• Journal of Korean Neurosurgical Society
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• 제44권1호
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• pp.52-56
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• 2008

Objective : The purpose of this study was to introduce our surgical experiences of scoliosis and to evaluate the effectiveness of anterior correction and fusion in adolescent idiopathic scoliosis (AIS). Methods : Between August 2004 and August 2007, four patients with AIS were treated with anterior segmental fusion and fixation at our hospital. Mean follow-up period was 9 (6-12) months. The average age was 14.0 (13-15) years. According to Lenke classification, three patients showed Lenke 1 curve and one patient with Lenke 5 curve. Single rod instrumentation was performed in one patient, dual rod instrumentation in one patient and combined rod instrumentation in two patients. Coronal Cobb measurements were performed on all curves in thoracic, thoracolumbar and, lumbar spine and the angle of hump was measured by a scoliometer pre- and postoperatively. Results : The average operative time was 394 minutes (255-525) with an average intraoperative blood loss of 1,225 ml (1,000-1,700). The mean period of hospital stay was 19.3 days and there was no complication related to the surgery. The mean Cobb angle was reduced from $43.3^{\circ}$ to $14.8^{\circ}$ (65.8% correction) postoperatively and the rib hump corrected less than $5^{\circ}$. All patients and their parents were satisfied with the deformity correction. Conclusion : Anterior spinal correction and fusion of AIS with Lenke 1 and 5 curve showed excellent deformity correction without any complications. In particular, we recommend anterior dual rod instrumentation because of mechanical stability, better control of kyphosis, and a higher fusion rate.

• Journal of Biosystems Engineering
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• 제41권3호
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• pp.221-231
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• 2016

Purpose: The objective of this study was to develop cushion curves models and analyze the cushioning performance of multi-layered corrugated structures (MLCS) using a method based on dynamic stress-energy relationship. Methods: Cushion tests were performed for developing cushion curve models under 12 combinations of test conditions: three different combinations of drop height, material thickness, and static stress for each of four levels of energy densities between 15 and $60kJ/m^3$. Results: Dynamic stress and energy density for MLCS followed an exponential relationship. Cushion curve models were developed as a function of drop height, material thickness, and static stress for different paperboards and flute types. Generally, the differences between the shock pulse (transmitted peak acceleration) and cushion curve (position and width of belly portion) for the first drop and the averaged second to fifth drop were greater than those for polymer-based cushioning materials. Accordingly, the loss of cushioning performance of MLCS was estimated to be greater than that of polymer-based cushioning materials with the increasing number of drops. The position of the belly of the cushion curve of MLCS tends to shift upward to the left with increasing drop height, and the belly portion became narrower. However, depending on material thickness, under identical conditions, the cushion curve of MLCS showed an opposite tendency. Conclusions: The results of this study can be useful for environment-friendly and optimal packaging design as shock and vibrations are the key factors in cushioning packaging design.

• 분석과학
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• 제8권1호
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• pp.69-77
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• 1995

원자흡수용 gas-jet assisted RF 글로우 방전시스템을 제작하고 시료손실량과 원자흡광도에 미치는 실험변수들에 관한 연구를 수행하였다. 시료손실량과 흡광도는 방전전력, 압력 및 가스흐름에 큰 영향을 받았다. 원자흡광도와 시료손실량을 가스흐름이 600ml/min로 증가할 때 까지 계속 증가하였으며, 방전 압력은 3mbar에서 최대 흡광도를 나타내었다. 방전전력이 증가할수록 시료손실량과 흡광도는 증가하였으나 시스템의 안정도에 영향을 미치는 관계로 적당한 값의 선택이 필요하였다. 스테인리스 스틸 시료 중의 Ni과 황동시료 중의 Cr의 검량선을 작성한 결과 양호한 직선성이 얻어졌다.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1084-1091
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• 2005

The indoor noise limit for road traffic noises is needed to secure comfortable acoustical quality in apartment houses. To achieve this goal, psycho-acoustic experiments were carried out with road traffic noise sources modulated by the transmission loss characteristics of the external windows. Finally, a correlation analysis between noise rating index and subjective responses, and an analysis of satisfactory percentage of the dose-response curves varied with respondents was conducted. As a result of this study, followings are suggested. (1) On correlation between dose level and psycho-acoustical response, the initial level of negative feeling is located on $40.1\~40.6\;L_{eq}$ dB(A), (2) On the degree of satisfaction to road traffic noise. near $35\;\%$ point being same dissatisfaction degree is to be assumed $40\~41$ dB(A) of indoor noise level presented into three vocabulary. It is suggested to be reasonable level of 40 dB(A) on the indoor noise limits for intruding road traffic noise. and it is appropriate to be the 5 dB level difference between grades. The results of this study may be used to evaluate the acoustic threshold level for road traffic noise or as a basis for specifying the desired acoustic environment of dwellings.

• 분석과학
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• 제5권2호
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• pp.169-176
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• 1992

금속시료의 미량원소를 분석하기 위하여 jet형과 글로우방전 이온원을 제작하여 질량 분석기와 연결시킨 후 상대이온세기와 검출한계를 측정하였다. Jet형 이온원으로 구리시료의 시료 손실속도를 측정하였을 때 가스흐름속도가 0.01L/min이었을 때 0.23 mg/min이고 가스흐름이 없을 때는 0.11 mg/min이었다. 그러나 구리의 이온세기를 측정하였을 때는 두 이온원에서 큰 차이가 없었다. 여섯 개의 동합금시료의 검정곡선으로부터 구한 각 원소의 상대이온세기는 철의 0.57부터 크롬의 3.5 범위였다. Jet형 이온원으로 4mA, 1000V 방전시 순수 구리시료의 각 원소에 대한 검출한계는 0.9 ppm에서 2 ppm 수준으로 나타났다.

• 한국자기학회지
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• 제20권6호
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• pp.228-233
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• 2010

본 연구에서는 비정질 CoFeHfO 박막 재료의 두께 변화에 따른 고주파 손실 특성을 분석하기 위하여 57~1368 nm 두께의 CoFeHfO 박막 재료에 대해 마이크로파 투자율 특성을 분석하였다. 두께가 405 nm이하에서 허수부 투자율은 2.95 GHz에서 하나의 공진주파수를 보이지만, 405 nm 이상에서는 2.97 GHz와 547 MHz에서 두 개의 공진주파수를 보인다. 저자장하에서 측정한 토오크 곡선 결과로부터 547 MHz에서 발생되는 공진주파수는 CoFeHfO 재료의 자화 용이축들의 각도 분포에 기인하는 것으로 자기장의 세기에 따라서 급격하게 감소하는 특성을 보인다. 따라서 두께가 400 nm 이상의 CoFeHfO 박막 재료를 2 GHz 대역에서 작동하는 초소형 마이크로파 부품에 적용하기 위해서는 자화 용이축의 분포각도를 최소화시켜야 한다.

• Nuclear Engineering and Technology
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• 제23권4호
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• pp.456-464
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• 1991

국산벤토나이트의 완충기능에 대한 열적 효과를 고찰하기 위하여 동해 A 시료의 X-선 회절 양상, TG/DSC 곡선, 팽윤도 및 분배계수를 각 온도에 따라 분석하였다. X-선 회절 분석결과 약 20$0^{\circ}C$의 온도에서 몬모릴로나이트의 특성 피크인 (001)이 완전히 붕괴되는 양상을 나타냈으며 DSC 곡선상에서 동해 A 시료가 Ca-벤토나이트임을 확인하였다. 시료의 팽윤도와 양이온 교환능은 약 l0$0^{\circ}C$ 정도에서 감소하기 시작하였다. Am-241, Co-60및 Cs-137등의 핵종에 대한 분배계수는 온도변화에 따라 큰 변화를 보이지는 않았으나 Sr-85의 경우는 약 15$0^{\circ}C$에서 감소하는 경향을 나타내었다. 지금까지 얻어진 데이타만을 놓고 볼때, 10$0^{\circ}C$ 이하의 온도에서는 동해 A가 완충재로서 사용될 수 있을 것으로 평가되었다.

• Corrosion Science and Technology
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• 제16권4호
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• pp.175-182
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• 2017

Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers (the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance $R_{ct}$ of the steel surface decreased and the $Fe^{3+}/Fe^{2+}$ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in $R_{ct}$ and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.

• 한국광물학회지
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• 제11권2호
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• pp.85-96
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• 1998

The sericite ore is formed by the hydrothermal alteration of rhyodacitic welded tuff. The alteration zone of the host rock can be classified into four types based on the mineral assemblages ; sericite, quartz-sericite, silicified and propylite zone. The sericite ore mainly occurs as vein types and fault clay along the fault plane in the quartz-sericite zone. Mineral components of the sericite ore are mainly sericite with minor diaspore, corundum and pyrite. The sericitic porcelaineous ore is mainly composed of quartz and sericite. Accessory minerals are muscovite, diaspore, sphene, corundum, pyrite, iron-oxides and etc. The chemical compositions of K2O, Al2O3, and ignition loss in the sericite ore increase largely than that of the host rock, while the compositions of SiO2, Na2O and Fe2O3 decrease. XRD patterns of the heat-treated sericite ores show the formation of mullite at $1,200^{\circ}C$. and the diaspore-bearing sericite ore forms mullite and corundum at $1,200^{\circ}C$. The differential thermal analysis of the sericite ores show small endothermic peak at 645~668$^{\circ}C$. and the diaspore-bearing sericite ore shows a strong endothermic peak at $517^{\circ}C$. It indicates that the decomposition of diaspore appear at lower temperature than that of sericite. The thermal expansivity of the sericite ores show the similar pattern. The sericite ores show the thermal expansivity of 3.3~4.7% at 900$^{\circ}C$ and 0.39~0.75% at 1,20$0^{\circ}C$, respectively. DTA-TG curves of the sericite ores show closely relations with the thermal expansivity.

• 한국산림과학회지
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• 제72권1호
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• pp.37-44
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• 1986

물참나무엽(葉)과 상수리나무엽(葉)의 수분특성인자(水分特性因子)의 계절변화(季節變化)를 p-v곡선법(曲線法)에 의해 측정(測定)하였다. 양수종(兩樹種)의 최대포수시(最大飽水時)의 침투압(浸透壓) ${\pi}_o$와 초기원형질(初期原形質) 분이점(分離點)의 침투압(浸透壓) ${\pi}_p$는 생육초기(生育初期)에 높고 성숙엽(成熟葉)이 되어 가면서 감소(減少)하였다. 전생육기간(全生育期間)을 통해 양수종(兩樹種)은 전수분량(全水分量)의 약(約) 10~20%의 수분(水分)을 상실(喪失)할 때 팽압(膨壓)이 0에 달(達)했다. 양수종(兩樹種)의 최대포수시(最大飽水時)의 유포(釉胞)의 탄성계수(彈性係數), Emax는 엽(葉)이 신장(伸長)함에 따라 증가(增加)하였으며, 경엽화(硬葉化)된 이후(以後)는 감소(減少)하였다. 오스몰수, Ns/DW의 위절변화(委節變化)는 물참나무엽(葉)이 상수리나무엽(葉)보다 컸으며, 상대함수율(相對含水率)(Vp/Vo, $RWC^*$, Vo/Vt)은 비교적 위절변화(委節變化)가 작았다.