• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2004.11a
• /
• pp.380-380
• /
• 2004

• Bulletin of the Korean Chemical Society
• /
• v.12 no.4
• /
• pp.380-382
• /
• 1991

Pictet-Spengler reaction of the N-hydroxytryptophan ethyl ester (4) with N-protected thiazolidine aldehyde (8) has been carried out. The product, compound (9b), might be a possible precursor for the eudistomins C, E, K, and L.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.4
• /
• pp.380-384
• /
• 1996

Lithium trimethylalkynylaluminates, prepared conveniently by reacting trimethylaluminum with lithium alkynide, readily react with aldehydes and ketones to give the corresponding propargyl alcohols in 70-95% yields. The reaction is highly chemoselective; thus many other functional groups such as amides, nitriles, epoxides and halogen compounds are inert under the reaction conditions. The reagents also show an excellent 1,2-regiospecificity in the reactions with cyclic or acyclic α,β-unsaturated carbonyl compounds.

• Journal of Acupuncture & Meridian Studies
• /
• v.11 no.6
• /
• pp.380-380
• /
• 2018

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.9
• /
• pp.1633-1640
• /
• 2016

In this paper, we propose a open-ended rectangular microstirp patch antenna with fork-shaped feeding structure. This antenna extends the effective bandwidth by transforming single or multi resonant frequency and is designed planar monopole structure with microstrip line to satisfy the WLAN bands (2.4 - 2.484, 5.15 - 5.35, 5.25-5.825 GHz). The substrate is printed in 0.8 mm thickness on an FR-4 board. A commercial 3D simulation tool was used to analyze surface current and electromagnetic field distribution in order to analyze the operation mode and reconfiguration principle of antenna. According to the lengths of individual patches, simulated reflection loss was compared to obtain optimized values. When it was designed with the optimized values, it satisfied WLAN bands (2.380 - 2.710, 4.900 - 5.950 GHz), if the switch is off, and 2.4 WLAN band (2.380 - 2.710 GHz). From the fabricated and measured results, measured results of return loss, gain and radiation patterns characteristics displayed for operating bands.

• The Korean Journal of Zoology
• /
• v.18 no.3
• /
• pp.147-156
• /
• 1975

In order to determine the influence of low atmospheric pressure on serum glutamic oxaloacetic transaminase (SGOT) and serum lactic dehydrogenase (SLDH) activities of rats, blood samples were collected from laboratory-conditioned male rats of the Sprague-Dawley strain which were randomly grouped into control and the experimental subjected to a series of one hour-exposure a day to low atmospheric pressure of 500 and 380mmHg up to the the time of 15 day. Results obtained indicated that decompression caused marked alterations in SGOT and SLDH levels when compared to that of the control. The trend of increases or decreases in these enzyme levels were similar in both 500 and 380mmHg exposed rats although the changes were greater in the latter group. Thus, generally all the experimental rats showed temporary steady state to low atmospheric pressure. Changes in enzymatic contents depended on the intensity and extent of the environmental stress under study. The lower the atmospheric pressure the greater is the effect on these serum enzyme levels.

• Current Research on Agriculture and Life Sciences
• /
• v.3
• /
• pp.92-98
• /
• 1985

The experiments were conducted to investigate the activity changes of peroxidase, existence of isoenzyme and the changes of reserved substances in tomato under subatmospheric pressure storage condition. The results obtained were as follows: 1. Soluble fraction showed the highest peroxidase activity and followed by cell wall fraction, mitochondria fraction and ribosome fraction in that order. 2. Peroxidase activity was decreased during the ripening and senescence period in tomato. Especially, peroxidase activity in tomato was higher at a room temperature ($25^{\circ}C$) than at a low temperature ($15^{\circ}C$). The decreasing inclination was similar in both treatment. The peroxidase activity was higher in 380 Torr, than in 570 Torr. 3. At least, two isoperoxidases(Soluble or solubilized) were identified from different extraction procedures. Three of four isoenzymes were recognized from a vertical slab of polyacrylamide gel electrophoresis. 4. The changes of components in tomato under SAP were generally affected by temperature and pressure. Especially, quality of tomato stored at a low temperature ($15^{\circ}C$) and SAP (380 Torr.) was best during storage.

• Journal of the Korean Society for Heat Treatment
• /
• v.33 no.5
• /
• pp.232-238
• /
• 2020

Heating experiments using the 7075 aluminum alloy in the state of billet and extrudate have been performed to investigate the pertinent ranges of working temperatures and holding times for the application to the various automobile parts. The 7075 specimens from raw billet of 152 mm in diameter and 400 mm in length prior to extrusion were used for heating with a holding time of 10 minutes at temperatures between 380℃ and 550℃. Then, an extrusion process using the billet has been fulfilled at 380℃ with extrusion speed of 0.8 mm/min to get an plate-type extrudate of 75 mm in width and 4.2 mm in thickness. The samples from the extrudate were subjected to heating experiments at temperatures between 380℃ and 440℃ with holding times such as 10 min, 30 min, 60 min and 120 min at each heating temperature. The microstructures were investigated on the optical and EBSD micrographs. The hardness measurement and the tensile test have been performed to investigate the effect of the heat treatment on the mechanical property. The results showed for the 7075 extrusion process that the safe heating of billet can be performed below 450℃ and the extrusion can be done safely up to 400℃.

• Journal of Preventive Medicine and Public Health
• /
• v.54 no.5
• /
• pp.380-381
• /
• 2021

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.2
• /
• pp.380-388
• /
• 1994

Study on the chaotic stirring has been performed numerically and experimentally for a shallow rectangular tank accompanying a vortex shedding. The model is composed of a rectangular tank with a vertical plate with a length half the width of the tank. The tank is subject to a horizontal sinusoidal oscillation. The chaotic stirring was analysed by Poincare sections, unstable manifolds and Lyapunov exponents. As Reynolds number is increased the stirring effect is decreased due to the growth of a regular regions near the lower surface of the tank. In the other hand decrease of Reynolds number gives a weaker vortex shedding resulting in the poorer stirring effect. It was also found that the Lyapunov exponent is the highest at the dimensionless period of 1.3-1.5, which seems to be the best condition for the efficient stirring. The experimental visualization for the deformation of materials exhibits the striation pattern similar to the unstable manifold obtained numerically.