• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.75-75
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• 2010

단일벽 탄소나노튜브(SWNT)는 뛰어난 물리적 성질과 화학적 안정성을 가지고 있어서 다양한 분야의 응용이 기대되어 폭넓은 연구가 진행 되고 있다. 특히 SWNT의 전기적 및 기계적 특성들은 SWNT의 직경 및 뒤틀림도(chirality)에 의해 크게 좌우되기 때문에, 합성하는 단계에서 직경 또는 chirality를 제어에 관한 많은 이론적 연구가 진행되어 왔으며, 최근에는 초기 SWNT의 핵생성 단계에서의 촉매의 거동 및 상호 연관성 등에 관한 실험적인 연구결과들이 속속 보고되고 있는 실정이다. 하지만, 아직도 이에 관한 더욱 다양하고 활발한 연구 접근 및 결과들이 필요한 시점이다. 상기 배경을 바탕으로 본 연구에서는 균일한 직경을 갖는 SWNT의 합성을 위한 기초연구로서 SWNT의 직경과 촉매나노입자의 크기의 상호 연관성에 대해 체계적으로 조사하였다. 우선 SWNT합성을 위한 촉매나노입자를 얻기 위해 페리틴(ferritin)용액의 농도 및 스핀코팅 조건을 변화시킴으로써 기판 위에 분산농도를 제어한 후, 대기 열처리를 통하여 촉매나노입자의 농도를 제어하였다. 나노입자의 평균직경은 4 nm 정도로 비교적 균일하였으며, 고농도의 촉매입자는 SWNT의 다발화(bundling)를 유발하였다. 따라서, SWNT와 나노입자 직경의 상호연관성을 조사하기 위해서는 단분산(monodispersed) 된 나노입자를 이용하였으며, 아르곤 분위기에서 추가적으로 고온($900^{\circ}C$) 열처리를 실시함으로써 나노입자의 크기감소를 도모하였다. 실험결과, 열처리 시간의 증가에 따라 입자크기가 감소함을 확인하였으며, 이는 나노입자의 증발에 의한 것으로 예상된다. 다음으로는 열처리를 통하여 직경이 제어된 나노입자를 이용하여 SWNT를 합성한 후 SWNT와 촉매크기 사이의 크기 관계를 조사하였다. SWNT의 합성은 메탄을 원료가스로 열화학증기증착법을 이용하였고, 합성기판으로는 산화실리콘웨이퍼와 퀄츠기판을 이용하였다. 성장한 SWNT의 직경은 AFM을 이용하여 측정하였으며, 퀄츠기판에 수평배향 성장시킨 SWNT를 3차원 구조의 기판으로 전사(transfer)하여, 라만분석이 용이하도록 하였다.

• 한국노년학
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• v.38 no.2
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• pp.309-327
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• 2018

Meta-analysis was conducted on 34 studies reported in Korea from February 2007 through March 2017 to systematically integrate factors of aging anxiety of the middle and old aged. The variables related to aging anxiety were divided into 6 groups of variable, and the effect sizes were computed for each variable of their groups. The results are as follows. First, the total effect size showed the middle effect size, and the effect size according to the variable group showed the largest effect size for the negative psychological variable group, followed by the positive psychological variable, the social variable, the physical variable, the familial variable and the demographic variable. Second, the largest effect size of the sub-variables showed psychological well-being and death anxiety. As described above, suggesting that these variables may have a strong influence on aging anxiety among the variables related to aging anxiety because the psychological well-being and death anxiety were shown as the largest effective variables related to aging anxiety.

• Clean Technology
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• v.19 no.4
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• pp.370-378
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• 2013

This review has shown the capability of MOFs and ZIFs materials to adsorb $CO_2$ under typical PSA temperatures and pressures. The usual operating conditions are adsorption temperatures of $15{\sim}40^{\circ}C$ and adsorption pressures of 4~6 bar based on numerous PSA processes which are widely employed in gases industry for adsorptive separation of $CO_2$. The extent of $CO_2$ adsorption on the microporous materials depends on the metal species and organic linkers existing in the frameworks. The pore size and the surface area, and the process variables are the key parameters to be associated with the efficiency of the adsorbents, particularly adsorption pressures if other variables are comparable each other. The MOFs and ZIFs materials require high pressures greater than 15 bar to yield significant $CO_2$ uptakes. They possess a $CO_2$ adsorption capacity which is very similar to or less than that of conventional benchmark adsorbents such as zeolites and activated carbons. Consequently, those materials have been much less cost-effective for adsorptive $CO_2$ separation to date because of very high production price and the absence of commercially-proven PSA processes using such new adsorbents.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.160-164
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• 2008

A two-month-old girl with a history of an incidental arachnoid cyst in the prenatal period (38 weeks) presented with persistent irritability. A follow-up computed tomographic (CT) scan revealed an enlarged arachnoid cyst with hydrocephalus. We performed craniotomy and fenestration, but the cyst size did not decrease, and hydrocephalus had worsened on a follow-up CT scan performed 13 months after fenestration. The patient was treated with cystoperitoneal shunting. Follow-up magnetic resonance imaging (MRI) performed 5 years later revealed that the arachnoid cyst had decreased in size and that the hydrocephalus had resolved. Enlarging arachnoid cysts are not common, and optimal surgical treatment is uncertain. Based on the features of this case, we believe cystoperitoneal shunting is an advisable surgical intervention for patients with enlarging arachnoid cysts presenting with hydrocephalus.

• The Journal of Sustainable Design and Educational Environment Research
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• v.14 no.2
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• pp.37-44
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• 2015

The purpose of this study is to propose the calculation model of CCTV monitor size for school. Literature review analyzed the concept and technical characteristics of CCTV system including equation of object size calculation. Case study showed that the sizes of CCTV monitors installed in the security offices of the six object schools were 19 inches on average. And the numbers of monitor screen partitions were at least 12 on average. Due to too many partitions in small monitors of approximately 19 inches, the faces of the objects of filming in each screen could not be properly identified. Experimental test presented that the vertical length of face image clearly recognized on the screen is at least 20mm. Based on the result, this paper developed the equation for calculating monitor size. Pilot test said that 27inch Monitor is needed for 4 screens. The practitioners of school districts and schools can make appropriate CCTV system environments considering the their own CCTV system conditions.

• 한국노년학
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• v.38 no.1
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• pp.65-82
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• 2018

The purpose of this study is to statistically summarize the effect sizes using meta-analysis of various Kigong programs implemented on the subject of physical health of the elderly. Including 23 academic journal studies and 11 thesis studies reported domestically until 2016, a total of 34 studies were selected and analyzed to verify the effect sizes of programs, program types, measuring variables, and activity elements. The findings are as follows. First, it was found that the programs were midium effective with overall average effect size showing .748(p<.001). A program of Tai-Chi indicated the largest effect size of .836(p<.001). In terms of measuring variables, physical strength showed the largest effect size of .806(p<.001). In terms of gender by group, it was found that groups consisting only of men indicated the largest effect size of 2.388(p<.001). As for effect size by group of disease state, normal group with showed the highest effect size of .804(p<.001). Second, in activity elements, 31~60 by the group size has the largest effect size of .873(p<.001), total number of sessions for 31~40 sessions indicated the largest effect value of .829(p<.001). As for number of sessions per week, 5 sessions showed largest effect value of .918(p<.001), in terms of activity time, 50 minutes showed large effect value of 1.391(p<.001). As summarized above, Kigong programs are midium effective for physical health of the elderly, as an activity elements to consider when configuring the program, for group size 31~60, 31~40 sessions in total, 5 sessions per week and 50 minutes per sessions were recommended.

• Journal of Chest Surgery
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• v.35 no.8
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• pp.611-615
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• 2002

Pneumoconiosis is fibrogenic disease, caused by inhalation of mineral dust. It is defined as the accumulation of dust in the lung and tissue reaction to its presence and the dust is considered to be an aerosal of solid and inanimate particles. It is among the most common and the most important occupational lung disease, especially in developing countries. It is required three prerequisites for making a clinical diagnosis of pneumoconiosis: 1) a full clinical and occupational history together with the result of physical examination; 2) previous X-ray for comparison; and 3) a clear understanding of the time scale involved in the progression of the diseases. Most pneumoconiosises are slow to evolve and changes in the appearances take many months -usually years- to occur. Pneumoconiosis is represented on a plain X-ray of the chest as multiple small round opacities, usually smaller than 1cm diameter. In 58 years old female patient, pneumoconiosis is manifested as $5{\times}4{\times}3$cm sized solitary pulmonary nodule without any occupational history and past history of exposure of dust. so we treated this case with right upper lobectomy. Therefore we report this case with a brief review of literatures.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.1-7
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• 2022

Recently, satellites equipped with high-performance electronics have required higher power consumption because of the advancement of satellite missions. For this reason, the size of the solar panel is gradually increasing to meet the required power budget. Increasing the size and weight of the solar panel is one of the factors that induce the elastic vibration of the flexible solar panel during the highly agile maneuvering of the satellite or the mode of vibration coupling to the satellite or the mode of vibration coupling to the micro-jitter from the on-board appendages. Previously, an additional damper system was applied to reduce the elastic vibration of the solar panel, but the increase in size and mass of system was inevitable. In this study, to overcome the abovementioned limitations, we proposed a high -damping yoke structure consisting of a superplastic SMA(Shape Memory Alloy) laminating a thin FR4 layer with viscoelastic tape on both sides. Therefore, this advantage contributes to system simplicity by reducing vibrations with small volume and mass without additional system. The effectiveness of the proposed superelastic SMA multilayer solar panel yoke was validated through free vibration testing and temperature testing using a solar panel dummy.

• Clean Technology
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• v.20 no.1
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• pp.28-34
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• 2014

In this study, we synthesized $TiO_2$ supports with nanosized crystalline structure by solvothermal method and prepared $TiO_2$ supported Pd-Cu catalysts. It was shown that the crystalline size of $TiO_2$ support in the catalyst influenced on the catalytic activity of nitrate reduction in water. The catalyst with the smaller crystalline size of $TiO_2$ support presented faster nitrate reduction rate, but had low nitrogen selectivity due to high pH environment of reaction medium during the reaction. Through injection of carbon dioxide as a pH buffer, the nitrogen selectivity increased by about 60%. Furthermore, we investigated that the relationships between the catalytic performance and the physicochemical properties of the prepared catalysts characterized by $N_2$ adsoprtion-desorption, X-ray diffraction (XRD), $H_2$-temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS).

• The Korean Journal of Financial Management
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• v.14 no.3
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• pp.57-72
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• 1997

우리나라의 기업들은 외국과는 달리 대주주와 소액주주간의 차등배당을 실시하는 독특한 배당정책을 가지고 있으며, 대주주들이 소액주주들보다 실제적으로 적은 배당금을 지급받는 형태로 운영되고 있다. 대주주들이 차등배당결정에 대한 거부권을 행사할 충분한 능력이 있음을 가정할 때 자신의 부를 감소시키는 배당정책을 스스로 허용하는 이유에 대한 의문이 제기된다. 본 연구는 이에 대한 최초의 연구로 차등배당 지급동기에 대하여 두가지 가능성을 제시하고자 한다. 첫째로, 한계세율가설을 들 수 있다. 이는 국내 과세제도가 대주주들에게 적은 배당을 지급하게끔 하는 동인으로 작용한다는 것이다. 우리나라의 과세정책하에서 소액주주들은 그들의 배당소득에 따른 분리과세를 적용받는 반면에 대주주들은 종합과세가 적용되기 때문에 대주주의 배당소득이 더 높은 종합과세율에 적용을 받는 한계소득이라면 대주주들은 소액주주보다 낮은 배당(또는 무배당)을 선호할 수 있을 것이다. 둘째로, 배당재원가설을 들 수 있다. 이는 기업의 수익이 모든 주주들에게 기존의 배당금과 비슷한 배당금을 지불할 정도로 충분치 않을 경우 차등배당을 실시할 수 있다는 것이다. 기업의 이익이 감소하였을 때 대주주에 대한 배당금을 줄임으로써 주식시장의 한계 투자그룹을 형성하고 있는 소액주주들에게는 이전과 비슷한 크기의 안정적인 배당금을 지급 하고자 한다는 것이다. 상기 두가지 가설에 대한 검증을 Logit모형을 이용하여 실증 분석하였으며, 그 결과 배당가능이익의 크기가 작을수록, 그리고 대주주의 한계소득세율이 높을수록 차등배당의 경향이 높은 것으로 나타나 세율과 기업의 수익성이 차등배당의 주요한 동인으로 작용하고 있는 것을 발견하였다.