• 해양환경안전학회지
• /
• 제22권3호
• /
• pp.278-285
• /
• 2016

The key features of maritime accidents are the change of their attributes by new risks from time to time. To prevent maritime accidents in Korea, the impacts by new risks on domestic safety environments should be identified or predicted. The purpose of this paper is to find the hazard factors by new risks on maritime safety in Korea. The meaning of new risks is the elements of accident hazard which is compiled from new or rare or unprecedented events in the worldwide maritime transportations. The problems of new risks are the lacks of optimum countermeasures to mitigate accident risks. Using the questionnaires with 152 event scenarios classified by 20 accident causes, the hazard identification and risk analysis of new risks was performed based on the Formal Safety Assessment (FSA) by IMO. A total of 22 Influence Diagrams, which is to depict the transit flows between accident causes to consequences, is used in the construction of 152 event scenarios. A total of 20 accidents causes is the same contents as the causation factors represented in Statistical Year Book for Maritime Accidents of Korean Maritime Safety Tribunals. After defining the evaluation equations to the response results of questionnaires by 46 experts, the work for risk analysis is carried out. As results from the analysis of 152 scenarios, it is known that the root cause to affect on maritime safety in Korea is the pressure of business competition and it led to the lacks of well experienced crews, the overload of vessel operations and crew's fatigue. In addition, as results from the analysis of 20 accident causes, the three accident causes are to be candidate as main issues in Korea such as the inadequate preparedness of departure, the neglecting of watch keeping in bridge and the inadequate management of ship operations. All of the results are thought to be as basic hazard factors to safety impediments. It is thus found that the optimum Risk Control Options to remove the hazard factors and to mitigate consequences required are the following two factors: business competition and crewing problems.

• 디지털융복합연구
• /
• 제12권2호
• /
• pp.335-341
• /
• 2014

사용자 스마트폰에서 네트워크 비디오를 실시간으로 재생하려면, 서버가 비디오 콘텐츠를 스트리밍 방식으로 전송해야 한다. 일반적으로 상거래 서버는 유료 가입자 인증과 콘텐츠 분배를 담당한다. 단점은 사용자들의 서비스 요구가 급증하면 서버의 과부하, 전송 대역폭의 제한으로 고객에게 돌아가는 서비스 품질이 저하된다는 것이다. P2P 프로토콜은 콘텐츠를 보유한 사용자가 서버 역할을 분담하기 때문에 수요가 집중될 수록 서비스 품질이 좋아진다. 하지만 P2P 프로토콜은 분산된 서버를 제어할 수 없기 때문에 불법 콘텐츠 분배가 가능하여 상거래 용도로 적합하지 않다. 본 논문에서는 P2P 기반의 모바일 상거래에 적합한 동적 그룹 인증 기법을 제안한다. 제안한 기법은 공통키 생성, 공통키 업데이트, 그룹 서명 및 검증 프로토콜로 구성된다. 그룹을 구성하는 시더의 가입과 탈퇴를 반영할 수 있고, 하이브리드 P2P 기반의 상거래 모델에 적용되어 상거래 서비스는 중앙 서버가 담당하고 콘텐츠는 P2P 기반으로 분배할 수 있다.

• 치위생과학회지
• /
• 제14권2호
• /
• pp.114-122
• /
• 2014

본 연구는 직무스트레스 요인을 파악하고, 스트레스 반응에 있어 매개변수의 영향력을 분석하고자 하였다. 치과의료기관에 근무하고 있는 임상치과위생사 243명을 대상으로 실시한 결과 다음과 같은 결론을 얻었다. 첫째, 일반적 특성, 업무 특성에 따른 스트레스 반응을 분석한 결과 위장장애 인식도는 26세 이상, 대학교 이상 졸업자, 계약직, 4년 미만 경력자, 치과병원 근무자, 상담 및 데스크 업무자, 평직원에서 더 높았다(p<0.05). 근육 통증은 25세 이하, 4년 미만의 경력자, 치과병원 근무자, 일일 환자수가 64명 이상, 평직원, 주 6일 이상 근무자, 일일 8시간 이상 근무자 및 점심시간에 휴식을 취하지 못하는 집단에서 더 많이 인식하였다(p<0.05). 우울증 인식도는 남자와 26세 이상, 대학교 이상 졸업자, 기혼자, 월 급여가 180만원 이상, 치과병원 근무자, 상담 및 데스크 업무자 및 주 6일 이상 근무 집단에서 더 높았다(p<0.05). 이직 의도는 26세 이상, 대학교 이상 졸업자, 월 급여가 180만원 이상, 4년 이상의 경력자, 일일 환자 수가 64명 미만, 주 6일 이상 근무자, 야간근무자에서 더 높았다(p<0.05). 둘째, 직무스트레스와 매개요인에 따른 스트레스 반응을 분석한 결과 위장장애와 근육 통증은 근무환경이 나쁘고 역할 갈등과 과부하가 높으며, 공격적인 성격에 가까울수록 더 높았다(p<0.01). 우울증 인식도는 근무환경이 나쁘고 역할 갈등과 과부하가 높으며, A형 성격에 가깝고 자존감이 낮을수록 더 높았다. 이직 의도는 근무환경이 나쁘고 역할 갈등과 과부하가 높으며, A형 성격에 가깝고 상사 동료의 사회적 지원이 적을수록 더 높았다(p<0.01). 셋째, 직무스트레스와 신체적 불편감, 우울증 인식도의 관계에서 매개변수는 성격유형으로, A형 성격에 가까울수록 신체적 불편감과 우울증 인식도가 더 높았다(p<0.05). 직무스트레스와 이직 의도의 관계에서 매개변수는 상사 동료의 사회적 지원으로, 상사와 동료의 사회적 지원이 낮을수록 이직 의도가 더 높았다(p<0.05). 본 연구결과 직무스트레스와 스트레스 반응의 관계에서 성격유형과 상사 동료의 사회적 지원은 중요한 매개요인임을 알 수 있었다. 따라서 치과위생사가 직무를 수행하는 동안 스트레스로 인한 부정적 결과를 감소시키기 위하여 자신의 성격을 파악하고 이를 조절할 수 있는 능력 개발을 위해 교육이 지원되어야 하며, 조직적이고 구조적 차원에서 사회적 지원을 더욱 증가시켜야 한다. 특히 직무수행 과정에서 성취감을 느낄 수 있도록 격려와 인정을 제공해주는 시스템을 확대하여야 할 것이다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제14권2호
• /
• pp.113-118
• /
• 2010

The sensory system is developed and optimized by experiences given in the early phase of life in association with other regions of the nervous system. To date, many studies have revealed that deprivation of specific sensory experiences can modify the structure and function of the central nervous system; however, the effects of sensory overload remains unclear. Here we studied the effect of overloading the taste sense in the early period of life on the synaptic plasticity of rat hippocampus and somatosensory cortex. We prepared male and female Sprague Dawley rats with ad libitum access to a 0.1% saccharin solution for 2 hrs per day for three weeks after weaning on postnatal day 22. Saccharin consumption was slightly increased in males compared with females; however, saccharin intake did not affect chow intake or weight gain either in male or in female rats. We examined the effect of saccharin-intake on long term potentiation (LTP) formation in hippocampal Schaffer collateral pathway and somatosensory cortex layer IV - II/III pathways in the 6-week old saccharin-fed rats. There was no significant difference in LTP formation in the hippocampus between the control group and saccharin-treated group in both male and female rats. Also in the somatosensory cortex, we did not see a significant difference in LTP among the groups. Therefore, we conclude that saccharin-intake during 3~6 weeks may not affect the development of physiological function of the cortical and hippocampal synapses in rats.

• 대한치과보철학회지
• /
• 제40권5호
• /
• pp.507-524
• /
• 2002

Load transfer of implant overdenture varies depending on anchorage systems that are the design of the superstructure and substructure and the choice of attachment. Overload by using improper anchorage system not only will cause fracture of the framework or screw but also may cause failure of osseointegration. Choosing anchorage system in making prosthesis, therefore, can be considered to be one of the most important factors that affect long-term success of implant treatment. In this study, in order to determine the effect of anchorage systems on load transfer in mandibular implant overdenture in which 4 implants were placed in the interforaminal region, patterns of stress distribution in implant supporting bone in case of unilateral vertical loading on mandibular left first molar were compared each other according to various types of anchorage system using three-dimensional photoelastic stress analysis. The five photoelastic overdenture models utilizing Hader bar without cantilever using clips(type 1), cantilevered Hader bar using clips(type 2), cantilevered Hader bar with milled surface using clips(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4), and Hader bar using clip and ERA attachments(type 5), and one cantilevered fixed-detachable prosthesis(type 6) model as control were fabricated. The following conclusions were drawn within the limitations of this study, 1. In all experimental models. the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. Maximum fringe orders on ipsilateral distal implant supporting bone in a ascending order is as follows: type 5, type 1, type 4, type 2 and type 3, and type 6. 3. Regardless of anchorage systems. more or less stresses were generated on the residual ridge under distal extension base of all overdenture models. To summarize the above mentioned results, in case of the patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant and unfavorable antero-posterior spread. selecting resilient type attachment or minimizing distal cantilever bar is considered to be appropriate methods to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.

• 한국산업정보학회:학술대회논문집
• /
• 한국산업정보학회 1999년도 추계공동학술대회 논문집:21세기지식경영과 정보기술
• /
• pp.121-129
• /
• 1999

통신망을 통하여 시간 연속(continuous) 미디어를 전송하면 통신망의 부하 변동에 따라 운송지연(transit delay)이 일정하지 않으므로 수신측에 도착하는 패킷간에 원래의 시간 관계가 유지되지 않는 비동기 현상이 나타난다. 현재 제안된 여러 동기화 방안들은 운송 지연 특성을 보장하는 자원 보장형 통신망과 운송 지연 특성이 보장되지 않아 변화의 폭이 큰 자원 비보장형 통신망 환경을 고려한 2가지 형태가 존재한다. 자원 보장형 통신망은 최소 및 최대 운송 지연 시간을 예약이나 협상을 통해 전송 기간동안 계속 유지하는 반면, 자원 비보장형 통신망에서는 가능한 최대의 대역폭을 사용하는 최대 노력 (best-effort) 서비스를 사용한다. 이 논문은 패킷망이나 인터넷과 같은 자원 비보장형 통신망 환경에서 통신망의 부하 변화에 동적으로 적응하여 동기화된 전달(playout)을 제공하는 미디어내 동기화 방안(Inter-media Synchronization)에 관한 것이다. 본 논문에서 제안하는 방안은 데이터 전송 경로의 운송 지연 통계치를 사용하여 다음 전송할 패킷의 운송 지연을 추정하여 송신 시간을 조절함으로써, 통신망의 부하로 인한 운송 지연의 변화가 크더라도 수신 패킷의 도착 시간을 일정한 범위 내로 유지한다. 또한, 통신망의 부하가 지속적으로 증가하여 연속되는 패킷의 운송 지연이 점차 늘어나면 전송률을 높이는 것만으로 문제를 해결할 수 없을 뿐만 아니라 오히려 혼잡을 발생시킬 가능성이 있다. 따라서, 통신망의 대역폭에 맞추어 일부 전송 패킷을 폐기함으로써 실제적인 전송률을 조정하였다. 이 방안은 수신측의 버퍼가 충분하지 않거나, 버퍼 지연 시간이 제한적인 대화형 응용에서 연속 미디어를 전송하는데 적합하다.았으며 tall fescue는 T, V, V + T(1 : 1로 피복한 종자)에서 가장 높게 나타났다(P<0.01). 종자피복에 있어서 red clover와 tall fescue 공히 접착제는 CF나 PVA로 하고 고형물질은 V나 V+T(1:1)로 피복함으로서 가장 좋은 피복효과를 얻을 수 있었다.. 쟁점 및 과제들이 제시되었다. cells of these species contained considerable to large amount of neutral mucin, and small to considerable amount of acid mucin, Most of the medium sized and small mucous cells contained neutral mucin and sialomucin, but a few mucous cells contained neutral mucin and strongly sulfomucin or neutral combined with strongly sulfomucin and sialomucin. Most of the esophageal mucous cells pf Bryzoichthys lysimus contained small amount of neutral mucin, while on the other hand a feww mucous cells contained small amount of neutral mucin and minimal amount of sialomucin. But the esophageal mucous cells of Takifugu pardalis contained considerable amount of neutral mucin only.분해가 더욱 촉진

• The Korean Journal of Physiology
• /
• 제29권2호
• /
• pp.279-289
• /
• 1995

This study was designed 1) to develop a hypertensive animal model in which the blood pressures (BPs) of symmetric regions (right and left upper extremities) are significantly different and 2) to test the effect of BP per se on the contractility and endothelium-dependent relaxation of vascular smooth muscle. Rabbits were anesthetized with sodium pentobarbital and ventilated with room air via animal respirator. The transverse aorta was exposed through the left second intercostal space and the lumen of the aorta was narrowed partially by ligation using 3-0 silk and a probe at a point between the origins of the brachiocephalic trunk and the left subclavian artery. Four to eight weeks postoperatively, BPs were measured in the carotid artery as the high BP area (proximal to coactation site) and in the femoral artery as the low BP area (distal to coarctation site). In the animal model, pressure-overload hypertension was developed and the BP of the right subclavian artery was higher than that of the left subclavian artery. The concentrations of circulating epinephrine, norepinephrine, angiotensin I, and angiotensin II were measured. The right and left subclavian arteries and their branches were used for isometric tension recording in organ baths and their responsiveness to phenylephrine, serotonin, acetylcholine, and sodium nitroprusside were examined. The BPs of carotid and femoral artery in control animals were $116{\pm} 12/75{\pm}9\;mmHg (mean ${\pm}SEM$) and $130{\pm}16/68{\pm}9\;mmHg$ respectively, while those of carotid and femoral artery in the hypetensive animals were $172{\pm}6/111{\pm}10\;mmHg$ and 136{\pm} 4/100 {\pm}9\;mmHg$ respectively. There were no significant differences in the concentrations of circulating epinephrine, norepinephrine, angiotensin I, and angiotensin II between controls and the animal models. No significant differences were found in the vascular sensitivities to phenylephrine and serotonin between the high pressure-exposed vessels and the low pressure-exposed vessels. However, the endothelium-dependent relaxation to acetylcholine and nitroprusside-induced relaxation showed significant differences between the high pressure-exposed and the low pressure-exposed subclavian arteries. From the above results, we suggest that the contractility of vascular smooth muscle is unchanged by the elevated pressure per se. However, the endothelium-dependent relaxation to acetylcholine and the nitroprusside-induced relaxation are attenuated by pressure.

• 한국콘텐츠학회논문지
• /
• 제13권3호
• /
• pp.251-259
• /
• 2013

본 연구는 간호사의 직무스트레스와 자아존중감이 정신건강에 미치는 영향을 파악하기 위한 서술적 조사 연구이다. 연구대상은 D시에 소재한 3개 종합병원(600병상이상의 C종합병원, E종합병원, G종합병원) 간호사 457명으로 2011년 7월 4일부터 7월 29일까지 조사하였다. 수집된 자료는 n (%), t-test, ANOVA, Scheffe test, Pearson's Correlation Coefficient 및 multiple regression analysis으로 분석하였다(SPSS 18.0). 연구결과는 다음과 같다. 첫째, 직무스트레스는 평균 171.5점, 자아존중감은 평균 28.9점, 정신건강은 평균 76.1점으로 나타났다. 둘째, 대상자의 정신건강은 결혼유무, 교육수준, 근무병동, 근무형태에 따라 유의한 차이가 있는 것으로 나타났다. 셋째, 정신건강은 직무스트레스(r=.32, p<.001) 및 자아존중감(r=-.63, p<.001)과 유의한 상관관계가 있는 것으로 나타났다. 넷째, 정신건강에 영향을 미치는 요인은 직무스트레스의 하부영역에서 직무자율성 결여, 업무량과중, 부적절한 대우와 보상, 대인관계 문제, 그리고 자아존중감과 일반적 특성에서 근무형태(3교대)로 확인되었으며, 42.2%의 설명력을 나타냈다. 결론적으로 본 연구는 간호사의 정신건강관련 요인으로 직무스트레스와 자아존중감의 역할을 실증적으로 확인하였다는 점에서 의의를 찾을 수 있다. 따라서 간호사의 정신건강 문제 예방 및 중재를 위한 프로그램 개발에 기초자료를 제공하고자한다.

• Journal of Periodontal and Implant Science
• /
• 제37권1호
• /
• pp.137-150
• /
• 2007

CADIA(Computer-assisted densitometric image analysis) method is used to analyze bone density changes around the implants. The usefullness and reproducibility of the method was assessed. We tried to find out if there is any possibility to quantitiate and qualitify peri-implant bone density change as time passes. And we concluded that this newly developed linear analysis is efficient for analyzing peri-implant bone density change non-Invasively. In this study, 2152 machined $Br{\aa}nemark$ fixtures installed from 1994 to 2002 in the department of Periodontics, Dental hospital of College of Dentistry, Yonsei University were included. Of these fixtures 22 radiographically analyzable failed fixtures were used as experimental group, and 22 successful implants placed in the same patient were used as control group. 1. 57 out of 1635 machined $Br{\aa}nemark$ standard and Mk II implants system failed, the survival rate was 96.5%. And 11 out of 517 machined $Br{\aa}nemark$ Mk III and Mk IV implants system failed, the survival rate was 97.9%. Total survival rate was 96.8%. 2. 22 failed implants were used for the analysis, 10 of which failed before prosthetic treatment due to infection and overheating. 12 failed due to overload after prosthetic treatment, 63.6% of which failed during the early phase of functional loading, i, e. before 1 year of loading. 3. Bone density change values around coronal region of the failed implants were $-6.54{\pm}6.35$, middle region were $-3.53{\pm}5.78$, apical region were $-0.75{\pm}10.33$, resulting in average of $-3.71{\pm}8.03$. 4. Bone density change values around coronal region of the successful implants were $4.25{\pm}4.66$, middle region were $6.33{\pm}5.02$, apical region were $9.89{\pm}4.67$, resulting in average of $6.27{\pm}5.29$. 5. There was a statistically significant difference between two groups (p<0.01). In conclusion, the linear analysis method using computer-assisted densitometric image analysis could be a useful method for the analysis of implants, and could be used for future implant researchs.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제10권4호
• /
• pp.491-498
• /
• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.