• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.169-172
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• 2006

Most studies using state-space models have been conducted under the assumption of independently distributed noises in measurement and state equation without adequate verification of the assumption. To avoid the improper use of state-space model, testing the assumption prior to the parameter estimation of state-space model is very important. The purpose of this paper is to investigate the general relationship between parameters of state-space models and those of ARIMA processes. Under the assumption, we derive restricted parameter spaces of ARIMA(p,0,p-1) models with mutually different AR roots where $p\;{\le}\;5$. In addition, the results of ARIMA(p,0,p-1) case can be expanded to more general ARIMA models, such as ARIMA(p-1,0,p-1), ARIMA(p-1,1,p-1), ARIMA(p,0,p-2) and ARIMA(p-1,1,p-2).

• 수산경영론집
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• 제33권2호
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• pp.75-98
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• 2002

As a contribution to developing fishery stock assessment, optimum sustainable yield and its international standards such as MSY, MEY, and dynamic MEY for six recommended fisheries are developed using bio-economic models. For selecting the appropriate model, five models - Schaefer, Schnute, Walters and Hilborn, Fox, and CY&P models are tested in effort and catch data of six species. Surprisingly all the models except the CY&P model failed to satisfy statistical standards such as goodness-of-fitness and reliability. Generally, the CY&P model holds good fitness and statistically significant level for all of six fisheries. However, the CY&P model for squid, where the intrinsic growth rate is high, could not explain MSY, MEY, and dynamic MEY appropriately. This study makes a contribution to develop the modified model for the intrinsic growth rate of 1. The reformulated model represents the results reasonably even though the estimated equation has not good fitness. Although most of the CY&P models appear to have good fits and validated results for some cases, these models also seem to be quite sensitive to parameters which means a more stable model should be developed and data should carefully be handled. In particular biological and technical interactions such as multispecies, predator prey relationship, age structure and mortality should be taken into account. In addition, economic factors and fishing efforts such as price, cost, technical change and a reasonable function of fishing input should simultaneously be considered.

• 한국조경학회지
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• 제39권6호
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• pp.110-117
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• 2011

본 연구는 2010년 4월 3일부터 3가지 토양 조성에 따른 섬기린초의 월동 후 생육상태를 측정하였고, 초고-생장시간 생장모형을 개발하고자 하였다. 이를 위해 함수식(Logistic식과 Gompertz식)을 사용하였고, SPSS를 이용하여 비선형 회귀분석을 진행하였다. 섬기린초의 초고-생장시간 생장모형을 통하여 섬기린초 월동 후의 생장과정과 관리방법을 명확하게 파악할 수 있다. 섬기린초의 생육상태 측정치에 의하면, 펄라이트($P_1$)보다는 혼합한 토양($P_2P_1V_1$, $P_1P_2V_1$)의 생육상태가 더 양호하고, 평균초고는 최대 약 2배 정도의 차이가 나타났다. 그리고 섬기린초의 Logistic생장모형과 Gompertz생장모형의 평균결정계수($R^2$)는 0.995, 0.978 순으로 나타났으며, Logistic생장모형의 적합성은 Gompertz생장모형보다 높은 것으로 확인되었다. 또한 섬기린초의 생장모형을 통하여 월동 후의 생장 기간은 3기간으로 나눌 수 있으며, 생장형태는 "비교적 빠른 생장기간---아주 빠른 생장기간---느린 생장기간"으로 구분할 수 있다. 옥상녹화용 섬기린초를 관리할 때 빠른 생장기간에서만 관리하면 섬기린초의 생육상태는 많이 좋아질 것으로 판단된다.

• Journal of the Korean Statistical Society
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• 제21권1호
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• pp.47-58
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• 1992

The autocorrelation function structures of bilinear time series model BL(p, q, r, s), $r \geq s$ are obtained and shown to be analogous to those of ARMA(p, l), l=max(q, s). Simulation studies are performed to investigate the adequacy of Akaike information criteria for identification between ARMA(p, l) and BL(p, q, r, s) models and for determination of orders of BL(p, q, r, s) models. It is suggested that the model of having minimum Akaike information criteria is selected for a suitable model.

• Journal of Communications and Networks
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• 제15권2호
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• pp.228-239
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• 2013

Peer-to-peer (P2P) systems have proved the most effective and popular file sharing applications in recent years. Previous studies mainly focused on equal service and differentiated service strategies when peers have no initial data before their downloads. For an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when the initial data distribution of peers satisfies some special conditions. Moreover, we show how to minimize the time required to distribute the file to any number of peers. The proposed fluid-based models can reveal the intrinsic relations among the initial data amount, the peer set size, and the minimum last finish time. The closed-form expressions derived from the extended models can closely approximate chunk-based models and systems, especially for relatively large files. As an application of the extended models, we show how to provide differentiated service efficiently to multiple peer sets. Since no limits are imposed on the upload bandwidth of peers or the size of each peer set, we believe that our analytic process and the results achieved can provide not only fundamental insights into bandwidth allocation and data scheduling but also a helpful reference for both improving system performance and building an effective incentive mechanism for P2P file sharing systems.

• 대한치과기공학회지
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• 제41권4호
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• pp.287-293
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• 2019

Purpose: To evaluate the accuracy of the 3D printed die models and to investigate its clinical applicability. Methods: Stone die models were fabricated from conventional impressions(stone die model; SDM, n=7). 3D virtual models obtained from the digital impressions were manufactured as a 3D printed die models using a 3D printer(3D printed die models;3DM, n=7). Reference model, stone die models and 3D printed die models were scanned with a reference scanner. All dies model dataset were superimposed with the reference model file by the "Best fit alignment" method using 3D analysis software. Statistical analysis was performed using the independent t-test and 2-way ANOVA (α=.05). Results: The RMS value of the 3D printed die model was significantly larger than the RMS value of the stone die model (P<.001). As a result of 2-way ANOVA, significant differences were found between the model group (P<.001) and the part (P<.001), and their interaction effects (P<.001). Conclusion: The 3D printed die model showed lower accuracy than the stone die model. Therefore, it is necessary to further improve the performance of 3D printer in order to apply the 3D printed model in prosthodontics.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.535-539
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• 2009

Evapotranspiration (ET) is one of the main factor to understand the hydrologic cycle on land surfaces of entire globe. It accounts for about 65% of precipitation returning to the atmosphere. Accurate estimation of the ET is essential to many applications of water resources management, hydrology, meteorology, climatology, and agriculture. Over the past few decades, there have been extensive efforts to develop and validate a number of ET models. Priestley-Taylor (P-T) and Food and Agriculture Organization Penman-Monteith (P-M) models are generally recognized as simple, but great operational approaches to estimate ET over different land cover types. In this study, we compare/validate different models of increasing complexity, P-T, P-M, and Common Land Model (CLM) in croplands, IA.

• Reproductive and Developmental Biology
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• 제34권1호
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• pp.7-13
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• 2010

The binding affinity constants ($p(Od)_{50}$) and molecular docking scores (OS) between porcine odorant binding proteins pOBP (1HQP) and pPBP (1GM6) as receptor and a series of tetrahydrofuran-2-yl (A & B) analogues as substrate, and their interactions were discussed quantitatively using three-dimensional quantitative structure-activity relationship (30-QSAR) models. The statistical qualities of the optimized CoMF A models for pOBP were better than those of the CoMSIA models. The binding affinity constants and OS between substrate and receptor molecules were dependent upon steric and hydrophobic interaction. The DS constants of the substrates into the binding site of OBP (1HQP) were bigger than those of PBP (1GM6). The resulting contour maps produced by the optimized CoMFA model were used to identify the structural features relevant to the binding affinity in binding site of pOBP.

• 정보처리학회논문지D
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• 제11D권4호
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• pp.975-982
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• 2004

현재 많이 사용되고 있는 P2P 개념으로는 순수 P2P와 변형 P2P 구조가 있다. 순수 P2P의 모델에는 Gnutella와 Ktella등의 형태가 존재하고 변형 P2P로는 무수히 많은 형태가 존재한다. 순수 P2P 모델의 경우에는 정보 공유에서 연결성을 장점으로 Gnutella의 형태를 응용한 형태로 많이 사용되고 있지만 정보를 검색하거나 제공하기 위해 많은 트래픽을 소모하게 된다. 이와는 달리 변형 P2P 모델들 중 정보 공유 모델들이 존재하는데 이 모델들은 사용자에게 효율적이고 빠른 검색과 색인을 제공하기 위해 기존의 서버/클라이언트 형태를 취하고 있지만 확장성에 있어서 제공하는 서버의 능력에 의존할 수 밖에 없다. 파일공유 모델의 Peer들에 대해 연결성 유지를 위한 많은 부하와 사용자에 있어서 그룹에 대한 형태의 문제점 그리고 서버의 Fail로 인한 비 연결성에 대한 문제점을 해결하기 위해 본 논문에서는 라우팅 프로토콜 기법에서의 접근과 계층적 구조를 적용하고 Backup 시스템을 포함해서 대규모 네트워크에서 효율적인 그룹관리와 동적인 서버의 지정으로 신뢰성을 유지하기 위한 시스템을 설계 구현하여 그 우수성을 검증하였다.

• 자원환경지질
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• 제41권6호
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• pp.719-729
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• 2008

본 연구에서는 지구화학 모델을 활용하여 지하수 환경에서의 우라늄의 존재 형태, 흡착 및 이동 특성을 모사해 보았다. 흡착에 의한 우라늄의 지연 이동을 효과적으로 모사하기 위하여 3차원 지하수 유동 모델과 반응성 용질 이동 모델을 활용하였다. 모사 결과, $pCO_2=10^{-3.6}$조건에서 대부분의 우라늄 흡착(최대 99.5%)은 pH 5.5와 띠에서 발생하였다. $pCO_2$가 $10^{-2.5}$인 경우 우라늄이 대부분 흡착되는 pH범위는 6에서 7사이로 매우 좁았으며, 반면 $pCO_2=10^{-4.5}$인 경우에는 흡착되는 pH가 범위가 상대적으로 넓어 pH 5.5에서 8.5사이에서 대부분 흡착되었다. 음이온 화합물을 고려한 경우에는 pH 6 이하에서는 불소착물의 형성에 의해 우라늄 흡착이 감소하였다. 본 연구를 통하여, 우라늄 이동이 pH, $pCO_2$ 및 음이온의 종류와 농도 등 지하수의 지화학적 조건에 의해 상당히 영향을 받음을 알 수 있었다. 향후 여러 부지 조사 및 평가와 관련하여 우라늄 및 기타 유해성 화합물의 환경 영향을 예측하는데 있어 지구화학 모델이 중요한 도구로 활용되어야 할 것이다.