• 한국가스학회지
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• 제20권2호
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• pp.16-22
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• 2016

자연발화 특성은 가연성물질의 취급 및 화재예방을 위한 중요한 인자이다. 본 연구는 ASTM D2155식 발화온도 측정장치를 사용하여 Ethylene Glycol (EG)과 Diethylene Glycol (DEG)의 자연발화 특성 및 활성화에너지를 고찰하였다. 최소자연발화온도의 경우 EG는 시료량 $75{\sim}160{\mu}{\ell}$의 범위에서 $434^{\circ}C$를 구하였고 DEG는 시료량 $130{\sim}150{\mu}{\ell}$의 범위에서 $387^{\circ}C$를 측정 하였다. 또한 시료량 $140{\mu}{\ell}$에서 순간발화온도를 측정한 결과 EG는 $579^{\circ}C$, DEG는 $569^{\circ}C$를 나타내었다. 본 연구에서 측정된 발화온도와 발화지연시간의 측정값을 Semenov 방정식으로부터 최소자승법에 의하여 활성화 에너지를 구한 결과 EG는 25.41 Kcal/mol, DEG는 14.07 Kcal/mol을 구하였으며 DEG의 최소자연발화온도, 순간발화온도 및 활성화에너지가 EG보다 낮아 자연발화의 위험성이 더 높다는 것을 확인 할 수 있었다.

• Journal of Radiation Protection and Research
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• 제45권3호
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• pp.130-141
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• 2020

Background: Concrete activation in cyclotron vaults is a major concern associated with their decommissioning because a considerable amount of activated concrete is generated by secondary neutrons during the operation of cyclotrons. Reducing the amount of activated concrete is important because of the high cost associated with radioactive waste management. This study aims to investigate the capability of the neutron absorbing materials to reduce concrete activation. Materials and Methods: The Particle and Heavy Ion Transport code System (PHITS) code was used to simulate a cyclotron target and room. The dimensions of the room were 457 cm (length), 470 cm (width), and 320 cm (height). Gd₂O₃, B₄C, polyethylene (PE), and borated (5 wt% ^natB) PE with thicknesses of 5, 10, and 15 cm and their different combinations were selected as neutron absorbing materials. They were placed on the concrete walls to determine their effects on thermal neutrons. Thin B₄C and Gd₂O₃ were placed between the concrete wall and additional PE shield separately to decrease the required thickness of the additional shield, and the thermal neutron flux at certain depths inside the concrete was calculated for each condition. Subsequently, the optimum combination was determined with respect to radioactive waste reduction, price, and availability, and the total reduced radioactive concrete waste was estimated. Results and Discussion: In the specific conditions considered in this study, the front wall with respect to the proton beam contained radioactive waste with a depth of up to 64 cm without any additional shield. A single layer of additional shield was inefficient because a thick shield was required. Two-layer combinations comprising 0.1- or 0.4-cm-thick B₄C or Gd₂O₃ behind 10 cm-thick PE were studied to verify whether the appropriate thickness of the additional shield could be maintained. The number of transmitted thermal neutrons reduced to 30% in case of 0.1 cm-thick Gd₂O₃+10 cm-thick PE or 0.1 cm-thick B₄C+10 cm-thick PE. Thus, the thickness of the radioactive waste in the front wall was reduced from 64 to 48 cm. Conclusion: Based on price and availability, the combination of the 10 cm-thick PE+0.1 cmthick B₄C was reasonable and could effectively reduce the number of thermal neutrons. The amount of radioactive concrete waste was reduced by factor of two when considering whole concrete walls of the PET cyclotron vault.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1707-1714
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• 2015

본 연구는 사건관련 fMRI를 이용하여 언어 내 및 언어 간 그림명명 과제를 수행하는 동안 모국어와 외래어 명사관련 피질 활성화 영역을 비교해 보고, 특히 외래어의 활성화 패턴이 모국어에 동조되는지를 알아보았다. 아울러 과제수행 언어가 정해지지 않은 임의적 언어전환 조건에 관여하는 활성화 영역도 연구대상이었다. 실험결과, 한 가지 수행언어만으로 제한되는 과제에서는 모국어 및 외래어 모두 좌측 하전두회(LIFG) 활성화가 일어났으나 모국어의 활성화 정도가 더 컸으며, 특히 외래어 명명 시 모국어와의 활성화 강도는 약화된 반면 영역분포는 유사한 결과를 얻었다. 이는 외래어가, 외국어가 아닌 모국어에 동조되었음을 시사한다 하겠다. 마지막으로 언어전환 조건에서의 실험에서는 좌측 하전두피질 외에 우측 중전두피 질이 관여함을 발견함으로써 실험수준이 아닌 일상수준의 다언어 사용에 있어, 의식이전의 언어 간 부호전환에 관여하는 우반구의 상대적인 기여와 역할을 시사하는 결과를 얻었다.

• Carbon letters
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• 제4권4호
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• pp.168-174
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• 2003

Silver nitrate ($AgNO_3$) powder was mixed into a reformed pitch precursor. Then, the silver-containing pitch was melt spun to form round and "C" shape fibers. A wire mesh was inserted prior to the nozzle to improve the spinnability of the silvercontaining precursor pitch. Silver particles in the carbon fibers (CFs) were detected by XRD and TEM. These tests showed that silver particles were uniformly distributed and the total amount of silver remained constant during stabilization and carbonization. Next, the silver-containing CFs were activated by steam diluted in nitrogen gas. Silver particles accelerated the activation rate, but the specific surface areas of the silver-containing ACFs were similar to those of non-silver containing ACFs at the same burn-off levels. The specific surface area of the C-shaped activated carbon fibers was larger than that of the round activated carbon fibers. The likely reason is that the surface area of a C-shaped CF is about two times larger than that of a round CF when equivalent cross-sectional areas are compared. A small amount of silver particles in the periphery of the CFs was removed during the activation, but the remainder of silver was stayed within the ACFs.

• 공업화학
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• 제9권3호
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• pp.419-423
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• 1998

본 연구에서는 인도네시아산 석탄을 원료로 수증기 활성화 방법으로 Rotary Kiln을 탄화 및 부활로로 이용하여 활성탄을 제조하였으며, 활성화 온도 $900^{\circ}C$에서 탄화온도와 반응수증기량이 활성탄의 특성에 미치는 영향을 조사하였다. 최적의 조업조건은 탄화온도 $700^{\circ}C$, 활성화온도 $900^{\circ}C$에서 총수증기 주입량이 2.7g steam/g char인 경우였으며, 이 조건하에서 제조된 활성탄은 경도 97, 충진밀도 0.48, 요오드흡착력 1,010mg/g, M.B. 흡착력 230mg/g, B.E.T. $1,020m^2/g$의 특성을 나타내었다.

• 한국수소및신에너지학회논문집
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• 제8권4호
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• pp.181-185
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• 1997

The electrochemical properties of the $AB_2$-type (Zr-Ti-V-Ni-Cr-Co-Mn) metal hydride electrodes prepared by ball milling with $AB_5-type\{(LM)Ni_{3.6}Al_{0.4}Co_{0.7}Mn_{0.3}\}$(LM : Lanthanum-rich mischmetal) alloy powder as a surface activator were investigated. By ball milling with $AB_5$ type alloy powder, the activation of $AB_2$ type metal hydride electrode was accelerated resulting in an increase of discharge capacity from 35% to 85% of the maximum capacity at the first cycle. As the amount of surface activator increased the activation rate increased, whereas the discharge capacity increased with 10wt% and decreased with 20wt% addition of the surface activator. When the amount of the surface activator was kept constant as 10wt%, the discharge capacity and the activation rate increased with ball milling time up to 20 hours. However beyond 20 hours of ball milling time, they decreased drastically due to the nano-crystallization or amorphorzation of the alloy powder.

• Nuclear Engineering and Technology
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• 제5권2호
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• pp.137-149
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• 1973

중성자 방사화 및 방사능 계측에 관계하는 핵데타를 세밀히 연구검토하여 망간을 불순물로 함유하고 있는 철선을 단일비교체로 한 중성자 방사화분석법을 발전시켰다. 유효반응 단면적의 변화를 원자로 내부 스펙트럽의 열외 중성자의 비율과 같은 스펙트럼 지표 및 그 외 다른 변수의 함수로 검토하였으며 조사위치에서 중성자 스펙트럽의 변위로 생기는 오차를 토의하였다. 각원소의 이미 아는양을 취하여 단일비교체와 함께 조사한 다음 본법에 의해서 그 함량을 산출하여서 원래 취한 양과 비교하였다. 그 결과 우연오차는 일반적인 비교법으로 얻은 오차보다 크지 않았으나 계통적 오차는 대략 20%이내였다. 본법을 모나자이트 중에 함유된 14개 희토류 원소의 정량과 표준배추시료 중에 있는 다른 7개의 원소정량에 적용하였다. 그 결과 분석치는 만족할만한 재현성을 나타내었으며 종래의 비교법으로 얻을 수 있는 정도의 정착성으로 이들 원소를 분석할 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제5권5호
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• pp.367-371
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• 2001

The chromosome 7-linked long QT syndrome (LQT2) is caused by mutations in the human ether-a- go-go-related gene (HERG) that encodes the rapidly activating delayed rectifier $K^+$ current, $I_{Kr},$ in cardiac myocytes. Different types of mutations have been identified in various locations of HERG channel. One of the mechanisms for the loss of normal channel function is due to membrane trafficking of channel protein. The decreased channel function in some deletion mutants appears to be due to loss of coupling with wild type HERG to form the functional channel as the tetramer. Most of missense mutants with few exceptions could interact with wild type HERG to form functional tetramer and caused dominant negative suppression with co-injection with wild type HERG showing variable effects on current amplitude, voltage dependence, and kinetics of activation and inactivation. Two missense mutants at pore regions of HERG found in Japanese LQT2 (A614V and V630L) showed accentuated inward rectification due to a negative shift in steady-state inactivation and fast inactivation. One mutation in S4 region (R534C) produced a negative shift in current activation, indicating the S4 serving as the voltage sensor and accelerated deactivation. The C-terminus mutation, S818L, could not express the current by mutant alone and did not show dominant negative suppression with co-injection of equal amount of wild type cRNA. Co-injection of excess amount of mutant with wild type produced dominant negative suppression with a shift in voltage dependent activation. Therefore, multiple mechanisms are involved in different mutations and functional abnormality in LQT2. Further characterization with the interactions between various mutants in HERG and the regulatory subunits of the channels (MiRP1 and minK) is to be clarified.

• 한국전문물리치료학회지
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• 제24권1호
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• pp.61-70
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• 2017

Background: Scapular winging is a prominence of the entire scapular medial border, mainly caused by insufficient activity of the serratus anterior (SA) and imbalance of scapulothoracic muscles. Push-up plus (PUP) exercise has been commonly used to increase SA muscle activity. The facilitation of abdominal muscle may affect scapular muscle activity by myofascial connections. Thus, the sequential activation of the turnk muscles is suggested to facilitate the transition of proper force from upper limb and restore force couple of scapular muscles. The abdominal drawing-in maneuver (ADIM) has been effective in improving activation of the deep trunk muscles during movement. Objects: The aim of this study was to determine the effect of ADIM on the activity of the upper trapezius (UT), lower trapezius (LT), and SA during PUP exercises in subjects with scapular winging. Methods: Fourteen men with scapular winging (determined as a of distance between the scapular medial border and thoracic wall over 3 cm) volunteered for our study. The subjects performed the PUP exercise with and without ADIM. Surface electromyography was used to collect the electromyography data of the UT, LT, and SA. A scapulometer was used to measure the amount of scapular winging. Results: SA activity was significantly greater and scapular winging significantly lower during the PUP exercise with ADIM than during those without ADIM. Conclusion: PUP exercise with ADIM can be used as an beneficial method to improve SA activation and to reduce the amount of scapular winging in subjects with scapular winging.

• 한국전문물리치료학회지
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• 제14권3호
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• pp.72-80
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• 2007

The purpose of this study was to verify the effects on fine motor, muscle strength (hand-grip), explosive muscular strength (vertical jump) and muscular endurance (sit-up) after ingesting coffee. Hence this study targeted a sample group of 38 healthy men in their twenties, without cardiac disorders and muscle disorders and none of them were hypersensitive to caffeine with symptoms such as palpitation and dyspnea. Nineteen of them ingested coffee, whereas the other nineteen men ingested decaffeinated coffee at the same amount. The amount of coffee was controlled by weight so as to regulate intake to 6 mg caffeine per kg. Research material was evaluated through O'Conner's finger dexterity test, hand-grip strength test, vertical jump test and sit-up test. The data were analyzed by means of paired t-test and ANCOVA. The material was then, analyzed by means of two-way ANOVA in order to verify the effect of one or two cups of coffee on fine motor and hand-grip strength. All parameters were measured by an independent observer. The results were as follows: There were no significant differences to fine motor, hand-grip strength, vertical jump, sit-up before and after drinking decaffeinated coffee, but there was a difference to those before and after drinking caffeine coffee. There was no significant difference to hand dexterity and hand-grip strength in one or two cups of coffee. Intake of a certain dosage of caffeine effects activation of muscles working in a short period based on the results. As a consequence, intake of certain dosages of caffeine was beneficial to enhance efficiency of activity during exercises, but it is will be difficult to obtain the desired result with only one or two cups of coffee.