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COMPARISONS OF LOSS FORMULAS FOR A CIRCUIT GROUP WITH OVERFLOW TRAFFIC
박철근,한동환 한국전산응용수학회 2012 Journal of applied mathematics & informatics Vol.30 No.1
Traditionally, ERM (Equivalent Random Method) is used to determine number of circuits in an over°ow circuit group with rough traffic which has vmr(variance to mean ratio) greater than one. Recently,IPP(Interrupted Poisson Process) approximate method which represents the collective feature of the overflow has been introduced. The negative binomial loss formula can be applied to determine the required number of circuits in the overflow circuit group. In this paper, we deal with the negative binomial loss formula and determination method of number of circuits. We also analyze and compare these three loss formulas.
Approximate Analysis of an N-design Call Center with two types of agents
박철근,Dong Hwan Han,Kwang Hyun Baik 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.5
In this paper, we analyze an N-design call center with skill-based routing, in which one pool of agents handles two types of calls and another pool of agents handles only one type of calls. The approximate analysis is motivated by a computational complexity that has been ob- served in the direct stochastic approach and numerical method for finding performance measures. The workforce staffing policy is very important to the successful management of call centers. So the allocation scheduling of the agents can be considered as the optimization problemof the correspond-ing queueing system to the call center. We use a decomposition algorithm which divides the state space of the queueing system into the subspaces for the approximate analysis of the N-design call center with two different types of agents. We also represent some numerical examples and show the impact of the system parameters on the performance measures.
Pathologic Evaluation of Breast Cancer after Neoadjuvant Therapy
박철근,정우희,구자승 대한병리학회 2016 Journal of Pathology and Translational Medicine Vol.50 No.3
Breast cancer, one of the most common cancers in women, has various treatment modalities. Neoadjuvant therapy (NAT) has been used in many clinical trials because it is easy to evaluate the treatment response to therapeutic agents in a short time period; consequently, NAT is currently a standard treatment modality for large-sized and locally advanced breast cancers, and its use in early-stage breast cancer is becoming more common. Thus, chances to encounter breast tissue from patients treated with NAT is increasing. However, systems for handling and evaluating such specimens have not been established. Several evaluation systems emphasize a multidisciplinary approach to increase the accuracy of breast cancer assessment. Thus, detailed and systematic evaluation of clinical, radiologic, and pathologic findings is important. In this review, we compare the major problems of each evaluation system and discuss important points for handling and evaluating NAT-treated breast specimens.
Ferroportin and FBXL5 as Prognostic Markers in Advanced Stage Clear Cell Renal Cell Carcinoma
박철근,허자윤,함원식,최영득,신상준,조남훈 대한암학회 2021 Cancer Research and Treatment Vol.53 No.4
Purpose Advanced stage clear cell renal cell carcinoma (ccRCC) involves a poor prognosis. Several studies have reported that dysfunctions in iron metabolism–related proteins may cause tumor progression and metastasis of this carcinoma. In this study, we investigated the impact of the expression of iron metabolism–related proteins on patient prognoses in advanced stage ccRCCs. Materials and Methods All of 143 advanced stage ccRCC specimens were selected following validation with double blind reviews. Several clinicopathological parameters including nuclear grade, perirenal fat invasion, renal sinus fat invasion, vascular invasion, necrosis, and sarcomatoid/rhabdoid differentiation were compared with the expression of ferroportin (FPN), and F-Box and leucine rich repeat protein 5 (FBXL5), by immunohistochemistry. FPN and FBXL5 mRNA level of ccRCC from The Cancer Genome Atlas database were also analyzed for validation. Results FPN and FBXL5 immunohistochemistry showed membrane and cytoplasmic expression, respectively. Based on the H-score, cases were classified as low or high expression with a cutoff value of 20 for FPN and 15 for FBXL5, respectively. Low expression of FPN and FBXL5 were significantly associated with patient death (p=0.022 and p=0.005, respectively). In survival analyses, low expression of FPN and FBXL5 were significantly associated with shorter overall survival (p=0.003 and p=0.004, respectively). On multivariate analysis, low expression of FBXL5 (hazard ratio, 2.001; p=0.034) was significantly associated with shorter overall survival. Conclusion FPN and FBXL5 can be used as potential prognostic markers and therapeutic targets for advanced stage ccRCC.
QUEUEING ANALYSIS OF GATED POLLING SYSTEM FOR DYNAMIC BANDWIDTH ALLOCATION SCHEME IN AN EPON
박철근,Bara Kim,Dong Hwan Han 한국전산응용수학회 2004 Journal of applied mathematics & informatics Vol.16 No.-
In this paper, we investigate the mean queue length and themean packet delay of a dynamic bandwidth allocation(DBAscheme inan Ethernet passive optical network(EPONWe focus on the interleavedpolling system with a gated service discipline. We assume that input pack-ets arrive at an optical network unit(ONUaccording to Poisson process.We use a continuous time queueing model in order to nd the queue lengthdistribution of the gated interleaved polling system with the rst stageinput queue and the second stage transmission queue. We give some nu-merical results to investigate the mean queue lengths and mean packetdelays for the symmetric polling system with statistically identical stations.
박철근,정해,김진희 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.9
최근 인터넷을 기반으로 하는 응용프로그램과 인터넷 사용자들의 급격한 증가에 부응해 가입자 루프의 고속화 방안으로 여러 가지 PON 방식이 도입되고 있다. GPON은 이러한 PON 방식중 대표적인 접속망 기술로 상향 트래픽의 효율적인 전송을 위해 DBA 방안을 채택하고 있다. 본 논문에서는 GPON에서 동적대역 할당방안의 지연 성능을 분석하기 위해 2단계 버퍼를 갖는 개찰 폴링 시스템을 도입한다. 평균 사이클 타임을 유도하고 패킷의 평균 지연 시간을 구하기 위해 연속시간 큐잉 모델을 사용한다. 수치해석 결과를 이용하여 대칭형 폴링 시스템에 대한 지연 성능을 조사한다.