• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.931-937
• /
• 2018

Sutures are used not only for wound closure but also for oriental medicine field, beauty and even for plastic surgery. Especially, it is popular in the field of cosmetic surgery. In this paper, we produced sutures using PCL and PLLA with better strength than PDO sutures, which was widely used in the past. To learn about the mechanical characteristics of the PCL and PLLA sutures, the contraction change, tensile strength, and elongation were measured. And SEM was also analyzed for diameter and surface. The contraction change Ratio of sutures are stabilized after a certain period of time regardless of temperature. Also, it can be seen that the higher the temperature, the higher the contraction increase rate. And the rate change of mechanical properties is different according to the temperature before and after the glass temperature. Also the higher the temperature, the faster the molecular motion and the lower the tensile strength. The diameter of the PLLA and PCL sutures is opposite to the contraction change ratio. And it is considered that the sterilization temperature of PLLA sutures is best to set at $45^{\circ}C$ and the sterilization temperature of PCL sutures is best to set at $35^{\circ}C$.

• Information Systems Review
• /
• v.20 no.1
• /
• pp.137-158
• /
• 2018

Online platforms recently expanded their connectivity through an authing service. The growth of authing services enabled consumers to enjoy easy log in access without exerting extra effort. However, multiple points of access increases the security vulnerability of platform ecosystems. Despite the importance of balancing authing service and security, only a few studies examined platform connectivity. This study examines the optimal level of authing service of a platform and how authing strategies impact participants in a platform ecosystem. We used a game-theoretic approach to analyze security problems associated with authing services provided by online platforms for consumers and other linked platforms. The main findings are as follows: 1) the decreased expected loss of consumers will increase the number of players who participate in the platform; 2) linked platforms offer strong benefits from consumers involved in an authing service; 3) the main platform will increase its effort level, which includes security cost and checking of linked platform's security if the expected loss of the consumers is low. Our study contributes to the literature on the relationship between technology convenience and security risk and provides guidelines on authing strategies to platform managers.

• Korean Journal of Environmental Agriculture
• /
• v.4 no.1
• /
• pp.25-30
• /
• 1985

In order to characterize relationship between accumulation of cadmium, zinc and lead in soil and soil chemical properties and also to choose a suitable soil extractant for the prediction model of heavy metal content in brown rice, four extractants-0.1 M HCl, 0.1 M $HNO_3$, 0.1 M $NH_4-oxalate$ and 0.001 M 2Na-EDTA, were compared by analyzing 84 soil samples collected from paddy fields adjacent to five zinc-minig sites. Contents of Cd, and Pb in soil increased with Zn content and those of three elements were found to be much higher in surface soil ($0{\sim}15 cm$) than suvsqrface soil ($15{\sim}30 cm$). Contents of these elements in soil were positively correlated with soil pH, but its correlation between extractable heavy metal content and organic matter or CEC varied from region to region. These three elements were negatively correlated with Mg content of soils. The extractability of the metals was in the order 0.1 M $HCI{\geq}0.1 M$ $HNO_3>0.001 M$ 2Na-EDTA>0.1 M $NH_4-oxalate$.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11b
• /
• pp.751-754
• /
• 2010

본 연구는 초등학교 5, 6학년 학생들을 대상으로 인터넷 게임중독과 자아통제, 충동성과의 관계를 파악하여 올바른 인터넷 사용 문화를 장려하고, 과도한 인터넷 사용 방지교육을 위한 기초자료를 제공하고자 시도되었다. 자료는 2009년 11월 9일에서 11월 30일까지 익산시내 3개 초등학교를 임의로 선정하여 5, 6학년 학생 927명을 대상으로 조사하였다. 자료 분석은 SPSS WIN(12.0 한글판) 프로그램을 이용하여 카이제곱검정, t-검정, 일원배치 분산분석, 다중회귀분석의 통계적 방법을 이용하였다. 본 연구의 결과로는 대상자의 인터넷 게임중독 정도는 '정상' 483명(54.3%), '중독초기' 363명(40.8%), '중독중증' 43명(4.8%)으로 나타났다. 일반적 특성에 따른 인터넷 게임중독 정도를 분석한 결과 성별(p<0.01)이 유의한 차이가 있었으며 컴퓨터 사용 특성에 따른 인터넷 게임중독 정도는 이용장소(p<0.05), 주요활동(p<0.01), 평일 이용시간(p<0.01), 주말 이용시간(p<0.01)이 유의한 차이가 있었다. 또한, 인터넷 게임중독과 자아통제와의 관계를 분석한 결과 인터넷 게임중독 경향이 높을수록 자아통제 점수가 낮으며, 자아통제 점수가 높을수록 인터넷 게임중독 경향이 낮은 것으로 조사되었으며(p<0.01) 인터넷 게임중독과 충동성과의 관계를 분석한 결과 인터넷 게임중독 경향이 높을수록 충동성 점수가 높은 것으로 조사 되었는데, 이는 충동성 점수가 낮을수록 인터넷 게임중독 경향이 낮음을 의미한다(p<0.01). 자아통제와 충동성과의 관계를 분석한 결과 자아통제가 낮을수록 충동성이 높으며, 자아통제가 높을수록 충동성이 낮은 것으로 나타나서 자아통제와 충동성은 서로 반대 개념인 것을 알 수 있었으며(p<0.01) 인터넷 게임중독과 자아통제, 충동성과의 다중회귀분석 결과 유의한 영향을 주는 변수는 성별(p<0.01), 학교성적(p<0.01), 주요활동(p<0.01), 평일 이용시간(p<0.01), 주말 이용시간(p<0.01), 자아통제(p<0.01), 충동성(p<0.01)이었다. 여학생보다 남학생이, 학교성적이 높을수록, 주요활동이 비학습관련인 경우, 평일 이용시간이 1시간이상 이용할수록, 주말 이용시간이 2시간이상 많이 이용할수록, 자아통제가 낮을수록, 충동성이 높을수록, 인터넷 게임중독 경향이 높은 것으로 나타났다. 이상의 결과를 종합해 보면, 인터넷 게임중독 경향이 높을수록 자아통제 정도가 낮게, 충동성 정도는 높게 나타나고, 인터넷 게임중독 경향이 낮을수록 자아통제 정도가 높게, 충동성 정도는 낮게 나타나는 것을 알 수 있다. 또한 자아통제와 충동성은 상반된 개념으로 자아통제 정도가 높을수록 충동성은 낮아지고 자아통제 정도가 낮을수록 충동성이 높아짐을 알 수 있다.

• The Korean Journal of Applied Statistics
• /
• v.25 no.1
• /
• pp.89-99
• /
• 2012

This study investigates the Granger-causality between economic growth and demand for electricity in Korea, using two quarterly time-series data (real GDP and electricity consumption) for 1970:Q1 through 2009:Q4. We apply Hsiao's sequential procedure to identify a vector autoregressive model to a decision of the optimal lags in the vector error-correction model because the two time-series data contain unit roots respectively and they are cointegrated. According to the empirical results in this study, we find that Hsiao's approach to the Granger-causality indicates a bidirectional causal relation between economic growth and demand for electricity in Korea. Following the Granger and Engle's approach, we also find the statistical evidence on (1) short-run bidirectional causality between real GDP and electricity consumption, (2) bidirectional strong causality between them, and (3) long-run unidirectional causality running from demand for electricity to economic growth. Our results show an inconsistency with the existing studies on Korea's case; however, the results appear to provide more meaningful policy implications for the Korean economy and its strategy of sustainable growth.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.253-253
• /
• 2019

유사의 이동은 하천, 해안 지역과 같은 수계에서 하상의 변동, 침식과 퇴적을 일으켜 지형적인 변화를 초래한다. 유사의 이동은 유사의 특성과 유체의 유수동역학적 특성에 의해 결정되며 유체특성 간의 복잡한 상호 작용에 의해 변화한다. 유사가 가지는 점착성은 유사의 특성에 큰 영향을 끼친다. 입자의 크기가 매우 작은 점착성 유사는 그 표면이 가지는 전자기적 점착력에 의해 주위의 1차 입자나 다른 작은 알갱이들이 서로 뭉치는 응집과 충돌에 의해 크기가 작아지는 파괴의 과정을 겪는다. 이 과정을 응집현상이라고 하며 응집현상을 통해 점착성 유사의 크기와 밀도, 침강속도는 계속해서 변화한다. 따라서 점착성 유사의 응집거동 고려한 유사 이동 연구는 필수적이다. 과거 연구의 많은 사례에서 유사의 크기와 농도는 비례 관계를 가지는 것이 일반적이라 알려져 있다. 그러나 실제 현장에서 측정한 결과 유사의 크기와 농도가 반비례 관계를 가지는 특이점이 발견되었다. 실측 연구에서 발견된 응집거동에 따른 유사의 특성의 특이한 변화를 설명하기 위해 1차원 연직 수치 모형(1DV)을 이용하여 수치 실험을 수행하였다. 모의 수행 시, 흐름 조건을 크기와 방향이 일정한 순방향흐름(Current)에 특정 주기와 진폭을 가지는 진동 흐름(Oscillatory Flow)을 추가하여 진행하였다. 플럭의 성장과 그에 따른 입자의 크기는 많은 현상에 영향을 받는다. 그 중 응집현상의 응집 과정과 파괴 과정 중 어떤 현상이 더 우세한지 그 경쟁관계를 파악하여 플럭의 크기의 증감을 예측할 수 있게 농도(?)와 난류소산매개변수(?)를 이용하여 $c/G^{0.5}$로 매개화하였다. 실험 결과, 순방향 흐름을 제외하고 스토크스파 흐름 조건을 이용하여 진행된 모의에서는 플럭의 크기와 농도가 반비례하는 현상을 관찰할 수 없었으며 $c/G^{0.5}$ 의 변화 역시 흐름의 속도와 농도가 더 큰 지점에서 큰 값을 가지는 일반적인 결과를 나타내었다. 그러나 같은 조건에서 순방향흐름을 추가하여 모의한 결과에서는 플럭의 크기와 농도가 반비례하는 현상을 나타냈다. 연직 방향 $c/G^{0.5}$의 변화를 나타낸 그래프에서 응집과 파괴의 우세에 따라 $c/G^{0.5}$ 가 역전되는 현상을 확인하였다. 즉, 플럭의 크기는 난류의 구조와 그 영향에 의해 농도와 비례관계를 갖지 않을 수도 있다고 판단된다. 또한 본 연구에서 정상류 흐름 조건의 유무에 따라 플럭의 크기와 농도가 비례하거나 반비례하는 상반된 결과를 보였다. 정상류 흐름 조건이 난류의 강도에 큰 역할을 하며 이에 따라 비선형 관계에 영향을 끼친다는 것을 발견하였다. 그러나 흐름의 영향에 대한 더 자세한 분석은 본 연구에서 진행되지 않았으며 향후 연구 시에 분명히 고려되어야 할 사항이다.

• Journal of Korea Society of Industrial Information Systems
• /
• v.25 no.6
• /
• pp.171-192
• /
• 2020

The purpose of this study is, first, to empirically verify the relationship between the influences of the start-up performance and the inherent fear factor of failure on the start-up performance through the preparation of the start-up. Second, this study aims to prove the influence of the moderating effect of social support on the relationship between start-up preparation and the burden of start-up failure. The research subjects were sampled and analyzed by 298 start-ups who are currently starting their own businesses. This study founds that preparation of start-up items, which is a subordinate theory of start-up preparation, had a significant effect on start-up performance, and that anxiety about failure had a significant effect on start-up performance. Using the SPSS statistical program, the hierarchical regression analysis proved the moderating effect of social support in the relationship between star-tup preparation, start-up failure burden and startup performance. Furthermore, the moderating effect of social support among start-up preparation, start-up failure burden and start-up achievement was analyzed, but no significant results were found for start-up failure burden. Besides, the effect of the opposite concept of independent variables on the dependent variables at the same time is to be analysed.

• Economic Analysis
• /
• v.26 no.2
• /
• pp.72-113
• /
• 2020

This study investigates the relationship between mineral exports to China, North Korea's most important source of foreign currency acquisition, and its imports of various items from China from the first quarter of 1995 through to the third quarter of 2019. The results from a cointegration analysis suggest that there exists a long-run equilibrium relationship between mineral exports and imports of food, fuel, and some intermediate goods, such as industrial supplies, parts, and accessories. The results from a vector autoregression using first-differenced variables indicate that the short-run relationship between mineral exports and imports is different between the period before and after the third quarter of 2010. Prior to structural changes, i.e., before the third quarter of 2010, import shocks affected mineral exports. However, after the third quarter of 2010, an increase in mineral exports led to an increase in the import of vehicles, intermediate goods, and luxury goods. This paper shows both the possibilities and the limits that mineral exports can contribute to North Korea's economic growth. The results, which show that mineral exports have a long-run relationship with intermediate goods, such as industrial supplies, parts and accessories, imply that mineral exports to China could have a positive effect on the North Korean economy. However, the fact that mineral exports do not have any significant effect on the import of machinery and equipment, which helps the accumulation of capital formation, shows that mineral exports have a limited effect on inducing long-term growth in the North Korean economy.

• Information Systems Review
• /
• v.16 no.2
• /
• pp.77-95
• /
• 2014

From the success of TDX and CDMA to today's social media boom, Korea's ICT has achieved an amazing growth for the last couple of decades. However, in spite of ICT's role as an engine of growth in Korea, there have been concerns that ICT growth would negatively affect national employment due to the labor substitution effect. While some scholars insist that ICT would positively affect employment because it will enlarge the size of industry itself, many people blame ICT as a main culprit of rising unemployment rates. In this study, we try to empirically find the true effect of ICT growth on employment in Korea. We use the data of ICT productions, ICT investments, and various industries employments from 1995 to 2011. The methodologies we adopted for this study is Granger causality tests and impulse response functions based on vector autoregression (VAR) model. We find that ICT has negative impact on service industries, while it has positive impact on manufacturing industries. Meanwhile, ICT has no statistically significant impact on ICT industry itself. Since the impacts of ICT on employment are mixed, we can argue that ICT should not be blamed for the main cause of low employment. We suggest a direction of future policies to utilize ICT for vitalizing employments in Korea.

• International Area Studies Review
• /
• v.14 no.1
• /
• pp.99-119
• /
• 2010

This study explores the natural gas market and the oil market in the U.S. and the European oil market. It focuses on two kinds of analyses; one is to confirm whether there is the predictive power between spot and futures within homogeneous commodity market(or inter-heterogeneous commodity market) through Granger-causality test in terms of the return rate and the volatility. The other is to examine the spot price stabilizing effect of futures price through regression analysis. When it comes to the predictive power of inter-commodity market, there was a conflicting aspect between the return rate of spot and futures. Overall, however, its statistical significance was low. With respect to the volatility, we found that the natural gas market has little influence on the oil market unlike the predictive power of oil market on natural gas market. Concerning the return rate of the predictive power within homogeneous commodity market, we found that the return rate of spot has the predictive power on futures only in the European market. In addition, we identified that there is feedback between spot and futures in the all commodity markets regarding volatility. As a result of the spot price stabilizing effect analysis of futures price, futures volatility increased the spot volatility.