• 한국자동차공학회논문집
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• 제6권4호
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• pp.76-85
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• 1998

Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

• Journal of Korean Neurosurgical Society
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• 제46권3호
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• pp.252-256
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• 2009

Meningioangiomatosis (MA) is a rare congenital tumor that occurs mostly in 5-15 year old children. There have been only 5 cases previously reported that described the cystic nature within these tumors. We present a case of a MA accompanied by a separate macrocyst. A normally developed 2 year-old female patient presented with partial and generalized seizures. The brain computerized tomogram and magnetic resonance imaging revealed the presence of a calcified mass accompanied by a cyst in the right parietal area, surrounded by low density and high attenuation edema and hemorrhage. Upon right parietal craniotomy, a $1.6cm{\times}1.2cm{\times}0.5cm$ sized plate-like, gray-white, slightly hard mass was seen and it was completely excised. Approximately 1 cm from the mass in the anterior lateral direction, a cyst was found and subsequent biopsy of the cyst wall revealed no tumor tissue, and therefore the cyst was not removed. Pathologic report demonstrated the meningioangiomatosis. Follow up examination 2 years later showed no recurrence of the tumor, and there was no evidence of neurological deficits. Authors suggest that cysts that arise in the surrounding tissues of tumors may not be tumor cysts, and do not require surgical removal.

• 천문학회보
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• 제36권1호
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• pp.29.2-29.2
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• 2011

Although stellar flares have a long history of observations, there are few concrete understanding about underlying physical processes and meaningful correlations with other stellar properties. Most of previous observations dealt with only a small number of sample stars, and therefore not sufficient to support generalized statistical studies. Based on one-month long MMT time-series observations of the open cluster M37, we monitored light variations of nearly 2,500 M-dwarf stars and successfully identified 606 flare events from 422 stars. This is a rare attempt to estimate true flare rates and properties among many stars of the same age and mass group. For each flare, we considered both observational and physical parameters including flare shape, duration before and after the peak, baseline magnitude before and after the peak, peak magnitudes, total energy and peak energy, etc. We find significant correlations between some of key parameters over a wide range of energy ($Er=10^{32}{\sim}10^{36}ergs$). For instance, regardless of stellar luminosities, the energy power spectrum of flares can be approximated by a power law (${\beta}=0.83-0.97$). This suggests that flares follow similar physical mechanisms for atmospheric heating and cooling among these low-mass stars. From this MMT data set, we derived an average flaring rate of $0.019 hr^{-1}$ among flare stars and $0.003 hr^{-1}$ for all M-dwarf candidates. We will report the details of our analysis and discuss physical implications.

• Journal of Yeungnam Medical Science
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• 제34권2호
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• pp.275-278
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• 2017

Small cell lung carcinoma (SCLC) is a cancer that shows aggressive behavior, early spread to distant sites, and frequent association with distinct paraneoplastic syndromes. Spontaneous remission of cancer, particularly of SCLC, is a rare biological event. Cases involving spontaneous regression of SCLC were reported, and were associated with paraneoplastic syndromes of the nervous system. This article reports on a 78-year-old man with SCLC in remission, with neurological symptoms. The patient visited the hospital because of generalized weakness, and imaging studies revealed a mass in the lower lobe of the left lung, pathological evaluation showed SCLC. The patient refused oncologic treatment and was treated only with conservative care. In follow-up study the diameter of the mass had decreased from initial 32 mm, 9 months after admission to 20 mm, 17 months after admission to 13 mm. The patient kept complaining of generalized weakness, dizziness, and paresthesia of limbs. We assumed that, in this case, the spontaneous remission of lung cancer was related to the immunologic response directed against the tumor, which is believed to be an important factor in the pathogenesis of paraneoplastic neurologic syndromes.

• Structural Engineering and Mechanics
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• 제43권5호
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• pp.691-709
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• 2012

This paper provides a variety of viewpoints to illustrate the mechanism of the deck-stay interaction with the appropriate initial shapes of cable-stayed bridges. Based on the smooth and convergent bridge shapes obtained by the initial shape analysis, the one-element cable system (OECS) and multi-element cable system (MECS) models of the Kao Ping Hsi Bridge in Taiwan are developed to verify the applicability of the analytical model and numerical formulation from the field observations in the authors' previous work. For this purpose, the modal analysis of the two finite element models are conducted to calculate the natural frequency and normalized mode shape of the individual modes of the bridge. The modal coupling assessment is also performed to obtain the generalized mass ratios among the structural components for each mode of the bridge. The findings indicate that the coupled modes are attributed to the frequency loci veering and mode localization when the "pure" deck-tower frequency and the "pure" stay cable frequency approach one another, implying that the mode shapes of such coupled modes are simply different from those of the deck-tower system or stay cables alone. The distribution of the generalized mass ratios between the deck-tower system and stay cables are useful indices for quantitatively assessing the degree of coupling for each mode. These results are demonstrated to fully understand the mechanism of the deck-stay interaction with the appropriate initial shapes of cable-stayed bridges.

• The Korean Journal of Pain
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• 제36권2호
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• pp.184-194
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• 2023

Background: Degenerative lumbar spondylolisthesis (DLS) is frequently associated with lumbar spinal stenosis (LSS) and conservative treatments such as epidural steroid injection do not have long-term benefits in LSS patients with DLS. This study evaluated the effectiveness of percutaneous epidural neuroplasty using a balloon catheter in patients with LSS and DLS. Methods: Patients' sex, age, body mass index, diabetes, hypertension, stenosis grading, pain duration, location, pain intensity, and medications were retrieved from electronic medical records. At 1, 3, and 6 months following the procedure, data on pain severity, medication usage, and physical functional status were analyzed. A generalized estimating equations model was used at the six-month follow-up. Patients were divided into those with DLS (the spondylolisthesis group) and those without DLS (the no spondylolisthesis group) to evaluate whether the effects of percutaneous epidural neuroplasty using a balloon catheter were different. Results: A total of 826 patients were included (spondylolisthesis: 433 patients, 52.4%; no spondylolisthesis: 393 patients, 47.6%). Age, body mass index, hypertension, pain location, and stenosis grading were statistically different between the two groups. The generalized estimating equations analyses with unadjusted and adjusted estimation revealed a significant improvement in the estimated mean numerical rating scale of pain intensities compared to that at baseline in both groups (P < 0.001). Any adverse events that occurred were minor and temporary. Conclusions: Percutaneous epidural neuroplasty using a balloon catheter may be an alternative treatment option for patients with chronic LSS, regardless of accompanying DLS, who have had failed conservative management.

• 한국언론정보학보
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• 제67권
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• pp.119-151
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• 2014

커뮤니케이션학에서 통약가능한 이론적 대중매체체계론이 부재하다는 점은 비교연구를 비롯한 경험연구에서 난점으로 남아있었다. 본 연구는 하버마스의 2단계 사회론을 수정한 수정된 2단계 사회론을 바탕으로 정적 일반대중매체체계론을, 루만의 경계이론과 들뢰즈 가타리의 배치이론을 종합한 경계배치이론을 바탕으로 동적 일반대중매체체계론을 제안한다. 정적 일반대중매체체계론에서 대중매체체계는 일반화된 언어를 조정매체로 하는 문화체계의 하위사회체계로서 여타 하위사회체계 및 생활세계와 상호침투한다. 동적 일반대중매체체계론에서 대중매체체계는 다른 모든 하위사회체계의 경계로서 하위사회체계의 자기관계적 관찰을 생활세계에 의한 타자관계적 관찰과 접목시킨다. 또 대중매체체계는 체계와 생활세계 간의 상호침투를 매개한다. 특히 대중매체체계에서의 수행은 체계를 생활세계로 탈영토화하고 생활세계를 체계로 재영토화한다. 일반대중매체체계론은 다양한 경험적 대중매체체계론에 통약가능성을 제공해주고 편향되게 연구대상을 설정하지 않도록 도움을 줄 것으로 기대된다.

• 터널과지하공간
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• 제32권5호
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• pp.312-326
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• 2022

암반의 표준 파괴기준식의 하나로 인정받고 있는 일반화된 Hoek-Brown (GHB) 식은 암반공학적 활용에 특화되어 있으며 넓은 범위의 암반조건을 고려할 수 있다. 이에 따라 암반 구조물의 안정성 해석과정에서 GHB 식을 적극적으로 활용하기 위한 많은 연구 노력이 진행 중이다. 이 연구에서는 탄소성 해석법의 일종인 slip-line 해석법을 GHB 파괴기준식과 결합하여 원형터널 주변의 소성반경과 응력분포를 간편하게 계산할 수 있는 해석적 수식들을 유도하였다. 관련 수식 유도과정에서는 파괴 후 거동으로 완전 소성 거동을 가정하였고, 초기지압은 정수압 상태로 가정하였다. 이 연구를 통하여 소성반경은 터널 벽면과 탄성-소성 경계면에 대응되는 두 접선 마찰각을 이용하여 해석적으로 계산할 수 있음을 밝혔다. 또한 유도한 해석 식들을 이용하여 계산한 소성반경과 응력분포는 2008년에 발표된 Lee & Pietruszczak의 수치해석적 방법의 결과와 일치함을 보였다. 이 논문의 후반부에서는 유도한 해석 식을 활용하여 암반의 양호도가 소성영역의 크기, 응력분포, 접선마찰각의 변화에 미치는 영향을 분석하였다.

• Nutrition Research and Practice
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• 제13권3호
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• pp.214-221
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• 2019

BACKGROUNDS/OBJECTIVES: Cancer treatment may lead to significant body composition changes and affect growth and disease outcomes in pediatric cancer patients. This prospective study aimed to evaluate short- and long-term body compositions changes focused on body fat during the first year of cancer treatment in children. SUBJECTS/METHODS: A prospective study was conducted in 30 pediatric cancer patients (19 hematologic malignancies and 11 solid tumors) and 30 age- and sex-matched healthy controls. Anthropometric measurements and body composition analysis using whole body dual energy X-ray absorptiometry were performed at baseline and 1, 6, and 12 month(s) of cancer treatment. Kruskal-Wallis tests, Wilcoxon paired t tests, and generalized estimation equation (GEE) were applied for statistical analysis. RESULTS: At baseline, no differences in weight, height, body mass index, abdominal circumferences, body fat, and fat-free mass were observed between 30 controls and 30 pediatric cancer patients. Total fat mass (P < 0.001) and body fat percentage (P = 0.002) increased significantly during the first month, but no changes were observed from 1 to 12 months; however, no changes in the total mass were observed during the first year of cancer treatment. Meanwhile, the total fat-free mass decreased during the first month (P = 0.008) and recovered between 6 and 12 months of follow-up (P < 0.001). According to GEE analysis, there was a significant upward trend in body fat percentage during the first year, especially the first month, of cancer treatment in children with hematologic malignancies, but not in those with solid tumors. CONCLUSIONS: Our results indicate that cancer treatment is related to significant body composition changes and rapid body fat gain, particularly during the first month after initiating cancer treatment, in children with hematologic malignancies. Therefore, individualized dietary strategies to prevent excessive fat gain are needed in pediatric cancer patients for better outcomes.

• Coupled systems mechanics
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• 제3권3호
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• pp.247-265
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• 2014

This article discusses the dynamic response of Bernoulli-Euler straight beam with angular elastic supports subjected to moving load with variable velocity. A new engineering approach for determination of the dynamic effect from the moving load on the stressed and strained state of the beam has been developed. A dynamic coefficient, a ratio of the dynamic to the static deflection of the beam, has been defined on the base of an infinite geometrical absolutely summable series. Generalization of the R. Willis' equation has been carried out: generalized boundary conditions have been introduced; the generalized elastic curve's equation on the base of infinite trigonometric series method has been obtained; the forces of inertia from normal and Coriolis accelerations and reduced beam mass have been taken into account. The influence of the boundary conditions and kinematic characteristics of the moving load on the dynamic coefficient has been investigated. As a result, the dynamic stressed and strained state has been obtained as a multiplication of the static one with the dynamic coefficient. The developed approach has been compared with a finite element one for a concrete engineering case and thus its authenticity has been proved.