significantly inhibited TRAP activity and the formation of actin ring in RAW 264.7 cells. Conclusions: These results demonstrate that ExMH-PGR stimulates osteoblastic activities and inhibits osteoclastic activities in in vitro systems, suggesting that ExMH-PGR might be considered as an anti-osteoporotic candidate for treatment of osteoporosis disease.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.1
• /
• pp.139-150
• /
• 1997

For high-speed networks, a new ring protocal is proposed in this paper. A ring network combined with destination removal can achieve much higher network throughput than the channel transmission rate. However, such a network exhibits fairness problems. Over a past few years, global fairness algorithms such as ATMR and Metaring have been proposed to solve such problems. But the ring access time delay and fairness in such networks are sensitive to the network parameters such as network size and traffic distribution. In addition to guaranteeing fair ring access to all nodes, there are several other important performance aspects in such networks. The one is that fairness is enforced while node throughputs are kept as high as possible. And another performance measure is access delay and more specifically Head-Of-Line(HOL) delay, i.e., the amount of time the first cell in the transmission buffer of a node has to wait before it accesses the ring. HOL delay is a mijor component in the transmission jitter of the synchronous traffic transmission. A key idea of the proposed ring protocol is to find the nodes that have much more chances to access the ring than any other nodes in the independently distributed node architecture. Since destined by many cells need to share a part of the bandwidths with the next node for the fairness in as much as performance degradation does not become critical. To investigate the performance behavior of the proposed ring protocol for various network condition,s several performance parameters wuch as ring access time delay, and throughput are compared with those of the ATMR and Metaring protocols using simulation package, SIMAN.

• Bulletin of the Korean Mathematical Society
• /
• v.47 no.5
• /
• pp.907-913
• /
• 2010

Let D be an integrally closed domain with quotient field K, * be a star operation on D, X, Y be indeterminates over D, $N_*\;=\;\{f\;{\in}\;D[X]|\;(c_D(f))^*\;=\;D\}$ and $R\;=\;D[X]_{N_*}$. Let b be the b-operation on R, and let $*_c$ be the star operation on D defined by $I^{*_c}\;=\;(ID[X]_{N_*})^b\;{\cap}\;K$. Finally, let Kr(R, b) (resp., Kr(D, $*_c$)) be the Kronecker function ring of R (resp., D) with respect to Y (resp., X, Y). In this paper, we show that Kr(R, b) $\subseteq$ Kr(D, $*_c$) and Kr(R, b) is a kfr with respect to K(Y) and X in the notion of [2]. We also prove that Kr(R, b) = Kr(D, $*_c$) if and only if D is a $P{\ast}MD$. As a corollary, we have that if D is not a $P{\ast}MD$, then Kr(R, b) is an example of a kfr with respect to K(Y) and X but not a Kronecker function ring with respect to K(Y) and X.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.3 no.6
• /
• pp.55-68
• /
• 1995

Approximately 30 to 70 % of the mechanical losses in a reciprocating engine are contributed by the friction at the piston ring-cylinder interface. The friction characteristics of the piston ring during engine operation is known to as mixed lubrication experimentally. The mixed lubrication models based on the Average Reynolds Equation have been used by this time in order to study the tribological performance of the ring. However, the Average Reynolds Equation contains the expected value term(${\bar{h}}_r$) of local film thickness as well as nominal film thickness(h), so that the work of numerically solving ${\bar{h}}_r$ must be included to obtain the pressure in the oil film. The process of solving ${\bar{h}}_T$ causes a greater multiplying in the numerical solution. In this paper the mixed lubrication analysis using the Simplified Average Reynolds Equation in the piston ring is presented. This equation has only h as oil film thickness term. Therefore the tedious numerical procedure required to obtain ${\bar{h}}_T$ is not needed, and also, computation time can be reduced.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.6
• /
• pp.834-838
• /
• 1996

The diagnosis of the plasma in the facing targets sputtering system was performed in mixture gas of Ar 0.18-0.0 Pa, Xe 0.0-0.18 Pa and $O_2$ 0.02 Pa by using Langmiur's probe and the effect of plasma-damage to surface smoothness and magnetic characteristics of Ba ferrite films was clarified. The electron density $N_e$ and the electron temperature $T_e$ were evaluated at the center of the plasma and at the neighborhood of the anode ring. $T_e$ decreased and $N_e$ increased with increase of $P_{Xe}$ at the center of plasma. For the measurement at the neighborhood of the anode ring, $T_e$ was almost constant and $N_e$ took the minimum value at $P_{Xe}$ of 0.1 Pa, where Ba ferrite films with excellent c-axis orientation and magnetic characteristics were obtained. It was suggested that the restriction of the bombardment of recoiled particles as well as the suppress of plasma-damage were effective for obtaining good surface smoothness and excellent magnetic characteristics and it was useful for decreasing the crystallization temperature of Ba ferrite films.