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Dive into the research topics where Ja Kyung Koo is active.

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Featured researches published by Ja Kyung Koo.


Bulletin of The Australian Mathematical Society | 1991

On holomorphic differentials of some algebraic function field of one variable over C

Ja Kyung Koo

We give holomorphic differentials of some algebraic function field K of complex dimension one which is a generalisation of a hyperelliptic field.


arXiv: Number Theory | 2016

Some applications of modular units

Ick Sun Eum; Ja Kyung Koo; Dong Hwa Shin

We show that a weakly holomorphic modular function can be written as a sum of modular units of higher level. We further find a necessary and sufficient condition for a Siegel modular function of degree


arXiv: Number Theory | 2016

On some Fricke families and application to the Lang–Schertz conjecture

Ho Yun Jung; Dong Hwa Shin; Ja Kyung Koo

g


Forum Mathematicum | 2014

On some arithmetic properties of Siegel functions (II)

Ho Yun Jung; Ja Kyung Koo; Dong Hwa Shin

to have neither zero nor pole on the domain when restricted to certain subset of the Siegel upper half-space


Journal of Nonlinear Mathematical Physics | 2007

p-adic interpolating function associated with Euler numbers

Taekyun Kim; Daeyeoul Kim; Ja Kyung Koo

\mathbb{H}_g


Publicationes Mathematicae Debrecen | 2014

On some applications of Eisenstein series

Ick Sun Eum; Ja Kyung Koo; Dong Hwa Shin

.


arXiv: Number Theory | 2011

Algebraic integers as special values of modular units

Ja Kyung Koo; Dong Hwa Shin; Dong Sung Yoon

We first investigate two kinds of Fricke families consisting of Fricke functions and Siegel functions, respectively. And, in terms of their special values we generate ray class fields of imaginary quadratic fields, which is related to the Lang-Schertz conjecture.


Journal of The Korean Mathematical Society | 2007

On the infinite products derived from theta series II

Daeyeoul Kim; Ja Kyung Koo

Abstract. Let K be an imaginary quadratic field of discriminant . We deal with problems of constructing normal bases between abelian extensions of K by making use of singular values of Siegel functions. First, we find normal bases of ring class fields of orders of bounded conductors depending on dK over K by using a criterion deduced from the Frobenius determinant relation. Next, denoting by the ray class field modulo N of K for an integer we consider the field extension for a prime and a positive integer m relatively prime to p and then find normal bases of all intermediate fields over by utilizing Kawamotos arguments. We further investigate certain Galois module structure of the field extension with , which would be an extension of Komatsus work.


arXiv: Number Theory | 2018

Siegel families with application to class fields

Ja Kyung Koo; Dong Hwa Shin; Dong Sung Yoon

Abstract In this paper, we investigate some relations between Bernoulli numbers and Frobenius-Euler numbers, and we study the values for p-adic l-function.


Journal of The Korean Mathematical Society | 2018

Generation of ring class fields by eta-quotients

Ja Kyung Koo; Dong Hwa Shin; Dong Sung Yoon

We derive the uniqueness of the theta functions associated with certain quadratic forms. Furthermore, we show some partially multiplicative relations between the representation numbers of such quadratic forms. To this end we apply Fricke involutions and Hecke operators to Eisenstein series.

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Dong Hwa Shin

Hankuk University of Foreign Studies

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Bumkyu Cho

Pohang University of Science and Technology

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Daeyeoul Kim

Chonbuk National University

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