선박 복원성 평가에 관한 항해사의 경험적 인지도 분석 연구

김홍범,안영중,이윤석,정창현,공길영 해양환경안전학회 2023 해양환경안전학회지 Vol.29 No.4

The navigational officer's knowledge about securing stability, an essential factor for promoting the safe operation of ships, should be improved along with advancement in ship technology, such as the large-sized ships and the appearance of autonomous ships. Accordingly, this study conducted a survey on stability, targeting navigational officers, and analyzed empirical awareness using general characteristics. Navigational officers had a high level of understanding of the stability criteria for a higher rank, but lacked the understanding of the special criteria for specific ship types. Of the total respondents, 87.6% were using a loading computer to evaluate stability. The GM scored the highest (3.891/5.000 points) as a method of evaluating stability on the ship. Further, whether the stability was secured was determined based on the GM and stability criteria. Most navigational officers replenish additional ballast water to improve the stability and use a small angle of rudder in the case of lacking stability. The results of this study are intended to be used as important data for improving education and research on operator-centered stability in the future by evaluating the empirical awareness of navigational officers on the ship stability.

A quantitative methodology for evaluating the ship stability using the index for marine ship intact stability assessment model

임남균,최훈 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

IMO stability regulations include various stability parameters such as GM values. To assess the stability of the ships, we should check all stability parameters of the IMO requirements. However, since this process is complex, a more convenient way to evaluate stability performance is required. In this research, the index for marine ship intact stability assessment (IMSISA) model was developed to solve these problems. The IMSISA model consists of a stability index calculation module and a stability assessment module. In the stability index calculation module, ten stability parameters, including GM, were used to develop the stability index, which has the advantage of being able to quantify the ship stability. The stability assessment module uses the stability index value to determine the stability status of the ship and provides the captain with stability management guidelines. To verify the proposed model, the basic stability calculations were performed for two model ships in 32 loading situations. The proposed model was found to provide better performance in the stability assessment than the previous study. By applying the IMSISA model to the ships, the captain can assess the ship stability more quantitatively and efficiently.

The Effectiveness of External Support on Hip Abduction Strength in Subjects with Insufficient Core Stability

전인철 KEMA학회 2022 근골격계과학기술학회 Vol.6 No.2

Background The core stability is important for the performance of hip joint in the standing position. However, little research in comparison of the hip abductor strength in the standing position according to core stability has been reported. Purpose Core stability was important to manage chronic lower back pain and improve standing balance. This study investigated the influence of core stability on hip abductor strength in standing. Study design A parallel-groups design Methods 34 subjects with sufficient and insufficient core stability between 20–31 years. Hip abductor strength was measured using Smart KEMA tensiometer, with subjects between sufficient and insufficient core stability. Two groups were classified by using the double bent leg lowering test. The hip abductor strength were measured in standing with and without an external support. The two-way mixed analysis of variance was applied. Results In the group with insufficient core stability, The hip abductor strength in standing was greater with external support than the condition without external support. No significant difference was found in the hip abductor strength in the subjects with sufficient core stability between the conditions with and without external support. Conclusions The performance of the hip abductor strength can be influenced by core stability in standing. In the group with insufficient core stability, the hip abduction strength in standing is better with external support, as compared to the condition without external support. Therefore, core stability exercise can be recommended in individuals with insufficient core stability to improve the hip abductor performance in standing.

교차제도비교(cross-institutional comparison)를 통한 정부안정성 결정인자의 경험적 탐색 : 의회분절도, 대정부 항거시위 및 신뢰의 등가성 평가

김지희 한국외국어대학교 EU연구소 2009 EU연구 Vol.- No.25

Previous studies on the durability and stability of government have been limited in scope to the West European parliamentary democracies. Structural stability of government, however, is critical in securing effective governance, and furthermore, stability of political regime itself under any institutional arrangement. In this context, this paper purports to develop a number of cross-national, cross-institutional analytic models of governmental stability for delineating the measurement equivalence of the two widely-employed indicators of governmental stability: cabinet stability and outbreak of anti-government mass protest. In addition, the explanatory potential of parliamentary fractionalization and political trust on governmental stability has been measured in order to test their cross-national measurement validity. The result of statistical analysis shows that mass support in terms of electoral competitiveness and political trust are playing the pivotal role in explaining the cross-national variance in cabinet stability and outbreak of mass political protest, respectively. It was also disclosed that cabinet stability and outbreak of mass protest are significantly correlated, leading to the tentative conclusion that these two indicators are equivalent in measuring the stability of government across different regime types. Finally, it was found that parliamentary fractionalization functions as an intervening variable in the causal process of governmental stability, especially when there exists comparative higher degree of political cleavage within parliament. 정부의 지속성과 안정성에 관한 기존 연구는 거의 획일적으로 내각제를 채택하고 있는 서유럽 국가들을 대상으로 이루어졌으나, 정부의 안정성은 체제의 성격을 불문하고 가버넌스의 효율성을 확보하기 위한 핵심적 요건이기 때문에 통치구조의 안정성과 직결된다. 이에 따라 본 연구는 정부의 안정성을 체제 자체의 안정성을 측정하는 주요 지표로 간주하고, 그간 체제유형에 따라 선별적으로 채택되어 온 정부안정성 측정지표인 내각안정성(내각제)과 대정부 항거시위(대통령제)의 교차사례적 측정타당성을 확인함과 아울러, 내각안정성을 결정하는 핵심적 요인으로 판명된 의회분절도와 정치신뢰가 과연 내각제와 대통령제를 포괄하는 교차체제적 등가성을 지니고 있는가를 탐색해 보았다. 이를 위해 서유럽 14개 국가(11개 내각제ㆍ2개 준대통령제ㆍ1개 회의체제)와 여타 지역 21개 대통령제 국가 등 총 35개 국가를 대상으로 정부안정성을 결정하는 인자들을 추적하고, 그 등가성을 파악하기 위한 가설적 분석모형을 검증하였다. 검증 결과 국민적 지지기반이 정부안정의 핵심적 영향요인임을 발견하였으며, 특히 국민적 지지기반 변인 중 하나인 선거경쟁도는 내각안정성에, 또 다른 국민적 지지기반 변인인 정치신뢰는 대정부 항거시위 수준에 영향력을 행사하고 있음이 밝혀졌다. 또한 내각안정성과 대정부 항거시위는 통계적으로 유의미한 상관관계를 나타냈으며, 의회분절도는 의회가 상대적으로 더 많이 분절되어 있는 국가들의 경우 내각안정성과 독립변인들 간의 인과관계에 개입하는 변인으로서의 위상을 지니고 있음에 따라 교차체제적 등가성을 확보하고 있음이 확인되었다.

한국의 직업안정성 변화와 원인 분석

김기덕,어수봉 (사)한국직업자격학회 2019 직업과 자격 연구 Vol.8 No.3

The purpose of this study is to introduce a new methodology for measuring job stability in Korea, which is undervalued, and to reveal how job stability has changed from 2003 to 2018. In addition, this study attempts to investigate the cause of the change of job stability over the long term through the decomposition method. As Korea experienced sudden job instability such as massive layoffs and voluntary retirement through the foreign exchange crisis in the past, job seekers' preference for stable jobs gradually increased. Since then, Korea has been recognized as having a low level of job stability because of its shorter average tenure than other countries. Therefore, this paper empirically analyzes how job stability of Korea has changed from 2003 to 2018, when the impact of the foreign exchange crisis has disappeared. The analysis measured the one-year job retention rate in only those aged between 20 and 54 with Supplementary Results of the Economically Active Population Survey, which is investigated in August every year. The analysis showed that job stability continued to increase from 2003 to 2013, and has since remained in the 70 percent range. Job stability increased more than females, and by age group, the increase in age over 30, while the increase in occupational stability of young people is minimal. The increase in job stability has led to a greater increase in women than men. By age, more than 30 years of age increased, while the job stability of young people was minimal. Decomposed by human and employment characteristics to explore the causes of job stability increase, the high-education of the workforce has been identified as the biggest reason for increasing job stability. The effect of this higher education was found to have more impact on job stability of men than women. 이 연구의 목적은 저평가되고 있는 우리나라의 직업안정성을 측정하기 위한 새로운 방법론을 소개하고, 이를 통해 2003년 이후부터 2018년까지 직업안정성이 어떻게 변화해 왔는지를 밝히는 데 그 목적이 있다. 또한 장기간에 걸친 직업안정성 변화의 원인이 무엇인지를 분해기법을 통해 규명하고자 한다. 우리나라는 과거 외환위기를 겪는 과정에서 대량해고, 명예퇴직 등 급작스럽게 찾아온 고용의 불안을 경험하면서 안정된 일자리에 대한 선호가 점차 증가했다. 이후 우리나라는 다른 나라에 비해 평균 근속기간이 짧은 등의 이유로 직업안정성이 매우 낮은 국가로 인식되고 있다. 이에 본 논문에서는 외환위기의 여파가 어느 정도 사라졌다고 판단되는 2003년 이후부터 2018년까지 한국의 직업안정성이 어떻게 변화해 왔는지를 실증분석하고자 한다. 분석은 매년 8월에 조사되는 경제활동인구조사 근로형태별 부가조사 데이터로 20~54세만을 대상으로 1년 고용유지율을 측정하였다. 분석 결과 직업안정성은 2003년부터 2013년까지 지속적으로 증가했으며, 이후 70%대를 유지하고 있는 것으로 나타났다. 직업안정성 증가는 남성보다는 여성이 더 크게 증가했으며, 연령별로는 30대 이상은 증가한 반면, 청년층의 직업안정성 증가는 미미하다. 직업안정성 증가의 원인을 탐색하기 위해 인적 및 고용특성별로 분해한 결과 노동력의 고학력화가 직업안정성을 증가시키는 가장 큰 원인으로 확인되었으며, 이런 고학력화는 여성보다는 남성의 고용안정성에 더 많은 영향을 미친 것으로 확인되었다.

양이온성 계면활성제 거품 지속성 증진방법 연구

김홍열(Hong Yeol Kim),정승우(Seung Woo Jeong) 大韓環境工學會 2012 대한환경공학회지 Vol.34 No.11

계면활성제 거품(foam)을 아예 형성하지 못하거나 foam 지속도가 매우 낮은 양이온성 계면활성제의 foam 지속성을 높이는 방법에 대해 연구하였다. 음이온성 계면활성제를 보조제로 첨가하는 방법, 콜로이드를 혼합하는 방법, 수용성 수지인 폴리비닐알콜을 첨가하는 방법 등 다양한 시도를 평가하였다. 각 5% 양이온성 계면활성제 용액의 foam 지속도를 평가한 결과, Cationic starch (CA-ST)는 foam이 전혀 발생되지 않았지만, Methyl triethanol ammonium methyl sulfate distearyl ester (CEQ90)의 foam 지속시간은 평균 46초, Cetyl trimethyl ammonium chloride (CM29)는 평균 31초로서 매우 낮았다. 음이온성 계면활성제 Sodium dodecyl sulfate (SDS) 첨가는 양이온성 계면활성제의 종류에 따라 지속도가 매우 다르게 나타났다. Cationic starch (CA-ST)의 foam 지속도는 매우 크게 증가된 반면 CEQ90와 CM29는 오히려 감소되었다. 콜로이드(SiO₂, kaolin) 혼합이 양이온성 계면활성제 foam 지속도에 미치는 영향을 평가한 결과, CA-ST는 콜로이드 혼합시 foam이 전혀 발생되지 않았고, CEQ90과 CM29는 콜로이드를 주입하였을 경우 주입을 하지 않았을 때보다 지속도가 높아졌다. 수용성수지인 polyvinyl alcohol (PVA)첨가가 양이온성 계면활성제 foam 지속도에 미치는 영향을 평가한 결과, CA-ST는 PVA혼합에서도 foam이 전혀 발생 되지 않았지만, CEQ90과 CM29는 PVA의 농도가 높을수록 foam 지속도가 증가하였다. 양이온성 계면활성제에 음이온성 계면활성제 SDS와 콜로이드를 동시에 첨가한 결과 콜로이드보다 음이온성 계면활성제에 의해 양이온성 계면활성제 foam 지속도가 결정 되었다. 음이온성 계면활성제 SDS와 PVA를 동시에 첨가하여 평가한 결과 PVA보다 역시 음이온성 계면활성제에 의해 양이온성 계면활성제의 foam 지속도가 결정되었다. Foam을 전혀 형성하지 못했던 양이온성 계면활성제인 CA-ST는 음이온성 계면활성제 SDS 0.14%, PVA 2.5% 첨가 조건에서 foam 지속시간이 평균 8,780초로 획기적으로 증가하였고 타 양이온성 계면활성제 CEQ90 보다 약 8배 이상의 지속시간을 보여주었다. 본 연구결과 foam이 형성되지 않거나 지속시간이 매우 짧은 양이온성 계면활성제는 음이온성 계면활성제를 첨가할 경우 foam형성에 도움을 받을 수 있고 colloid 및 PVA 등의 보조를 통해 양이온성 계면활성제의 지속도를 혁신적으로 증가시킬 수 있는 것으로 확인되었다. 그리고 양이온 계면활성제의 foam 지속도는 음이온성 계면활성제의 첨가농도에 의해 가장 큰 영향을 받는 것으로 보인다. This study tried to find a suitable method for enhancing the foam stability of cationic surfactants that normally generate less foam or no foam. Several trials were made to enhance the foam stability: addition of anionic surfactant, colloids and polymer. Cationic starch (CA-ST) did not form foam at all, while the foam stability of two other cationic surfactant also showed low levels; methyl triethanol ammonium methyl sulfate distearyl ester (CEQ90) for 46 sec. and Cetyl trimethyl ammonium chloride (CM29) for 31 seconds. Foam stability of cationic surfactants were significantly affected by addition of anionic surfactant, sodium dodecyl sulfate (SDS). Foam stability of CA-ST was significantly enhanced by addition of SDS, while those of CEQ90 and CM29 were decreased. Addition of colloids (SiO₂, kaolin) and polyvinyl alcohol (PVA) enhanced foam stabilities of CEQ90 and CM29. However, CA-ST did not form foam even in the presence of colloids or PVA. Effect of simultaneous addition of colloids and anionic surfactant on foam stability of cationic surfactant showed that foam stability of cationic surfactant was more influenced by addition of anionic surfactant than colloids. Effect of simultaneous addition of PVA and anionic surfactant on the foam stability of cationic surfactant also showed that presence of anionic surfactant significantly affect the foam stability of cationic surfactant. Foam stability of CA-ST was greatly increased to 8,780 seconds by addition of SDS 0.14% and PVA 2.5%. The foam stability of CA-ST was 8 times higher than CEQ 90. This study suggested that cationic surfactants not forming foam can generate foam by addition of anionic surfactant and its stability can be additionally increased by addition of colloids and PVA. The study results showed that enhancement in foam stability of cationic surfactant was prominently affected by the concentration of anionic surfactant added.

선박 운항자 지원 시스템용 선박 복원성능 지수 개발

임남균,황수진,최훈 해양환경안전학회 2018 해양환경안전학회지 Vol.24 No.1

All ships should ensure stability in accordance with IMO regulations. However, GM is only used to determine ship stability because it takes a lot of time to validate all regulations. This is a problem given that the safety of vessels cannot be guaranteed, potentially leading to accidents. There is a need for a more intuitive and comprehensive method of confirming the stability of ships. This study developed a stability index that expresses ship stability in one value. An index equation is defined based on the 6 stability criteria for ships prescribed by IMO and the result of calculating the ship stability of a model ship. A stability index has been derived for each loading condition by applying the index equation to the same ship. It can clearly be seen that this stability index appropriately explains the criteria. In other words, it is possible to assess ship stability with one value and confirm whether the ship stability satisfies IMO regulations. This index will help masters and officers more easily and accurately check ship stability. 선박의 안전 확보를 위해 준수해야 하는 IMO 복원성 규칙에는 복원정 곡선(GZ Curve) 등에 관한 내용이 다양하게 규정되어 있다. 이 IMO 복원성 규정에는 다양한 항목의 만족 기준이 제시되고 있으나, 선박을 운항하는 선장에게 선박의 복원성능을 종합적이며, 간편하게 제공할 수 있는 방법은 부재한 상황이다. 이를 위해 본 연구에서는 복원성을 하나의 값으로 표현할 수 있는 지수를 개발하였다. IMO에서 규정한 선박의 6가지 복원성 항목과 대상선박의 적재상황에 따른 복원성 계산결과를 바탕으로 지수산정식이 도출되었다. 또한 개발된 지수산정식을 적용하여 다양한 화물 적재 상황별 복원성 지수(Stability Index)를 계산하였으며, 복원성능의 전반적인 정도를 수치적으로 적절하게 설명할 수 있음을 검증하였다. 이는 선박의 선장에게 복원성 평가하고 판단하는데 도움을 줄 것으로 판단된다.

The evaluation of implant stability measured by resonance frequency analysis in different bone types

Naser Sargolzaie,Sarah Samizade,Hamidreza Arab,Habibollah Ghanbari,Leila Khodadadifard,Amin Khajavi 대한구강악안면외과학회 2019 대한구강악안면외과학회지 Vol.45 No.1

Objectives: Bone density seems to be an important factor affecting implant stability. The relationship between bone density and primary and secondary stability remains under debate. The aim of this study was to compare primary and secondary stability measured by resonance frequency analysis (RFA) between different bone types and to compare implant stability at different time points during 3 months of follow-up. Materials and Methods: Our study included 65 implants (BioHorizons Implant Systems) with 3.8 or 4.6 mm diameter and 9 or 10.5 mm length in 59 patients. Bone quality was assessed by Lekholm–Zarb classification. After implant insertion, stability was measured by an Osstell device using RFA at three follow-up visits (immediately, 1 month, and 3 months after implant insertion). ANOVA test was used to compare primary and secondary stability between different bone types and between the three time points for each density type. Results: There were 9 patients in type I, 18 patients in type II, 20 patients in type III, and 12 patients in type IV. Three implants failed, 1 in type I and 2 in type IV. Stability values decreased in the first month but increased during the following two months in all bone types. Statistical analysis showed no significant difference between RFA values of different bone types at each follow-up or between stability values of each bone type at different time points. Conclusion: According to our results, implant stability was not affected by bone density. It is difficult to reach a certain conclusion about the effect of bone density on implant stability as stability is affected by numerous factors.

이동로봇의 횡방향 안정성 증대를 위한 기구

정상국(S. G. Jung),최용제(Y. J. Choi) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월

This paper presents the mechanism to increase lateral stability of a mobile robot using an energy stability margin theory. Previous measure of stability used in a wheeled mobile robot has been based on a static stability margin. However, the static stability margin is independent of the height of the robot and does not provide sufficient measure for the amount of stability when the terrain is not a horizontal plane. In this work, the energy stability margin theory, which is dependent on robot’s height is used to develop a 2 dof mechanism to increase lateral stability. This proposed mechanism shifts the center of gravity of the robot to the point where the energy stability margin is maximized and overall stability of the robot equipped with this mechanism will be increased.

12주간의 코어 안정화 운동이 태권도 품새 선수들의 체력 및 안정성에 미치는 영향

양대승 대한운동학회 2014 아시아 운동학 학술지 Vol.16 No.3

[PURPOSE] The purpose of this study was to compare and contrast the physical fitness and stability of poomsae players and non-players who participated the core stability training and to understand the effects of core stability training. [METHOD] Nineteen Taekwnodo poomsae players were recruited using random sampling from G university in kyung-gi province. The subjects were divided into two groups (exercise group, n=9, control group, n=10) and measured pre - post tests of muscular strength, muscle endurance, flexibility, agility and stability. The date were analyzed utilizing two-way repeated ANOVA, paired t-test, and independent t-test. [RESULT] 1) The results showed a significant inter-relationship (p=.001) among muscular strength, muscle endurance, flexibility, and agility. From the results of post-hoc test, there were significant relationships among muscular strength, muscle endurance, and flexibility (p=.001), and agility (p=.008) after the core stability training in exercise group. Also, the results showed that significant relationships in muscular strength (p=.005), muscle endurance (p=.028), flexibility (p=.001), agility (p=.008) between groups. 2) There was a significant relationship (p=.037) in both feet overall stability index. From the post-hoc test of timing, there was also a significant relationship in both feet overall and both feet anterior and posterior (p=.049) after the core stability training in exercise group. [CONCLUSION] There was a positive effect on muscular strength, muscle endurance, flexibility, agility, both feet overall stability, and both feet anterior and posterior stability in exercise group attended core stability training. These results indicated that the poomsae players' core muscle were strengthened through the core stability training. Also, it is believed that the core stability training would increase capabilities of balance control and stable posture in the trial of clear movement using central axis of body and a process of connecting movements during the poomsae demonstration. [목적] 본 연구의 목적은 코어 안정화 운동에 참여한 품새 선수와 비 참여 품새 선수의 체력, 안정성을 비교·분석하여 코어 안정화 운동의 효과를 알아보는 것이다. [방법] G대학교 품새 선수 19명을 무선할당(random sampling)을 통해 운동군 9명과 대조군 10명으로 분류한 후 근력, 근지구력, 유연성, 민첩성, 안정성을 사전·사후 측정하였다. 자료분석은 SPSS 21.0의 하위 프로그램을 이용하여 기술통계치와 이원반복변량분석(two-way repeated ANOVA)을, 사후검증은 paired t-test와 independent t-test를 실시하였다. [결과] 1) 근력, 근지구력, 유연성, 민첩성에서 상호작용효과(p=.001)가 있었으며, 사후검증 결과 운동군에서 코어 안정화 운동 후 근력․근지구력․유연성(p=.001), 민첩성(p=.008)에서, 그룹 간에도 근력(p=.005); 근지구력(p=.028), 유연성(p=.001), 민첩성 (p=.008)에서 통계적으로 유의한 차이가 나타났다. 2) 양발 전체의 안정성에서 상호작용효과(p=.037)가 있었으며, 시기에 따른 사후검증 결과 운동군에서 코어 안정화 운동 후 양발 전체(p=.037), 양발 전․후(p=.049)에서 유의한 변화가 나타났다. [결론] 코어 안정화 운동에 참여한 운동군에서 체력의 하위요인인 근력, 근지구력, 유연성, 민첩성과 양발 전체의 안정성, 양발 전후의 안정성에서 긍정적인 변화가 나타났다. 이러한 변화는 코어 안정화 운동을 통해 품새 선수들의 코어근육이 강화되었음을 의미하며, 품새 시연 시 신체의 중심축을 활용한 절도 있는 동작의 구현과 동작간의 연결과정에서 안정적인 자세 유지 그리고 균형조절 능력을 증진시킬 것으로 사료된다.