• Archives of Pharmacal Research
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• v.9 no.2
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• pp.115-117
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• 1986

Some coumarins were sythesized for the screening of their cytotoxic activities against L1210 cell. Of the conmarins sythesized, 6, 7-dihydroxycoumarin (esculetin) and 7, 8-dihydroxycoumain (dephnetin) as coumarins with dioxygenated A-ring, and 6-acetoxy-5, 7-dimethoxycoumarin and5, 7-dimethoxy-6-hydroxycoumarin as trioxygenated ones, show considerable cytotoxic activities, ED 50 being 4. 3, 8. 8, 17.2 and 5.5 $\mu$g/ml in the same other as the substances. THe extent oxygenation of the A-ring and the positions of the oxygen functions eventually play an important role for the cytotoxic activity.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.945-952
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• 1997

The reactions of diazoindanes and diazoindanones with triphenylphosphine have been studied in acetonitrile. The diazoindanes and diazoindanones react with triphenylphosphazine. The reaction of 1,3-bis(diazo)indan-2-one with a tenfold excess of triphenylphosphine in dry acetonitrile gave the 1,3-bis(phosphazino)indan-2-one, however in acetonitrile containing below of 1% water, the 1,3-bis(hydrazono)indan-2-one was produced by hydrolysis. The phosphazine compound could be easily converted into bishydrazone by recrystallization, due to small amounts of water in the solvent. The reactivity of triphenylphosphine toward diazoindanes and diazoindanones depends on the structrue of the diazo compounds.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.74-81
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• 1995

Several non-manifold data structures have been compared, which are radial-edge data structure, partial-face data structure, vertex-based data structure, and Yamaguchi's data structrue. All the entities in the data structures are classified into common entities and special entities. The entities are also classified as model entities, primitive entities bounding entities, and coupling entities. The four data structures for nonmanifold solid modelers are compared in terms of accessing efficiency, storage requirements, and inclusion of circulation. The results of comparison will serve as the basis to develope a nonmanifold modeler.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.108-113
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• 1993

The material for the machine tool structure should have high static stiffiness and damping in its property to improve both the static and dynamic performances. The static stiffness of a machine tool can be inceased by using either higher modulus material in the structure of a machine tool. However, the machine tool structrue with high stiffness but low damping is vulnerable to vibration at the resonance frequencies of the structure . For the high precision and highsped machine tool structure, therefore, the high damping capacity is most important in order to suppress vibration. The damping of a machine tool can not be increased by increasing the static stiffness. The best way to increase the damping capacity of the machine tool structure is to use a composite material which is composed of on material with high stiffness with low damping and another material with low stiffness with high damping. Therefore, in this paper, the bed of the ultra high precision grinding machine for mirror surface machining of brittle materials such as ceramics and composite materials was designed and manufactured with the epoxy concrete material. The epoxy concrete material was prepared by mixing epoxy resin with different size sands and gravels. The modulus, compressive strength, coefficient of thermal expansion, specific heat, and damping factor were measured by varying the compaction ratio, sizes and contents of the ingredients to assess the effect of the processing parameters on the mechanical properties of the material. Based of the measured properties, the prototype epoxy resin concrete bed for the mirror surface CNC grinding machine was designed and manufactured.

• Korean Journal of Cognitive Science
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• v.1 no.2
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• pp.361-376
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• 1989

Norepoine is N-methylated by the enzyme phenly ethanolamine N-metyltransferase(PNMT)to form epinephrine.this enzyme is larhly restructed to the adrenal medulla where epinephrine in mammalian brain where epinephrine function as a neurotransmitter.It seems clear that central epinephrine is involved in the regulation of cardiovacular function and in several forms of hypertension.However,information about the struture of mammalian epinephrine forming enzyme has been limited until now.But recently we isolate bovine and human PNMT cDNA clone using gtll expression library and sequcde total nucleotide composition.To obtain information about the structrue of the human and rat PNMT proteins and gones and to further define the extent of the evolutionary relationships among the PNMT molecules of these species human and rat genomic DNA clones to PNMT were sequentially isolated and characterized.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.246-251
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• 1995

To reduce the size of structural members high strength concrete has recently been utilized for structrue such as ultra-high-rise buildings and prestressed concrete bridges in North America. and its compressive strength has gone up to 1300kgf/$\textrm{cm}^2$. In Japan, research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project, and this project purposed to develop the design compressive sstength of 1200kgf/$\textrm{cm}^2$. Considering these circumstance. the aim of this aim of this experimental study is to develop ultra-high-strength concrete with compressive stength over 2300kgf/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence on manufacturing of ultrahigh-strength concrete. The experimental factors selected in this study are mixing methods, curing methods, water-binder ratio, maximum size of coarse aggregate, and the replacement proportion of cement by silica fume. The results of this expermental study show that it is possible to develop the ultra-high-strength concrete with compressive strength over 2300kgf/$\textrm{cm}^2$.

• Korean Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.93-102
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• 1997

Most design changes are due to interferences and fit-up as parts are assembled if such a large product as an automobile or an aircraft is developed by many concurrent engineers. In this part (1) of the thesis, the assembly-centric modeling methodology with CAD systems is proposed in order to reduce the design changes. Unlike part-centric modeling method, a part is modeled with its own coordinate system which is used in downstream process as machining and measuring. The part coordinates initially have the same orientation as its assembly which is predefined in BOM (Bill of Material). Then, the corrdinates origin of the part is moved to its location to be assembled from that of its assembly coordinate system. To implement this methodology, the position data of the part w.r.t. its assembly are stored in a database to build the same hierarchical assembling structure as BOM structure. This modeling approach has the advantage of reflecting asembling sequence, because the process of positioning parts is similar to that of real assembling. And with the method, a designer can easily adjust all of the part positions of an assembly to resolve interferences if he modifies just the coordinates origin of the assembly, which results in moving included parts and assemblies together.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.111-118
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• 1997

The structrue of hydroxy-bisbenzoyloxy-allyloxycalix[4]arene (C45H36O6) has been determined by X-ray crystallography. The crystals are monoclinic, space group P21, unit cell constants a=11.045(3), b=33.545(2) c=10.319(4)Å, β=113.86(2)˚, Z=4, V=3496.0(1.8) Å3, DC=1.28 gcm-3. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated Mo-Kα radiation. The structure was solved by direct method and refined by full-matrix least-squares calculations to a final R value of 0.076 for 2945 observed reflections. Two independent enantiomeric molecules are crystallized in a 1:1 racemate mixture. They have the flattened cone conformation with the flattening hydroxy1 pheny1 rings. There is an intramolecular hydrogen bond in both molecules.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.54-62
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• 1994

This paper presents active control methodologies to suppress structural deflections of a composite beam using a distributed piezoelectric-film actuator and sensor. Three types of different controllers are employed to achieve vibration suppression. The controllers are established depending upon the information on the velocity components of the structrue and on the deflection magnitudes as well. They are constant-amplitude controller(CAC), constant-gain mcontroller(CGC), and constant-amplitude-gain controller(CAGC). For the minimization of the residual vibration (chattering in a settled phase), which is the practical shortcoming of the conventional CAC dur to time delay phenomenon of the hardware system, a new control algoritym CAGCis designed by selecting switching constants in an optimal manner with respect to the initial tip deflection and the applied voltage. The experimental investigations of the transient and forced vibration control for the first vibrational mode are undertaken in order to compare the suppression efficiency of each control algorithm. Moreover, simultaneous controllability of various vibrational modes through the proposed scheme is also experimentally verified by pressenting both the transfer function and the phase.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.59.3-60
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• 2020

We present the results of polarization observations at submillimeter wavelengths towards Monoceros R2 (Mon R2). The polarized thermal dust emission was obtained from SCUBA-2/POL-2 at 450 ㎛ and 850 ㎛, simultaneously. This observation is a part of the JCMT BISTRO survey project. The polarization angle distributions at 450 ㎛ and 850 ㎛ are similar and the mean value of angle differences at two wavelengths is 5.5 degrees. The Mon R2 is one of massive star-forming regions containing a clear hub-filamentary structure. The hub region shows star formation activities, and surrounding filaments provide channels for matters to move into the hub region. It is not well known the role of magnetic fields in a hub-filamentary structure. Some studies have shown well-ordered polarization segments along a filamentary structure and magnetic field morphology traced by polarization segments is interpreted as to help gas flow along the filamentary structrue. Our observations shows that filaments in Mon R2 have spiral structure and the magnetic field lines are parallel to the filaments. We interpret that the spiral structure can be formed by a rotation hub-filament system with gas flowing along the filaments to the hub. We found several dust clumps at the central part of the hub region of the Mon R2. They seems to be formed at locations where spiral field lines meet each other. These results show one observational example that a magnetic field play a role in gas flow.