• 한국콘텐츠학회논문지
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• 제11권4호
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• pp.18-26
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• 2011

스마트폰이 보급화 되면서 기존의 핸드폰과 다르게 사용자는 스마트폰에 탑재한 위치정보 서비스를 통하여 현재의 위치를 기준으로 주변의 여러 정보를 손쉽게 접근할 수 있게 되었다. 본 논문에서는 여러 스마트 폰 이용자간의 위치 정보 서비스를 실시간으로 제공하는 클라이언트-서버 모형의 시스템인 WeWhere를 제안한다. 이 시스템에서 클라이언트 측의 스마트폰 사용자는 스마트폰에서 제공하는 위치 정보 서비스를 활용하여, 현재 위치를 서버로 보내고 다시 서버에서 현 사용자와 연결된 다른 사용자의 위치 정보를 가져와 자신의 스마트폰에 표시를 통해 스마트폰 사용자간의 현재 위치를 파악할 수 있다. 현재 전세계적으로 대략 20만명이 제안된 WeWhere를 서버의 과부하 없이 정상적으로 사용하고 있다.

• 인터넷정보학회논문지
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• 제19권5호
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• pp.97-105
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• 2018

In this paper, we present our recent effort on the development of a portable OCS system (SCH-mOCS), which provides minimal but essential functionalities of conventional OCS systems. SCH-mOCS is targeted for the environment where Internet connection is not available and fast processing of essential patient information is needed. The main usage could be found at the outdoor environment, such as voluntary medical services at challenged regions. The target of the first usage of the system is in the rural area of Cambodia where medical service and ICT infrastructure is poor. We have been conducting voluntary medical services for 15 years in Cambodia, where the services usually run for 3 days and include outpatient diagnosis/consultation, medication, and simple surgeries. This medical service started in 2002, where about 20 SoonChunHyang University Bucheon Hospital staffs (doctors, nurses, and pharmacists) participated. We realized that a system like SCH-mOCS is needed: we have to consult many patients in a short period, so that a prompt response and prescription to the patients are very important. However, the conventional OCS system is not suitable, because the service is usually conducted outdoor environment where Internet connected computers cannot be installed. Moreover, since the service needs only a subset of the conventional hospital information system and fast system response, application of a full OCS is not practical. The adequate system is a bare minimal OCS system, with very simple and quickly manageable patient admission, consultation, and prescription functionalities. In this paper, we describe hardware as well as the software aspect of a mini-OCS we have developed for the purpose. We named the system SCH-mOCS (SoonChunHyang mini-OCS). We also describe the usage scenario of SCH-mOCS in order to demonstrate that the system is general enough to apply for other similarly challenged regions.

• Management Science and Financial Engineering
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• 제15권2호
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• pp.69-100
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• 2009

In this paper, we consider a relatively new two-machine flow shop scheduling problem where the unit time WIP cost increases as a job passes through various stages in the production process, and the objective is to minimize the total WIP (work-in-process) cost. Specifically, we study three special cases of the problem. First, we consider the problem where processing times on machine 1 are identical. Second, the problem with identical processing times on machine 2 is examined. The recognition version of the both problems is unary NP-complete (or NP-complete in strong sense). For each problem, we suggest two simple and intuitive heuristics and find the worst case bound on relative error. Third, we consider the problem where the processing time of a job on each machine is proportional to a base processing time. For this problem, we show that a known heuristic finds an optimal schedule.

• Genomics & Informatics
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• 제10권4호
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• pp.220-225
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• 2012

Recent rapid advances in genetic research are ushering us into the genome sequence era, where an individual's genome information is utilized for clinical practice. The most spectacular results of the human genome study have been provided by genome-wide association studies (GWASs). This is a review of the history of GWASs as related to my work. Further efforts are necessary to make full use of its potential power to medicine.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.119-122
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• 2005

In this paper, we investigated the recognition range according to modulation index for the ISO(International Standards Organization) 14443 13.56MHz contactless Type B RFID(Radio Frequency IDentification) system. We measured recognition range with changing modulation index step by step from 5% to 24% where we used 4 samples of Type B transponder with different resonance frequencies between 13.838MHz and 17.200MHz. While gradually increasing a distance in vertical direction from the center of the reader antenna, we measured the distance where the transponder's PUPI(Pseudo Unique PICC(Proximity IC Card) Identifier) is recognized continuously during 10 seconds and the distance where the transponder's PUPI is recognized at least two times during 5 seconds. From the measurement results, we found that the best recognition ranges were achieved when the reader had modulation index between 11% and 14%.

• 응용통계연구
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• 제25권4호
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• pp.543-552
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• 2012

Parrondo paradox is a counter-intuitive phenomenon where two losing games can be combined to win or two winning games can be combined to lose. When we trade stocks with a history-dependent Parrondo game rule (where we buy and sell stocks based on recent investment outcomes) we found Parrondo paradox in stock trading. Using stock data of the KRX from 2008 to 2010, we analyzed the Parrondo paradoxical cases in the Korean stock market.

• Kyungpook Mathematical Journal
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• 제62권4호
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• pp.769-772
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• 2022

Given a prime number p and a natural number m not divisible by p, we propose the problem of finding the smallest number r₀ such that for r ≥ r₀, every group G of order p^rm has a non-trivial normal p-subgroup. We prove that we can explicitly calculate the number r₀ in the case where every group of order p^rm is solvable for all r, and we obtain the value of r₀ for a case where m is a product of two primes.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.537-543
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• 1999

While there are to estimating design discharge , we are in trouble with how to separate area, Because discharges will be different depending on the shape of area even though there are same size of area . This study is for a reasonable presentation of design discharge method where there are changing characteristcs of area with SCS and Clark theory by sung HEC-1 Model. While we were Estimating desgin discharge with separating area in a relation to Time of Concentration(Tc) with SCS , Clark method, we found that if there are no variation of Tc the value of a discharge is not changed where shapes of area are different though. And from the result of analysis with SCS and Clark method, we ascertained that discharge by the SCS method was more bigger than that of the Clark where Area is less than 100ha. On the other hand, Clark method is more bigger in the more 1000ha.

• Kyungpook Mathematical Journal
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• 제63권2호
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• pp.167-173
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• 2023

Let G be a finite group and let ν(G) be the probability that two randomly selected elements of G produce a nilpotent group. In this article we show that for every positive integer n > 0, there is a finite group G such that ${\nu}(G)={\frac{1}{n}}$. We also classify all groups G with ${\nu}(G)={\frac{1}{2}}$. Further, we prove that if G is a solvable nonnilpotent group of even order, then ${\nu}(G){\leq}{\frac{p+3}{4p}}$, where p is the smallest odd prime divisor of |G|, and that equality exists if and only if $\frac{G}{Z_{\infty}(G)}$ is isomorphic to the dihedral group of order 2p where Z_∞(G) is the hypercenter of G. Finally we find an upper bound for ν(G) in terms of |G| where G ranges over all groups of odd square-free order.

• 대한수학회보
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• 제33권3호
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• pp.477-480
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• 1996

Let $\pi : Z \longrightarrow Y$ be a fiber bundle where Y and Z are compact Riemannian manifolds without boundary. We are primarily interested in the case where $\pi$ is a Riemannian submersion with minimal fibers; this is the case, for example, where Z is the sphere bundle of some vector bundle over Y or where Z is a principal bundle over Y.