• YAKHAK HOEJI
• /
• v.28 no.2
• /
• pp.97-100
• /
• 1984

We have investigated the feasibility of using cyclic ambident nucleophiles in s-triazine ring transformation reaction and found that they can replace the $N_{1}-C_{2-N_{3}$ fragment of s-triazine directly in basic conditions, yielding the corresponding bicyclic products. In this paper, we described the reaction and mechanistic aspects of s-triazine to pyrimidopyrimidine transformation by 6-aminouracil derivatives. This type of ring transformation is supposed to be first attempt that deals with the successful s-triazine to bicyclic heterocycle transformation.

• YAKHAK HOEJI
• /
• v.37 no.2
• /
• pp.113-118
• /
• 1993

3-Phenyl-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepine, which has pharmaceutical activities, was reacted with phenyl isothiocyanate to give 3-phenyl-9-phenyl(thiocarbamoyl)-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepi nium-betaine. New biheterocyclic compounds were prepared by the ring transformation reaction of the above reactive betaine with $\alpha$-haloesters and $\alpha$-haloketones such as ethyl bromoacetate, methyl bromoacetate, chloroacetone, and 4'-methoxyphenacyl bromide, respectively. In each ring transformation reaction, two major products supposed to be geometrical isomers were obtained.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.3
• /
• pp.511-514
• /
• 2002

• YAKHAK HOEJI
• /
• v.29 no.2
• /
• pp.107-109
• /
• 1985

A novel synthesis of 7-membered 1,3,5-benzotriazepine (IV) from 1,3-Dimethyl-5-azauracil in one step by s-Triazine ring transformation is reported.

• Journal of Mechanical Science and Technology
• /
• v.15 no.11
• /
• pp.1599-1604
• /
• 2001

Axisymmetric compressible flow field induced by shock diffraction from a finite cone is investigated with experimental and computational methods. Double-exposure holographic interferograms show ima ges of the density field integrated along the light path. Using the sight-integrated density based on the Able transformation, the axisymmetric computational results are compared qualitatively with the experiment. In the present paper, we observed some distinguishing flow physics: the fault structure of vortex ring, the shock-vortex interaction, and the morphological transformation of shock waves.

• YAKHAK HOEJI
• /
• v.26 no.1
• /
• pp.25-27
• /
• 1982

We had reported that s-triazine can readily be converted into the corresponding 5-substituted pyrimide. In order to develop new synthetic method of 5-fluorouracil, we tried to replace eliminating fragment, 1, 3-dimethylurea, by fluoroacetamide, which was expected to undergo nucleophilic attack by proton extraction of both .alpha.-hydrogen and aminohydrogen by lithium diisopropylamide (LDA). We found that 5-fluorouracil could be transformed from s-triazine under strong base condition like LDA as well as other 5-substituted pyrimidines.

• Archives of Pharmacal Research
• /
• v.13 no.1
• /
• pp.97-100
• /
• 1990

A convenient route is reported for the synthesis of fused pyrrolo [2, 3-d][1, 3]-oxazine and pyrrolo [2, 3-d]-pyrimidine derivatives from 2-amino-1-benzyl-3-t-butoxy-carbonyl-4, 5-dimethylpyrrole.

• Journal of the Korean Mathematical Society
• /
• v.56 no.2
• /
• pp.539-558
• /
• 2019

An ideal of a commutative ring is called a d-ideal if it contains the annihilator of the annihilator of each of its elements. Denote by DId(A) the lattice of d-ideals of a ring A. We prove that, as in the case of f-rings, DId(A) is an algebraic frame. Call a ring homomorphism "compatible" if it maps equally annihilated elements in its domain to equally annihilated elements in the codomain. Denote by $SdRng_c$ the category whose objects are rings in which the sum of two d-ideals is a d-ideal, and whose morphisms are compatible ring homomorphisms. We show that $DId:\;SdRng_c{\rightarrow}CohFrm$ is a functor (CohFrm is the category of coherent frames with coherent maps), and we construct a natural transformation $RId{\rightarrow}DId$, in a most natural way, where RId is the functor that sends a ring to its frame of radical ideals. We prove that a ring A is a Baer ring if and only if it belongs to the category $SdRng_c$ and DId(A) is isomorphic to the frame of ideals of the Boolean algebra of idempotents of A. We end by showing that the category $SdRng_c$ has finite products.

• 한국해양학회지
• /
• v.8 no.2
• /
• pp.68-74
• /
• 1973

The present paper concerns the age determination and growth of butter fish, Pampus argenteus from the southwestern waters of Korea by otolith reading. 743 specimens taken by stow-net in the southern part of the Yellow Sea and northeastern part of the East China Sea during the period from October 1972 to September 1973 were examined. Results of the study are summarized as follows: 1. Sex ratio of females to males was found to be 2:1. 2. Ring marks on the otolith were found to be formed twice a year, once during the period of January-May and the other time in September. 3. The Lee's phenomenon was observed on the otolith sample. 4. The relationship between the radius of otolith(R) and fork length(L) was found to be as follows: R=0.3069+0.0133L 5. Calculated fork length at the time of otolith ring formation are found to be as follows:I-ring,71.67mm; II-ring, 125.05mm; III-ring, 168.65mm; IV-ring, 201.74mm; V-ring, 225.80mm; VI-ring, 240.84mm. 6. Maximum fork length calculated according to the diagram of Walford's growth transformation was found to be 281.5mm. 7. Growth curve, when related to the von Bertalanffy's equation, was laid out as $L_{t}=281.5[1-e$^{-0.674(t-0.128)}]$

• YAKHAK HOEJI
• /
• v.44 no.4
• /
• pp.325-333
• /
• 2000

The 1,3-dipolar cycloaddition reaction of the quinoxaline 4-oxides 2 with 2-chloroacrylonitrile gave the 2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxalines 3, which were converted into the 2,3,4,6-tetrahydro-1H-1,2-diazepino[3,4-b]quinoxalines 5-7. The reaction of compounds 3 with selenium dioxide in acetic acid/water resulted in ring transformation to give the 1,4-dihydro-4-oxopyridazino[3,4-b]quinoxalines 8.