• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1572-1582
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• 2003

Hybrid rocket combustion has a manifestation of stable response to the perturbations compared to solid propellant combustion. Recently, it has revealed that the low frequency combustion instability about 10 Hz was occurred mainly due to thermal inertia of solid fuel. In this paper, the combustion response function was theoretically derived by use of ZN (Zeldovich-Novozhilov) method. The result with HTPB/LOX combination showed a quite good agreement in response function with previous works and could predict the low frequency oscillations with a peak around 10 Hz which was observed experimentally. Also, it was found that the amplification region in the frequency domain is independent of the regression rate exponent n but showed the dependence of activation energy. Moreover, the response function has shown that the hybrid combustion system was stable due to negative heat release of solid fuel for vaporization, even though the addition of energetic ingredients such as AP and Al could lead to increase heat release at the fuel surface.

• 호남수학학술지
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• 제31권4호
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• pp.505-513
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• 2009

Let {$X_k;k{\in}N^d$} be centered and identically distributed random field which is asymptotically negative dependent in a certain case. In this note we prove that for $p{\alpha}$ > 1 and ${\alpha}$ > ${\frac{1}{2}}$ $E{\mid}X_1{\mid}^p(log^+{\mid}X_1{\mid}^{d-1})$ < ${\infty}$ if and only if ${\sum}_n{\mid}n{\mid}^{p{\alpha}-2}P$($max_{1{\leq}k{\leq}n{\mid}S_k{\mid}}$ > ${\epsilon}{\mid}n{\mid}$) < ${\infty}$ for all ${\epsilon}$ > 0, where log$^+$x = max{1,log x}.

• 유통과학연구
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• 제16권3호
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• pp.59-68
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• 2018

Purpose - This study empirically examines the effects of environmental dynamics(dynamics of one's own company, dynamics of competitors, and dynamics of customers), within the franchise industry, on the dependence and conflict(dysfunctional conflict and functional conflicts) and the business performances(financial and non-financial). Furthermore, we empirically examined the effects of the dependence of franchise on the conflicts(dysfunctional conflict and functional conflict) and business performances(financial and non-financial). Finally, we empirically examined the effects of the conflicts of franchise (dysfunctional conflict and functional conflict) on the business performances(financial and non-financial). Research design, data, and methodology - Our study conducted a survey on the managers and owners of the franchises located in Seoul, Gyeonggi, and Incheon. The total number of valid samples was 230, and the structural equation model was analyzed by using AMOS program. Results - First, the environmental dynamics(dynamics of one's own company, dynamics of competitors, and dynamics of customers) in the franchise industry were shown to have statistically significant positive effect on the dependence of franchise. Second, among the environmental dynamics in the franchise industry, the dynamics of one's own company and the dynamics of the customers were shown to have a statistically significant positive effect on the dysfunctional conflicts of franchisees. However, in the franchise industry, the dynamics of competitors did not have a statistically significant effect on the dysfunctional conflict of the franchise. Third, in the franchise industry, the environmental dynamics(dynamics of one's own company, dynamics of competitors, and dynamics of customers) did not have a statistically significant effect on the functional conflicts of the franchises. Fourth, the dependence of franchise was shown to have a statistically significant positive effect on the conflicts(dysfunctional conflict and functional conflict). Fifth, the dysfunctional conflict of franchisees was shown to have a statistically significant negative effect on the business performances(financial and non-financial). Sixth, the functional conflicts of franchises was shown to have a statistically significant positive effect on business performances(financial and non-financial). Conclusions - From the franchise industry researches, the environmental dynamics were selected as the preceding factors and the relationship leading to dependence, conflict, and business performance were constructed into model.

• 경제분석
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• 제27권1호
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• pp.67-90
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• 2021

본 연구는 투자자의 거래행태를 민감하게 반영하는 비트코인(BTC) 시장 자료를 이용한 실증분석을 통해 COVID-19 팬데믹이 발생하기 전과 후에 변동성과 거래량의 비선형 관계가 바뀌었다는 흥미로운 사실을 발견하였다. 즉, COVID-19 팬데믹 이전의 안정적 시장 상태에서는 정보 유입 패러다임에 근거한 이론처럼 두 변수의 관계가 양(+)으로 나타났지만 COVID-19 팬데믹 기간에 발생한 극단적 시장 스트레스 상태에서는 두 변수의 의존관계 구조가 달라지고 심지어 음(-)의 관계가 나타났다. 이는 행태경제학적 관점에서 COVID-19 팬데믹 기간의 시장 스트레스 증가가 투자자의 거래 행태(behavior)를 변화시켜 자산시장에 구조변화를 일으켰으며, 변동성과 거래량의 비선형 의존관계(특히, 극단적 분위수(quantiles)의 의존성)에 중대한 영향을 미친 결과라고 추론해 볼 수 있다. 따라서 정보 유입 외에 시장 스트레스로 인한 행태적 편의나 군집행동(herding)과 같은 심리현상이 두 변수의 의존관계 구조를 변화시키는 주요인이 될 수 있다는 전제하에 이를 검정해보았다. 본 연구는 실증분석을 위해 Ross (2015)의 구조변화 탐지 검정을 수행하였으며, 독립적이고 동일하게 분포하는(i.i.d.) 임의변수 가정 없이 비선형 관계구조와 분포 꼬리 부분의 비대칭적 의존관계를 면밀히 파악할 수 있는 Copula 회귀분위수(CRQ) 접근법을 제안하였다.

• 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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.47-47
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• 1999

2.45 GHz 마이크로웨이브를 이용하는 electron cyclotron resonance plasma enhanced chemical vapor deposition(ECR-PECVD)방법으로 다이아몬드성 탄소박막(diamond-like carbon, DLC)을 증착하였다. DLC 박막의 산업 응용을 위해서는 높은 경도와 밀착력이 필요하다. 그래서 본 실험에서는 DLC 박막의 산업 응용을 위하여 ECR-PECVD 방법으로 증착된 DLC 박막의 분석결과로부터 DLC 박막의 물성과 증착조건의 관계를 조사하였다. 기판으로는 실리콘 웨이퍼와 실험용 SUS 판을 사용하였다. 아르곤 가스를 주입하여 ECR 마이크로 웨이브 플라즈마와 negative DC bias로 기판을 플라즈마 세척한 후, 수소와 메탄가스를 반응기체로 하여 DLC 박막을 증착하였다. 박막 증착시에 13.56MHz RF 전원 공급장치로 기판에 전원을 공급하였다. DLC 박막 증착의 변수는 반응기체의 호합율, 마이크로웨이브 파워, 프로세스 압력 및 RF 전원공급장치에서 유도되는 negative self DC bias 등이다. 이때 사용된 반응기체의 혼합율(메탄/수소)은 10~50%이고, 수소 가스 흐름율은 100sccm, 메탄은 10~50sccm이다. 마이크로웨이브의 크기는 360~900W, negative self DC bias는 -500~-10 V였다. 그리고 본 실험에서는 높은 증착율을 고려하여 프로세스 압력을 10~30mTorr까지 조절하였다. ER-PECVD 방법으로 증착된 DLC 박막은 SEM으로 단면, $\alpha$-Step으로 두께, Raman 분광계로 탄소 결합구조, FTIR 분광계로 탄소와 수소 결합구조, Micro-Hardness로 경도 그리고 Scratch Tester로 밀착력 등을 분석하였다.

• 대한화학회지
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• 제43권6호
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• pp.614-620
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• 1999

양이온 계면활성제인 Dodecylpyridinium chloride(DPC)와 Tetradecyltrimethylammonium bromide(TTAB)로 구성된 혼합계면활성제의 임계마이셀농도(CMC)와 반대이온의 결합상수(${\beta}$)를 $4^{\circ}C$에서 $36^{\circ}C$까지 전도도법으로 측정하였다. CMC와 ${\beta}$값의 온도에 따른 변화로부터 DPC/TTAB 혼합계면활성제의 마이셀화에 대한 여러 가지 열역학 함수값(${\Delta}C_p$, ${\Delta}G^o_m$, ${\Delta}H^o_m$ 및 ${\Delta}S^o_m$)을 계산하였다. ${\Delta}C_p$와 ${\Delta}G^o_m$은 측정한 온도범위 내에서 모두 음의 값을 나타내었으며, ${\Delta}S^o_m$은 모두 양의 값을 나타내었다. 한편 ${\Delta}H^o_m$은 낮은 온도에서는 양의 값을 그리고 높은 온도에서는 음의 값을 띠었다. 또한 이러한 열역학 함수값은 온도와 몰분율 조성 (${\alpha}_DPC$)에 따라 큰 변화를 보였다.

• Investigative Magnetic Resonance Imaging
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• 제21권4호
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• pp.199-209
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• 2017

Purpose: Caffeine is the most widely consumed psychostimulant. It is often adopted as a tool to modulate brain activations in fMRI studies. However, its pharmaceutical effect on task-induced deactivation has not been fully examined in fMRI. Therefore, the purpose of this study was to examine the effect of caffeine on both activation and deactivation under sustained attention. Materials and Methods: Task fMRI was acquired from 26 caffeine naive healthy volunteers before and after taking caffeine pill (200 mg). Results: Statistical analysis showed an increase in cognition-load dependent task activation but a decrease in load dependent de-activation after caffeine ingestion. Increase of attention and memory task activation and its load-dependence suggest a beneficial effect of caffeine on the brain even though it has no overt behavior improvement. The reduction of deactivation by caffeine and its load-dependence indicate reduced facilitation from task-negative networks. Conclusion: Caffeine affects brain activity in a load-dependent manner accompanied by a disassociation between task-positive network and task-negative network.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권6호
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• pp.581-588
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• 2013

This paper presents a study of the process temperature dependence of $Al_2O_3$ film grown by thermal atomic layer deposition (ALD) as a passivation layer in the crystalline Si (c-Si) solar cells. The deposition rate of $Al_2O_3$ film maintained almost the same until $250^{\circ}C$, but decreased from $300^{\circ}C$. $Al_2O_3$ film deposited at $250^{\circ}C$ was found to have the highest negative fixed oxide charge density ($Q_f$) due to its O-rich condition and low hydroxyl group (-OH) density. After post-metallization annealing (PMA), $Al_2O_3$ film deposited at $250^{\circ}C$ had the lowest slow and fast interface trap density. Actually, $Al_2O_3$ film deposited at $250^{\circ}C$ showed the best passivation effects, that is, the highest excess carrier lifetime (${\tau}_{PCD}$) and lowest surface recombination velocity ($S_{eff}$) than other conditions. Therefore, $Al_2O_3$ film deposited at $250^{\circ}C$ exhibited excellent chemical and field-effect passivation properties for p-type c-Si solar cells.

• 대한두개안면성형외과학회지
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• 제14권1호
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• pp.36-40
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• 2013

Background: Correction of unilateral blepharoptosis is unexpectedly difficult because healthy eye is often affected by Hering's law. Methods: We measured changes of marginal reflex distance (MRD1) on the unaffected eyelids between preoperative and 3-month postoperative photographs after ptosis correction. This study analyzed 134 unilateral blepharoptosis patients with ptosis correction from February 2002 to February 2011. Fifty patients among them were negative in Hering's law dependence test. From the preoperative and postoperative photographs the MRD1 of unaffected upper eyelids were measured and adjusted with the average pupil diameter of Koreans. Mean age was 34.4 and male was 30 and female was 20. Average follow-up periods were 14 months. Results: Thirteenth unaffected eyes (26%) showed decreased MRD1, and 3 patients (6%) showed decreased MRD1 value over 1.0 mm. Then 3 patients needed additional operations for correction of preoperatively unaffected but ptotic eyelids. Conclusion: There were no meaningful data statistically in the value of MRD1 in every unaffected eye of the patients and in the difference between preoperative and postoperative MRD1 of groups divided according to severity, causes, and types of operation.