• 제목/요약/키워드: nuclear tensions

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Model of the onset of liquid entrainment in large branch T-junction with the consideration of surface tension

  • Liu, Ping;Shen, Geyu;Li, Xiaoyu;Gao, Jinchen;Meng, Zhaoming
    • Nuclear Engineering and Technology
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    • 제53권3호
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    • pp.804-811
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    • 2021
  • The T-junction exists widely in industrial engineering, especially in nuclear power plants, which plays an important part in nuclear power reactor thermal-hydraulics. However, the existing prediction models of the liquid entrainment are mainly based on the small branches or small breaks while there are a few researches for large branches (d/D > 0.2). Referring to the classical models about the onset of liquid entrainment of the T-junction, most of previous models regard liquid as ideal working fluid and ignore surface tension. This paper aims to study the effect of surface tension on the liquid entrainment, and develops an improved model based on the reasonable assumption. The establishment of new model employs the methods of force analysis, dimensional analysis. Besides, the dimensionless Weber number is adopted innovatively into the model to show the effect of surface tension. What is more, in order to validate the new model, three kinds of working fluids with different surface tensions are creatively adopted in the experiments: water, silicone oil and ethyl alcohol. The final results show that surface tension has a nonnegligible effect on the onset of liquid entrainment in large branch T-junction. The new model is well matched with the experimental data.

북한의 대외정책 기조와 전망 (The North Korea's Foreign Policy Stance and Prospect)

  • 김성우
    • 융합보안논문지
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    • 제14권6_1호
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    • pp.57-63
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    • 2014
  • 한반도는 탈냉전이라는 역사적 변화에도 불구하고 냉전적 구조가 해제되지 않고 북한의 대남도발은 계속되고 있다. 북한의 천안함 폭침과 연평도 포격도발은 파국적인 남북관계 초래와 동북아 불안정의 요인으로 작용하고 있다. 북한의 도발은 미국과 한국 및 북한 내부 요인이 북한의 의사결정체계에서 복합적으로 작용하여 군사 비군사적 수단에 의해 자행되고 있다. 북한은 한반도의 적화통일이라는 전략기조을 유지하기 때문에 공세적으로 지속될 수밖에 없을 것이다. 북한의 대외정책은 지속성과 상황에 따라 변화하는 양면성을 지니고 있다. 북한 대외정책의 목표와 이념은 비교적 일관성 있게 지속하고 있지만, 정책전개의 전략 전술과 행동 유형에서는 상당한 변화가 있다. 즉, 지속성은 곧 국가 체제유지와 국가 생존 명분의 문제이며, 변화는 지속성과 명분을 유지시키고 발전하기 위한 전술적 종속개념에 해당한다. 합리적인 시각으로 본다면 북한의 대외정책 기조는 군사력과 핵무기 개발을 생존수단으로 삼아 긴장을 조성하여 외교적, 경제적 보상을 얻는 외교방식을 과감하게 탈피하여야 하며 국제사회에 참여하여 하나의 국가로서 국제관례를 지키는 자세를 견지해야 하나 여러 가지 여건상 기존 대외정책 방향을 고수하고 있다.

국방환경변화에 따른 군 조직진단체계 발전방향 연구 (Research on development of organization analysis system in accordance with the defense environment changes)

  • 김기현
    • 안보군사학연구
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    • 통권13호
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    • pp.43-81
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    • 2016
  • Security environment we face in the Korean Peninsula is unexpectable. Tensions between Seoul and Pyeongyang and its threats are continuously evolving. Kim Jung Un will keep on conducting provocations and DPRK's isolation will result uncertainty to their objective and intention. KPA is centered on ground forces with conventional weapons but they possess modernized missiles and nuclear capabilities. What's more concerning is that North Korea continuously pursue and develop nuclear weapons and missile capabilities. Pursuing defense reform is inevitable for the ROK to deal adequately against the security threats posed by the North and to prepare for the environment of future warfare. If we are satisfied with the current capabilities then our military capabilities and security status will retrogress. We have to reorganize our units to make a small but FMC, smart military organization. Organization analysis is an urgent issue for reorganizing units. However, it isn't an easy task to reform an organization. There are vague parts for analysis and strong resistance from the people within the organization. Therefore should not focus on the reduction of people and the organization. Organization reform should be done with the acknowledgement of most of the personnel and should focus on the task and its method. These should be reflected to the organization analysis.

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한미동맹과 대량무기 확산방지구상에 대한 해석 (Interpretation of the ROK-U.S. Alliance and PSI)

  • 김주원
    • 한국정보통신학회논문지
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    • 제16권5호
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    • pp.1102-1112
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    • 2012
  • 미국의 한반도 정책은 비핵화이다. 미국정부는 북한의 핵위협을 제거하기 위해 군사행동의 가능성을 고려했었다. 군사행동 고려는 1993년 중반부터 1994년 중반까지 정점에 달했다. 그러한 공격은 직접적으로 한국전을 일으켰을 것이다. 당시 북핵위기는 북미협상과 한미동맹에 의해 해결되었다. PSI의 목적은 지구적 또는 지역적 안보에 심각한 위협을 일으키는 국가나 비국가행위자에게 대량살상무기, 운반체계, 관련 물질의 확산을 막거나 적어도 억제하는 것이다. PSI의 가장 논쟁의 여지가 있는 활동은 차단이다. 북한은 구상에 대해 심각한 우려를 표명하면서 다음과 같이 언급하였다. 무기를 개발하고, 배치하고, 수출하는 것은 주권이다. 그리고 자신들의 선박에 대한 차단은 선전 포고로 간주할 것이다. 한국이 북한선박에 대한 차단을 시행하면 북한은 도발로 대응할 것이므로 한반도의 긴장은 극적으로 증가할 것이다. 한국은 한미동맹과 남북관계를 고려해야하기 때문에 PSI에 매우 조심스럽게 접근하지 않을 수 없다.

호흡부전증에세 호기말 양압호흡법 치료 전후의 폐혈류역학적 변화에 관한 연구 (A Study on the Pulmonary Hemodynamic Changes before and after PEEP in ARDS)

  • 정준기;신성해;강신광;박성기;이명철;조보연;고창순;김용락;김광우
    • 대한핵의학회지
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    • 제18권1호
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    • pp.45-53
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    • 1984
  • The purpose of this study is to observe the changes of pulmonary capillary permeability and various hemodynamic parameters before and after Positive End-Expiratory Pressure(PEEP) in Adult Respiratory Distress Syndrome (ARDS). Using a canine oleic acid induced ARDS model, we measured the pulmonary capillary permeability with a slope of lung: heart radioactivity ratio, hemodynamic parameters with Swan-Ganz catheter and blood gas tensions. 1) In normal and ARDS dogs, the PEEP didn't significantly influence the slope of lung: heart radioactivity ratio. But in ARDS group the slope index was increased compaired with that of control group (p<0.05). 2) Also in ARDS group, $PaO_2$ was significantly decreased, and $PaCO_2,\;PvCO_2$, MPAP, $AaDO_2$, Qs/Qt were significantly increased compared with those of control group (p<0.05). 3) In normal dogs, the PEEP didn't influence blood pH or gas tension, $AaDO_2$, Qs/Qt, or hemodynamics. 4) In ARDS dogs, however, the PEEP significantly increased $PaO_2$ and decreased $AaDO_2$, Qs/Qt (p<0.05).

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천안함 폭침 이후 북한의 군사도발 양상과 전망 (Trends and Prospects of N. Korea Military Provocations After the Sinking of ROKS Cheon-an)

  • 김성만
    • Strategy21
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    • 통권34호
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    • pp.58-92
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    • 2014
  • Even after S. Korea took 5.24 Measure(24 May 2014), N. Korea has not stopped raising provocations such as the shelling of Yeonpyeong Island, electronic and cyber attacks. To make matters worse, the communist country lunched long-range missiles(twice) and conducted 3rd nuclear test, escalating tensions which could possibly lead to an all-out war. Korean Government failed to respond properly. However, escalation into an all-out war was deterred by the CFC immediately carrying out its peacetime duty(CODA). The US made a rapid dispatch of its augmentation forces(Aircraft carrier, nuclear-powered submarine, strategic bomber, F-22) to the Korean Peninsula. In recognition of the importance of the Combined Forces Command, since May 2013 the Park Geun-Hye Administration has been pushing ahead with re-postponement of Wartime Operational Control Transfer(which initially meant the disassembling of the CFC as of 1 December 2015) More recently, there has been a series of unusual indicators from the North. Judging from its inventory of 20 nuclear weapons, 1,000 ballistic missiles and biochemical weapons, it is safe to say that N. Korea has gained at least war deterrence against S. Korea. Normally a nation with nuclear weapons shrink its size of conventional forces, but the North is pursuing the opposite, rather increasing them. In addition, there was a change of war plan by N. Korea in 2010, changing 'Conquering the Korean Peninsula' to 'Negotiation after the seizure of the Greater Seoul Metropolitan Area(GSMA)' and establishing detailed plans for wartime projects. The change reflects the chain reaction in which requests from pro-north groups within the South will lead to the proclamation of war. Kim, Jeong-Un, leader of N. Korean regime, sent threatening messages using words such as 'exercising a nuclear preemptive strike right' and 'burning of Seoul'. Nam, Jae-June, Director of National Intelligence Service, stated that Kim, Jung-Un is throwing big talks, saying communization of the entire Korean Peninsula will come within the time frame of 3 years. Kim, Gwan-Jin, Defense Minister, shared an alarming message that there is a high possibility that the North will raise local provocations or a full-fledged war whenever while putting much emphasis on defense posture. As for the response concept of the Korean Government, it has been decided that 'ROK·US Combined Local Provocation Counter-Measure' will be adopted to act against local provocations from the North. Major provocation types include ▲ violation of the Northern Limit Line(NLL) with mobilization of military ships ▲ artillery provocations on Northwestern Islands ▲ low altitude airborne intrusion ▲ rear infiltration of SOF ▲ local conflicts within the Military Demarcation Line(MDL) ▲ attacking friendly ships by submarines. Counter-measures currently established by the US involves the support from USFK and USFJ. In order to keep the sworn promise, the US is reinforcing both USFK and USFJ. An all-out war situation will be met by 'CFC OPLAN5027' and 'Tailored Expansion Deterrence Forces' with the CFC playing a central role. The US augmentation forces stands at 690,000 troops, some 160 ships, 2,000 aircraft and this comprise 50% of US total forces, which is estimated to be ninefold of Korean forces. The CFC needs to be in center in handling both local provocations and an all-out war situation. However, the combat power of S. Korean conventional forces is approximately around 80% of that of N. Korea, which has been confirmed from comments made by Kim, Gwan-Jin, Defense Minister, during an interpellation session at the National Assembly. This means that S. Korean forces are not much growing. In particular, asymmetric capabilities of the North is posing a serious threat to the South including WMD, cyber warfare forces, SOF, forces targeting 5 Northwestern Islands, sub-surface and amphibious assault forces. The presence of such threats urgently requires immediate complementary efforts. For complementary efforts, the Korean Government should consider ① reinforcement of Korean forces; putting a stoppage to shrinking military, acquisition of adequate defense budget, building a missile defense and military leadership structure validity review, ② implementation of military tasks against the North; disciplinary measures on the sinking of ROKS Cheon-an/shelling of Yeonpyeong Islands, arrangement of inter-Korean military agreements, drawing lessons from studies on the correlation between aid for N. Korea, execution of inter-Korean Summit and provocations from the North, and ③ bolstering the ROK·US alliance; disregarding wartime operational control transfer plan(disassembling of CFC) and creation of a combined division.

문재인 정부 1년의 평가와 전망 (The First Year of the Moon Jae-In Government: An Assessment)

  • 강원택
    • 의정연구
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    • 제24권1호
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    • pp.5-29
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    • 2018
  • 이 글은 문재인 대통령 임기 첫 해를 평가하고, 향후의 국정 운영을 위해 개선이 필요한 점에 대해 논의한다. 전체적으로 볼 때 문재인 정부의 1년은 대체로 성공적이었다고 할 수 있다. 박근혜 대통령에 대한 탄핵으로 인해 조기 대선이 실시되어, 문재인 대통령은 대통령직 인수위원회의 과정을 거치지 못한 채 곧바로 국정운영에 나서게 되었다. 그럼에도 불구하고 그 후 비교적 신속하게 정치적 안정을 되찾았고 새로운 국정의 방향을 제시했다. 무엇보다 문재인 대통령의 지지도가 상당히 높은 수준으로 거의 1년 내내 유지되었다는 점이 중요했다. 70%를 전후로 하는 높은 지지율은 지난 1년 동안 대통령의 국정 주도와 정치적 안정에 중요하게 작용했다. 그러나 해결해야 할 과제도 적지 않다. 청와대 중심의 국정 운영, 야당과의 대결적 구조, 집권당의 무기력 등의 문제를 극복할 수 있는 국정운영 방식의 변화가 필요하며, 문재인 정부의 공정성, 도덕성에 치명적 해를 미칠 수 있는 부패 스캔들이 발생하지 않도록 이에 대한 철저한 내부 단속이 필요할 것이다. 적폐청산 역시 관련 인적 교체와 관련 인물에 대한 사법처리를 넘어서 재발을 막을 수 있는 제도적, 법적 장치를 서둘러 마련할 필요가 있다. 또한 임기 중반으로 가는 만큼 현재의 협소한 인재 풀을 확대할 필요가 있으며, 공약 역시 우선순위와 타당성을 따져 현실성 있는 접근을 하는 것이 적절해 보인다. 지난 1년간의 높은 지지율이 향후에도 지속될 것으로 기대할 수 없는 만큼 남은 임기 기간에 대한 세심한 관리가 필요하다.