• International Journal of Control, Automation, and Systems
• /
• 제4권3호
• /
• pp.382-393
• /
• 2006

Mechanical system dynamics plays an important role in the area of computational structural biology. Elastic network models (ENMs) for macromolecules (e.g., polymers, proteins, and nucleic acids such as DNA and RNA) have been developed to understand the relationship between their structure and biological function. For example. a protein, which is basically a folded polypeptide chain, can be simply modeled as a mass-spring system from the mechanical viewpoint. Since the conformational flexibility of a protein is dominantly subject to its chemical bond interactions (e.g., covalent bonds, salt bridges, and hydrogen bonds), these constraints can be modeled as linear spring connections between spatially proximal representatives in a variety of coarse-grained ENMs. Coarse-graining approaches enable one to simulate harmonic and anharmonic motions of large macromolecules in a PC, while all-atom based molecular dynamics (MD) simulation has been conventionally performed with an aid of supercomputer. A harmonic analysis of a macroscopic mechanical system, called normal mode analysis, has been adopted to analyze thermal fluctuations of a microscopic biological system around its equilibrium state. Furthermore, a structure-based system optimization, called elastic network interpolation, has been developed to predict nonlinear transition (or folding) pathways between two different functional states of a same macromolecule. The good agreement of simulation and experiment allows the employment of coarse-grained ENMs as a versatile tool for the study of macromolecular dynamics.

• 대한안전경영과학회지
• /
• 제22권1호
• /
• pp.23-32
• /
• 2020

There has been a significant decline in the number of rail accidents in Korea since system safety management activities were introduced. Nonetheless, analyzing and preventing human error-related accidents is still an important issue in railway industry. As a railway system is increasingly automated and intelligent, the mechanism and process of an accident occurrence are more and more complicated. It is now essential to consider a variety of factors and their intricate interactions in the analysis of rail accidents. However, it has proved that traditional accident models and methods based on a linear cause-effect relationship are inadequate to analyze and to assess accidents in complex systems such as railway systems. In order to supplement the limitations of traditional safety methods, recently some systemic safety models and methods have been developed. Of those, FRAM(Functional Resonance Analysis Method) has been recognized as one of the most useful methods for analyzing accidents in complex systems. It reflects the concepts of performance adjustment and performance variability in a system, which are fundamental to understanding the processes of an accident in complex systems. This study aims to apply FRAM to the analysis of a rail accident involving human errors, which occurred recently in South Korea. Through the application of FRAM, we found that it can be a useful alternative to traditional methods in the analysis and assessment of accidents in complex systems. In addition, it was also found that FRAM can help analysts understand the interactions between functional elements of a system in a systematic manner.

• 응용통계연구
• /
• 제24권6호
• /
• pp.1197-1211
• /
• 2011

The actual power performance of historical structural change tests are compared under various alternatives. The tests of interest are F, CUSUM, MOSUM, Moving Estimates and empirical distribution function tests with both recursive and ordinary least-squares residuals. Our comparison of the structural tests involves limiting distributions under the hypothesis, the ability to detect the alternative hypotheses under one or double structural change, and smooth change in parameters. Even though no version is uniformly superior to the other, the knowledge about the properties of those tests and connections between these tests can be used in practical structural change tests and in further research on other change tests.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.179-187
• /
• 2022

The project performances can be measured in terms of meeting the project schedule, budget, and conformance to functional and technical specifications. Numerous studies have been conducted to examine the causes and effects of change orders for both vertical and horizontal construction, respectively. However, these studies mainly focus on a single project type, so this paper examines the impact of change order for cost growth and schedule overruns using four different building types to close the gap in the change order research area. A total of 211 building projects are collected from four building types: healthcare, residential, office, and education. Statistical analyses using ANOVA tests and linear regression models are used to examine the created metric $CO/day on the cost and schedule impacts. The results found that mean $CO/day values were not statistically different among building types, and that the sum of change orders is a statistically significant predictor of $CO/day. The results will help project stakeholders mitigate the negative change orders effects can be a challenge for project managers and researchers alike.

• 전자공학회논문지CI
• /
• 제39권6호
• /
• pp.11-23
• /
• 2002

한국어 형태론에 대한 기존의 전산모형은 선형적인 것들로 단어 내부구조 분석보다 형태소 분리 문제에만 관심을 두고 있다. 이러한 선형적 전산모형을 구문 분석 과정과 통합적으로 고려할 경우, 구문 단위 요소의 형성을 위해 형태소 분석 결과를 묶어야만 하는 추가적인 과정이 필요할 뿐만 아니라 의미적 직관성을 얻기도 어려웠다. 본 논문에서는 형태소 분리와 구문 요소 형성뿐만 아니라 단어의 구조 분석까지도 통합적으로 다룰 수 있는 단어통사론적 시각에 따른 전산 모형을 제안한다. 먼저 형태소 분리와 변형 문제를 다루기 위해 2단계형태론의 형식화를 도입하고, 품사 문맥을 반영하기 위해 기능성 구분문자를 제안한다. 그리고 형태소의 통사적 결합 검사를 위해 GLR에 기반한 변형 알고리즘을 제안한다.

• 원예과학기술지
• /
• 제32권2호
• /
• pp.165-170
• /
• 2014

본 연구는 완전제어형 식물공장에서 선형 지수 함수를 이용하여 재식거리($15{\times}10$, $15{\times}15$, $15{\times}20$, $15{\times}25$cm)에 따른 씀바귀의 생육과 수량 모델을 개발하고자 수행되었다. 개체당 건물중은 25cm 처리구가 가장 높았으며, 10cm 처리구가 가장 낮았다. 단위면적당 건물중으로 보면 15cm 처리구가 가장 높았으며, 25cm 처리구가 가장 낮았다. 따라서 씀바귀 생육을 위한 적정 재식밀도와 재식거리는 각각 44 plants/$m^2$와 $15{\times}15$cm였다. 정식 후 일수에 따른 건물중의 변화 곡선은 선형 지수적인 형태를 보였으며, 재식거리에 따른 선형 지수 형태를 이용하여 모델식을 예측할 수 있었다. 개체당 건물중과 개체당 생체중과의 관계는 재식거리와는 무관하게 직선적인 관계를 보여, 건물중 예측으로 생체중도 예측할 수 있었다. 선형 지수 함수식에서 작물생장율과 상대생장율, lost time는 쌍곡선 형태를 보였다. 씀바귀의 광사용효율는 $4.3-6.1g{\cdot}MJ^{-1}$였다. 재식거리에 따른 씀바귀의 생육과 수량은 선형 지수 함수식으로 정확하게 예측할 수 있었다. 결론적으로, 선형 지수 함수는 완전제어형 식물 공장에서 씀바귀의 생육과 수량을 예측하는데 유용한 함수였으며, 생육과 수량 모델을 개발할 수 있었다.

• 대한핵의학회지
• /
• 제39권4호
• /
• pp.257-262
• /
• 2005

목적 : 위배출신티그래피는 일반적으로 15분 간격으로 2시간 동안 촬영된다. 본 연구는 수학적 함수를 이용하여 90분까지 얻은 위잔류율 측정치를 가지고 비선형 곡선을 구한 후, 120분의 위잔류율을 예측함으로써 90분 이후의 지연영상 촬영시간을 절약할 수 있는지에 대하여 알아보았다. 대상 및 방법 : 환자들은 74 MBq (2 mCi) Tc-99m DTPA가 들어 있는 계란찜을 섭취한 직후 촬영을 시행하였다. 환자들을 반위배출시간에 따라 두 군으로 나누어 후향적으로 연구하였다. Group I은 반위배출시간이 90분 이하($T_{1/2}\;{\leq}90\;min$)인 51명(남자 21명, 여자: 30명, 평균나이: $44.6{\pm}13.5$세)이었고, Group II는 90분 초과 120분 이하($90\;min)인 45명(남자: 15, 여자:30, 평균나이 $45.6{\pm}15.9$)이었다. 0, 15, 30, 45, 60, 75, 90분에서의 위잔류율을 측정하여 비선형 곡선인 단순지수함수, power exponential function, modified power exponential function을 구하였고, 또한 50, 75, 90분의 측정치로 후기 단순지수함수를 구하였다($MATLAB^{\circledR}$ 5.3). 얻어진 함수식을 통해 120분에서의 위잔류율 예측치를 구한 후, 120분 측정치와의 상관관계를 알아보았다. ($MedCalc^{\circledR}$ 6.0). 결과: 120분 위잔류율의 측정치와 예측치의 상관계수(r)는 각각의 함수식에 따라 다음과 같다; 단순지수함수 (Group I: 0.8858, Group II: 0.5982, p<0.0001), power exponential function (Group I: 0.8755, Group II: 0.6008, p<0.0001), modified power exponential function (Group I: 0.8892, Group II: 0.5882, p<0.0001), 후기 단순지수함수 (Group I:0.9085, Group II:0.6832, p<0.0001). Group I에서만 함수식 모두에서 측정치와 예측치 간에 통계학적으로 의미있게 강한 상관관계를 보였다. 각 상관계수 간에 유의한 차이는 없었으나 후기지수함수식이 다른 함수식에 비하여 변수(parameter)와 입력될 측정치의 개수가 적어 예측치를 구하기가 간편하였다. 결론: 반위배출 시간이 90분 이하인 경우에 120분에서의 위잔류율을 예측할 수 있어 90분 이후의 촬영시간을 절약할 수 있다. 또한, 후기지수함수식이 다른 함수식에 비하여 예측치를 구하기가 간편하므로 임상적으로 더 유용하다.

• Journal of Animal Science and Technology
• /
• 제55권6호
• /
• pp.489-500
• /
• 2013

Daily milk yields on test days were estimated using morning or afternoon partial milk yields collected by official agencies and the accuracy of the estimates was determined. Test-day data for milk yields consisted of 3,156,734 records of AM/PM partial milking measurements of 255,437 milking Holstein cows from 3,708 farms collected from December 2008 to April 2013. A linear regression model (LRM) was applied to estimate daily milk yields using alternate AM/PM milk yield records within lactation stages, milking intervals, and parities on every daily milk yield. The alternate statistical approach was a non-linear hierarchical model (NHM) in which Brody's growth function was implemented by reflecting an animal's physiological milk production cycle. When compared with LRM, daily milk yields predicted by the NHM were assumed to be functionally related to day in milk (or lactation) stage, milking intervals, and partial milk yields. Since the results were in terms of accuracies based on comparisons of different statistical models, accuracies of estimates of daily milk yields by NHM were close to those determined by the LRM. The average of these accuracies was 0.94 for AM partial milk yields and 0.93 for PM partial milk yields for first calving cows. However, the accuracies of AM/PM milk yield estimations from cows under a calving stage higher than the first parity were 0.96 and 0.95, respectively. Correlations between the estimated daily milk yields and the actual daily milk yields ranged from 0.96~0.98. These accuracies were lower for unbalanced AM/PM milking intervals and the first calving cows. Overall, prediction of daily milk yields by NHM would be more appropriate than by LRM due to its flexibility under different milk yield-related circumstances, which provides an idea of the functional relationship between milking intervals and days in milk with daily milk yields from statistical viewpoints.

• Radiation Oncology Journal
• /
• 제34권2호
• /
• pp.135-144
• /
• 2016

Purpose: The purpose of this study was to evaluate the efficacy of art therapy to control fatigue in cancer patients during course of radiotherapy and its impact on quality of life (QoL). Materials and Methods: Fifty cancer patients receiving radiotherapy received weekly art therapy sessions using famous painting appreciation. Fatigue and QoL were assessed using the Brief Fatigue Inventory (BFI) Scale and the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) at baseline before starting radiotherapy, every week for 4 weeks during radiotherapy, and at the end of radiotherapy. Mean changes of scores over time were analyzed using a generalized linear mixed model. Results: Of the 50 patients, 34 (68%) participated in 4 sessions of art therapy. Generalized linear mixed models testing for the effect of time on mean score changes showed no significant changes in scores from baseline for the BFI and FACIT-F. The mean BFI score and FACIT-F total score changed from 3.1 to 2.7 and from 110.7 to 109.2, respectively. Art therapy based on the appreciation of famous paintings led to increases in self-esteem by increasing self-realization and forming social relationships. Conclusion: Fatigue and QoL in cancer patients with art therapy do not deteriorate during a period of radiotherapy. Despite the single-arm small number of participants and pilot design, this study provides a strong initial demonstration that art therapy of appreciation for famous painting is worthy of further study for fatigue and QoL improvement. Further, it can play an important role in routine practice in cancer patients during radiotherapy.

• 천문학회지
• /
• 제48권4호
• /
• pp.213-228
• /
• 2015

The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 6300³ gravitating particles in a cubic box of L_box = 3150 h⁻¹Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to M_s = 2.7 × 10¹¹h⁻¹M_⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln(1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation function of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine μ compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4.