• Steel and Composite Structures
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• 제31권5호
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• pp.469-488
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• 2019

We in this paper study nonlinear bending of a functionally graded porous nanobeam subjected to multiple physical load based on the nonlocal strain gradient theory. For more reasonable analysis of nanobeams made of porous functionally graded magneto-thermo-electro-elastic materials (PFGMTEEMs), both constituent materials and the porosity appear gradient distribution in the present expression of effective material properties, which is much more suitable to the actual compared with the conventional expression of effective material properties. Besides the displacement function regarding physical neutral surface is introduced to analyze mechanical behaviors of beams made of FGMs. Then we derive nonlinear governing equations of PFGMTEEMs beams using the principle of Hamilton. To obtain analytical solutions, a two-step perturbation method is developed in nonuniform electric field and magnetic field, and then we use it to solve nonlinear equations. Finally, the analytical solutions are utilized to perform a parametric analysis, where the effect of various physical parameters on static bending deformation of nanobeams are studied in detail, such as the nonlocal parameter, strain gradient parameter, the ratio of nonlocal parameter to strain gradient parameter, porosity volume fraction, material volume fraction index, temperature, initial magnetic potentials and external electric potentials.

• Steel and Composite Structures
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• 제42권3호
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• pp.375-388
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• 2022

In this work, limit elastic speed analysis of functionally graded porous rotating disks has been reported. The work proposes an effective approach for modeling the mechanical properties of a porous functionally graded rotating disk. Four different types of porosity models namely: uniform, symmetric, inner maximum, and outer maximum distribution are considered. The approach used is the variational principle, and the solution has been achieved using Galerkin's error minimization theory. The study aims to investigate the effect of grading indices, aspect ratio, porosity volume fraction, and porosity types on limit angular speed for uniform and variable disk geometries of constant mass. To validate the current study, finite element analysis has been used, and there is good agreement between the two methods. The study yielded a decrease in limit speed as grading indices and aspect ratio increase. The porosity volume fraction is found to be more significant than the aspect ratio effect. The research demonstrates a range of operable speeds for porous and non-porous disk profiles that can be used in industries as design data. The results show a significant increase in limit speed for an exponential disk when compared to other disk profiles, and thus, the study demonstrates a range of FG-based structures for applications in industries that will not only save material (lightweight structures) but also improve overall performance.

• 한국조경학회지
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• 제34권5호
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• pp.76-83
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• 2006

The purpose of this study was to investigate the performance of porous grass block. For the investigation, Festuca arundinacea and Zoysia japonica 'Zenith' were planted, and the volume of evapotranspiration and remains were examined based on different materials in the water tank in the experiment of Festuca arundinacea, the volume of water storage of treatment with perlite ($10.84{\iota}/m^2$) was higher than that with drainage ($7l/m^2$). The difference between the two was $3.84/m^2$. The drainage treatment without water storage capacity showed the higher degree of dryness in turf grass. The volume of evapo-transpiration of treatment with perlite was the highest (21.57mm/week). The volume of evapotranspiration of treatment with sand was 19.57mm/week, and with treatment with drainage was 18.24mm/week. Based on the measured volume of daily evapotranspiration of $2.60{\sim}3.08mm\;d^{-1}$, it was determined that the unit with water storage capacity would store water of one to two days usage compared to unite without such storage capacity. In the experiment of Zoysia japonica 'Zenith', the volume of water storage of treatment with perlite was $10.77l/m^2$ which was similar to the former experiment. The volume of evapotranspiration of treatment with perlite and sand were 21.64mm/week and 20.64mm/week, respectively. In case of airtight water tank, the volume was measured as 22.06mm/week. Each treatment has no notable difference in the volume of evapotranspiration. In conclusion, from the investigation in this study, porous grass block with water tank was found to be effective in plant growth under low irrigation. As the ecological area ratio and vegetated porous pavement have became more emphasized, additional study of rain infiltration and reservoir effect are needed in the future.

• Journal of Korean Neurosurgical Society
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• 제54권3호
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• pp.175-182
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• 2013

Objective : Intracavitary injection of beta-emitting radiation source for control of cystic tumors has been tried with a benefit of localized internal radiation. The authors treated cystic brain tumor patients with Holmium-166-chitosan complex (Ho-166-chico), composed of a beta-emitting radionuclide Holmium-166 and biodegradable chit polymer, and evaluated the safety and effective measurement for response. Methods : Twenty-two patients with recurrent cystic brain tumor and/or located in a deep or eloquent area were enrolled in this pilot study. The cyst volume and wall thickness were determined on CT or MRI to assess radiological response. The activity of Ho-166-chico injected via Ommaya reservoir was prescribed to be 10-25 Gy to the cyst wall in a depth of 4 mm. Results : There was neither complications related to systemic absorption nor leakage of Ho-166-chico in all 22 patients. But, two cases of oculomotor paresis were observed in patients with recurrent craniopharyngioma. Radiological response was seen in 14 of 20 available follow-up images (70%). Seven patients of 'evident' radiological response experienced more than 25% decrease of both cyst volume and wall thickness. Another 7 patients with 'suggestive' response showed decrease of cyst volume without definitive change of the wall thickness or vice versa. All patients with benign tumors or low grade gliomas experienced symptomatic improvement. Conclusion : Ho-166-chico intracavitary radiation therapy for cystic tumor is a safe method of palliation without serious complications. The determination of both minimal effective dosage and time interval of repeated injection through phase 1 trial could improve the results in the future.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.14-21
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• 2008

Synthetic gas is defined as reformed gas from hydrocarbon-based fuel and the major chemical species of the synthetic gas are $H_2$, CO and $N_2$. Among them, hydrogen from synthetic gas is very useful species in chemical process such as combustion. It is a main reason that many studies have been performed to develop an effective reforming device. Furthermore, other technologies have been studied for synthetic gas application, such as the ESGI(Exhaust Synthetic Gas Injection) technology. ESGI injects and burns synthetic gas in the exhaust pipe so that heat from hydrogen combustion helps fast warmup of the close-coupled catalyst and reduction of harmful emissions. However, it is very hard to understand combustion characteristic of hydrogen under low oxygen environment and complicated variation in chemical species in exhaust gas. This study focuses on the characteristics of hydrogen combustion under ESGI operating conditions using a CVC(Constant Volume Chamber). Measurements of pressure variation and flame speed have been performed for various oxygen and hydrogen concentrations. Results have been analyzed to understand ignition and combustion characteristics of hydrogen under lower oxygen conditions. The CVC experiments showed that under lower oxygen concentration, amount of active chemicals in the combustion chamber was a crucial factor to influence hydrogen combustion as well as hydrogen/oxygen ratio. It is also found that increase in volume fraction of oxygen is effective for the fast and stable burning of hydrogen by virtue of increase in flame speed.

• 한국정보과학회논문지:시스템및이론
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• 제27권8호
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• pp.691-700
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• 2000

볼륨 데이타에 대한 팔진트리와 같은 계층 자료구조를 사용하는 광선 추적법은 모든 광선이 계층구조를 순회하는 것으로 인한 중복된 계산을 포함하고 있으며, 좋은 화질의 영상을 얻기 위한 3차원 보간으로 인하여 많은 계산 비용을 요구한다. 본 논문은 볼륨 데이타의 계층구조에 대한 중복된 방문을 피하고， 오직 한 번만 계층구조를 방문하면서 효과적으로 광선의 리샘플링 지점을 결정하여 색상과 투병도를 구하는 볼륨 렌더링 알고리듬을 제안한다. 이 방법은 물체 순서로 광선 추적법을 수행하면서, 각 복셀 주위에서의 리샘플링 지점을 점진적으로 찾아가면서 각 슬라이스 상에서의 2차원 보간에 기반을 둔 리샘플링을 수행한다. 또한 물체 순서 렌더링에서는 조기 광선 종결과 같은 최적화 기법을 구현하기 힘든데, 영상공간에서의 동적 자료구조를 이용하여 이를 효과적으로 해결하였다 본 논문이 제안한 방법은 구현하기 쉽고 속도 향상을 위하여 추가적으로 요구되는 메모리가 매우 적기 때문에 광선 추적법과 쉬어 와핑 방법 사이의 성능 차이를 메워주는 효과적인 방법으로 사용될 수 있을 것이다.

• Archives of Plastic Surgery
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• 제33권1호
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• pp.75-79
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• 2006

The upper and lower lateral cartilages provide the key to the lower cartilaginous portion of the nose. Lifting the cartilages is essential procedure for correction of unilateral cleft lip nose deformity. After correction of cleft lip nose deformity, authors used acoustic rhinometry (AR) to compare the lower nasal cavity of cleft side with non-cleft side. AR is a well known new, non-invasive diagnostic technique in which nasal geometry is assessed by means of acoustic reflection. From June 1996 to January 2004, we performed acoustic rhinometric analysis after correction of unilateral cleft lip nose deformity. This study involved 40 children of age ranged from 3 months to 8 years. Subjects were divided into the group of incomplete unilateral cleft lip nose deformity(20 subjects), and the group of complete unilateral cleft lip nose deformity(20 subjects). Results show that lower nasal cavity volume between non-cleft side and cleft side has no difference, and better results were obtained when nasal molding prong was applied at cleft side nostril. The results between incomplete type and complete type have no significant difference. In conclusion, AR is an effective method to calibrate cross sectional area and nasal cavity volume of unilateral cleft lip nose deformity, and furthermore effective in comparing the volume of cleft side with non-cleft side after unilateral cleft lip nose deformity correction with lifting the lower lateral cartilages to the upper lateral cartilages.

• 한국측량학회지
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• 제18권4호
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• pp.343-350
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• 2000

본 연구는 해안 방파제 공사에서 사석의 투하방향 및 물량을 DGPS ＆ Echo-Sounder를 이용하여 확인하고 앞으로의 사석투하물량의 계산에 대하여 다루고 있다 방파제 공사에 있어서 사석 투하는 제방 중심선에 대하여 부표를 띄어놓고 이루어지며, 사석 투하를 실시한 후 측간, 측심연 잠수부 등에 의하여 사석의 투하 형태 및 방향에 대한 확인 작업을 실시하게 된다. 그러나 사석 투하 지역전체에 대하여 이와 같은 방법으로 데이터를 취득하고 투하물량을 산정 하는 것은 많은 시간과 인원을 필요로 하며, 정확도에 있어서도 효율적인 방법이라 할 수 없다. 이러한 문제에 대한 해결 방법으로 본 연구에서는 DGPS ＆ Echo-Sounder를 이용하여 사석투하 지역에 대한 측량을 실시하고 사석 투하깊이, 방향 및 물량 등을 계산하여 사석 투하공정을 확인하였으며, 앞으로의 투하 물량에 대한 계산을 실시함으로서 DGPS & Echo-Sounder에 의한 효율적 사석투하 관리방법을 제시하고자 하였다.

• 한국전문물리치료학회지
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• 제16권3호
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• pp.1-8
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• 2009

It is important to find the effective position for cough and sputum clearance in respiratory physical therapy. The purpose of this study was to compare the changes in peak expiratory flow (PEF), forced expiratory volume in 1 second ($FEV_1$), and peak cough flow (PCF) related to functional level and measurement position in patients with Duchenne muscular dystrophy. Twenty one subjects were classified into three functional levels, and measurements was undertaken in three different measurement positions (upright sitting, $45^{\circ}$ reclining and supine). Vitalograph PEF/FEV DIARY was used to measure PEF and $FEV_1$, and Ferraris Pocket Peak was used to measure PCF. Mixed two-way analysis of variance and Bonferroni post-hoc test were used for statistical analysis. The results of the study were as follows: 1) Significant main effects for measurement position were found. 2) PEF was the highest in upright sitting, followed by $45^{\circ}$ reclining, and supine in order. 3) $FEV_1$ in upright sitting and $45^{\circ}$ reclining were significantly greater compared with that in supine. 4) PCF in upright sitting and $45^{\circ}$ reclining were significantly greater compared with that in supine. 5) No significant main effects for functional level were found in PEF, $FEV_1$, and PCF. 6) No significant functional level by measurement position interactions were found in PEF, $FEV_1$, and PCF. Therefore, it is concluded that upright sitting and $45^{\circ}$ degree reclining positions are recommended for effective cough and sputum clearance.

• Medical Lasers
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• 제10권4호
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• pp.220-228
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• 2021

Background and Objectives In designing a resistance exercise program, intensity, rest, and exercise volume are important. Many studies have been conducted to find the most suitable resistance exercise program incorporating the above, and in particular, many prior studies have been conducted on intensity. This study attempted to determine the effective volume of exercise by analyzing the number of repetitions performed at intensities of 65% one-repetition maximum (1RM) and 75% 1RM during the bench press exercise, and the electromyography (EMG) response of the agonist muscle. Materials and Methods Eight males in their 20s were selected as study subjects and they performed five sets of bench presses at two levels of intensity (65% 1RM, 75% 1RM). The following results were obtained by measuring the number of repetitions and the EMG response according to the exercise intensity and sets during the workout. Results First, the number of repetitions showed a sharp drop from the first set to the third set at 65% 1RM intensity and showed no change in the fourth and fifth sets. At 75% 1RM intensity, the intensity of hypertrophy showed a gradual decrease from the first set to the fifth set. Second, at 75% 1RM exercise intensity, the pectoralis major, anterior deltoid and triceps brachii showed high muscle activity, and the activity of the anterior deltoid continued to increase from the first set to the fourth set at 65% 1RM intensity, and from the first set to the fifth set at 75% 1RM. Conclusion It was found that during the bench press exercise, three minutes of rest at 75% 1RM intensity, five sets of five sets, one minute rest at 65% 1RM intensity, and three sets of the exercise were effective.