• 제목/요약/키워드: far wake

검색결과 54건 처리시간 0.021초

Laser Acceleration of Electron Beams to the GeV-class Energies in Gas Jets

  • Hafz, Nasr A.M.;Jeong, Tae-Moon;Lee, Seong-Ku;Choi, Il-Woo;Pae, Ki-Hong;Kulagin, Victor V.;Sung, Jae-Hee;Yu, Tae-Jun;Cary, John R.;Ko, Do-Kyeong;Lee, Jong-Min
    • Journal of the Optical Society of Korea
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    • 제13권1호
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    • pp.8-14
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    • 2009
  • In a laser-plasma wakefield accelerator, the ponderomotive force of an ultrashort high intensity laser pulse excites a longitudinal wave or plasma bubble in a way similar to the excitation of a wake wave behind a boat as it propagates on the water surface. Electric fields inside the plasma bubble can be several orders of magnitude higher than those available in conventional RF-based particle accelerator facilities which are limited by material breakdown. Therefore, if an electron bunch is properly phase-locked with the bubble's acceleration field, it can gain relativistic energies within an extremely short distance. Here, in the bubble regime we show the generation of stable and reproducible sub GeV, and GeV-class electron beams. Supported by three-dimensional particle-in-cell simulations, our experimental results show the highest acceleration gradients produced so far. Simulations suggested that the plasma bubble elongation should be minimized in order to achieve higher electron beam energies.

연구·학습윤리 규범 연구개발 (Study and development on ethics code of research-learning)

  • 이재성
    • 철학연구
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    • 제123권
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    • pp.309-346
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    • 2012
  • 황우석 박사 연구팀의 논문조작 사건은 우리 사회에서 그동안 견고하게 이어져오던 학문 연구자와 그 연구 활동에 대한 신뢰를 크게 흔들어놓았다. 이 사건 이후에 우리의 연구자사회와 과학계는 반성 및 성찰 과정을 통해 많은 변화를 겪었다. 우리는 연구자사회가 먼저 나서서 제기된 의혹을 철저하게 규명하려는 능동적인 노력을 보여줄 때에 연구자사회에 대한 신뢰, 연구 활동에 대한 신뢰는 크게 흔들리지 않았음을 경험해왔다. 하지만 연구부정행위에 대해 소극적으로 대응하는 반대의 경우들이 아직은 더 많기에, 우리 연구자사회가 가야 할 길은 여전히 험난하다. 따라서 학문이나 학습 영역의 연구 및 학습 부정행위 사례가 불필요하게 확대 해석되는 일을 막는 것은 연구자 및 학습자 사회 내부에 정치, 경제, 사회 등 제 분야의 갖가지 이해관계들에서 벗어난 자율적인, 또한 의사결정이 합리적으로 이뤄지는 체계를 얼마나 잘 갖추고 있느냐에, 그리고 사회적 사건으로 비화하기 이전에 먼저 이런 부조리를 미리 예방하려는 세심한 체계를 얼마나 잘 갖추고 있느냐에 달려 있다. 이러한 맥락에서 필자는 사후적 차원이 아니라 사전적 차원, 즉 연구자 및 학습자의 자율적 자정 체계 마련을 위한 방법, 즉 연구 학습윤리의 규범 연구가 왜 중요한 것인지를 탐색할 것이다. 논의의 분명한 진행을 위해서는 우선 연구 학습윤리가 무엇인지를 좀 더 분명하게 규명하고 정의할 필요가 있다.(2) 그리고 이 과정에서 연구 학습윤리가 왜 규범화되어야 하는지를 살펴야 할 것이다.(3) 이어서 만일 연구 학습윤리가 규범화될 수 있는 것이라면, 그것이 왜 정당화되어야 하는지를 논증하면서,(4) 이 글을 마무리할 것이다.(5)

한국 남해의 대마난류 변동이 멸치 난$\cdot$자어의 연안역 수송에 미치는 영향 (The Effect of Variations in the Tsushima Warm Currents on the Egg and Larval Transport of Anchovy in the Southern Sea of Korea)

  • 추효상;김동수
    • 한국수산과학회지
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    • 제31권2호
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    • pp.226-244
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    • 1998
  • 한국 남해 멸치 자원의 변동이 남해의 해황 구조와 변화에 어떻게 지배되는지를 규명하기 위해 하계 (8월)와 추계 (11월)에 대마난류계수의 연안 유입 현상과 멸치난$\cdot$자어의 분포 그리고 난수의 연안 유입에 따른 해역의 생물 생산 환경을 조사하였다. 그 결과 다음의 결론을 얻었다. 하계 연안수과 대마난류계수 사이는 수온, 염분, 투명도의 수평경도가 큰 전선이 형성되고 전선역은 흐름의 shear가 크다. 멸치 난$\cdot$자어는 전선을 경계로 연안역이 외해 보다 출현 개체수가 많고 전선에 다량 분포한다. 외해의 난수역은 발생 초기의 멸치 난이 많고, 연안과 전선에서 파급된 warm streamer 역에 전, 후기 자어의 출현이 많다. warm streamer는 대마난류의 세력이 강해져 난류의 주축이 연안으로 접근하는 한계에 주로 나타나며, 고흥 반도가소리도 그리고 욕지도 서쪽에서 반시계 방향으로 연안을 향해 유입된다. warm streamer가 유입되는 연안해역은 반시계 방향의 표층 순환류 (좌선환류)가 형성된다. 난류 접안과 warm streamer의 연안 유입으로 거문도, 소리도, 거제도 주변은 표층의 wake와 저층수의 용승현상이 나타나 용존산소, 부유물질, 영양염의 농도가 크고, warm streamer가 좌선환류를 형성하면서 거문도, 소리도 주변의 연안수가 환류역내로 유입된다. 하계 한국 남해 연안에 산란된 멸치 난$\cdot$자어는 흐름의 수렴역인 대마난류계수와 연안수 사이의 전선에 수렴되어 전선에서 연안으로 파급되는 warm streamer에 의해 연안으로 수송된다. 이때 전선 내측의 연안역은 생물생산력이 크고, 클로로필 및 식물 플랑크톤의 양이 외해의 난수역보다 많아 멸치 자어의 성육에 적합한 환경이 된다 (Fig. 16 Case August). 그러나 멸치 자어의 먹이인 Copepod 양은 난수역이 많아 멸치가 성장함에 따라 연안에서 외해로 이동하게 된다. 추계는 청산도$\~$소리도에 남해 연안수가 형성되고 대마난류계수가 남해 연안에서 점차 멀어짐에 따라 연안수와 대마난류계수 사이에 온도차가 큰 전선이 형성된다. 멸치 난$\cdot$자어의 출현은 연안에서 산란이 거의 일어나지 않고 해역내 표층류가 전반적으로 이안, 동류 함에 따라 매우 낮다. 고흥반도 남쪽과 소리도$\~$욕지도 사이는 하계와 같은 warm streamer는 존재하지 않고, 욕지도 남쪽에 연안수 확장에 따른 보류 혹은 약화된 warm strea-mer의 형태로 소형 warm eddy가 출현한다 (Fig. 16 Case November) 소리도 서쪽의 남해 연안수역은 부유물질, 영양염, 클로로필의 농도가 동쪽의 소리도$\~$거제도 연안에 비해 높다. 소리도$\~$욕지도 연안은 warm streamer 유입에 의한 좌선환류의 약화로 하계와 같은 높은 염양염 농도역은 없으나, 욕지도 남쪽 warm eddy 역 주변에 농도가 높다. 식물 플랑크톤의 양은 하계보다 작으나 Copepod 개체수는 증가 해, 멸치 자어의 초기 생잔에 필요한 먹이 조건은 양호하다. 그러나 산란과 난$\cdot$자어의 연안 수송이 거의 이루어지지 않아 멸치 어장은 대마난류계수가 연안과 가까운 거제도와 대마도 주변으로 이동된다.

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병원 간호행정 개선을 위한 연구 (A Study for Improvement of Nursing Service Administration)

  • 박정호
    • 대한간호학회지
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    • 제3권1호
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    • pp.13-40
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    • 1972
  • Much has teed changed in the field of hospital administration in the It wake of the rapid development of sciences, techniques ana systematic hospital management. However, we still have a long way to go in organization, in the quality of hospital employees and hospital equipment and facilities, and in financial support in order to achieve proper hospital management. The above factors greatly effect the ability of hospitals to fulfill their obligation in patient care and nursing services. The purpose of this study is to determine the optimal methods of standardization and quality nursing so as to improve present nursing services through investigations and analyses of various problems concerning nursing administration. This study has been undertaken during the six month period from October 1971 to March 1972. The 41 comprehensive hospitals have been selected iron amongst the 139 in the whole country. These have been categorized according-to the specific purposes of their establishment, such as 7 university hospitals, 18 national or public hospitals, 12 religious hospitals and 4 enterprise ones. The following conclusions have been acquired thus far from information obtained through interviews with nursing directors who are in charge of the nursing administration in each hospital, and further investigations concerning the purposes of establishment, the organization, personnel arrangements, working conditions, practices of service, and budgets of the nursing service department. 1. The nursing administration along with its activities in this country has been uncritical1y adopted from that of the developed countries. It is necessary for us to re-establish a new medical and nursing system which is adequate for our social environments through continuous study and research. 2. The survey shows that the 7 university hospitals were chiefly concerned with education, medical care and research; the 18 national or public hospitals with medical care, public health and charity work; the 2 religious hospitals with medical care, charity and missionary works; and the 4 enterprise hospitals with public health, medical care and charity works. In general, the main purposes of the hospitals were those of charity organizations in the pursuit of medical care, education and public benefits. 3. The survey shows that in general hospital facilities rate 64 per cent and medical care 60 per-cent against a 100 per cent optimum basis in accordance with the medical treatment law and approved criteria for training hospitals. In these respects, university hospitals have achieved the highest standards, followed by religious ones, enterprise ones, and national or public ones in that order. 4. The ages of nursing directors range from 30 to 50. The level of education achieved by most of the directors is that of graduation from a nursing technical high school and a three year nursing junior college; a very few have graduated from college or have taken graduate courses. 5. As for the career tenure of nurses in the hospitals: one-third of the nurses, or 38 per cent, have worked less than one year; those in the category of one year to two represent 24 pet cent. This means that a total of 62 per cent of the career nurses have been practicing their profession for less than two years. Career nurses with over 5 years experience number only 16 per cent: therefore the efficiency of nursing services has been rated very low. 6. As for the standard of education of the nurses: 62 per cent of them have taken a three year course of nursing in junior colleges, and 22 per cent in nursing technical high schools. College graduate nurses come up to only 15 per cent; and those with graduate course only 0.4 per cent. This indicates that most of the nurses are front nursing technical high schools and three year nursing junior colleges. Accordingly, it is advisable that nursing services be divided according to their functions, such as professional, technical nurses and nurse's aides. 7. The survey also shows that the purpose of nursing service administration in the hospitals has been regulated in writing in 74 per cent of the hospitals and not regulated in writing in 26 per cent of the hospitals. The general purposes of nursing are as follows: patient care, assistance in medical care and education. The main purpose of these nursing services is to establish proper operational and personnel management which focus on in-service education. 8. The nursing service departments belong to the medical departments in almost 60 per cent of the hospitals. Even though the nursing service department is formally separated, about 24 per cent of the hospitals regard it as a functional unit in the medical department. Only 5 per cent of the hospitals keep the department as a separate one. To the contrary, approximately 12 per cent of the hospitals have not established a nursing service department at all but surbodinate it to the other department. In this respect, it is required that a new hospital organization be made to acknowledge the independent function of the nursing department. In 76 per cent of the hospitals they have advisory committees under the nursing department, such as a dormitory self·regulating committee, an in-service education committee and a nursing procedure and policy committee. 9. Personnel arrangement and working conditions of nurses 1) The ratio of nurses to patients is as follows: In university hospitals, 1 to 2.9 for hospitalized patients and 1 to 4.0 for out-patients; in religious hospitals, 1 to 2.3 for hospitalized patients and 1 to 5.4 for out-patients. Grouped together this indicates that one nurse covers 2.2 hospitalized patients and 4.3 out-patients on a daily basis. The current medical treatment law stipulates that one nurse should care for 2.5 hospitalized patients or 30.0 out-patients. Therefore the statistics indicate that nursing services are being peformed with an insufficient number of nurses to cover out-patients. The current law concerns the minimum number of nurses and disregards the required number of nurses for operation rooms, recovery rooms, delivery rooms, new-born baby rooms, central supply rooms and emergency rooms. Accordingly, tile medical treatment law has been requested to be amended. 2) The ratio of doctors to nurses: In university hospitals, the ratio is 1 to 1.1; in national of public hospitals, 1 to 0.8; in religious hospitals 1 to 0.5; and in private hospitals 1 to 0.7. The average ratio is 1 to 0.8; generally the ideal ratio is 3 to 1. Since the number of doctors working in hospitals has been recently increasing, the nursing services have consequently teen overloaded, sacrificing the services to the patients. 3) The ratio of nurses to clerical staff is 1 to 0.4. However, the ideal ratio is 5 to 1, that is, 1 to 0.2. This means that clerical personnel far outnumber the nursing staff. 4) The ratio of nurses to nurse's-aides; The average 2.5 to 1 indicates that most of the nursing service are delegated to nurse's-aides owing to the shortage of registered nurses. This is the main cause of the deterioration in the quality of nursing services. It is a real problem in the guest for better nursing services that certain hospitals employ a disproportionate number of nurse's-aides in order to meet financial requirements. 5) As for the working conditions, most of hospitals employ a three-shift day with 8 hours of duty each. However, certain hospitals still use two shifts a day. 6) As for the working environment, most of the hospitals lack welfare and hygienic facilities. 7) The salary basis is the highest in the private university hospitals, with enterprise hospitals next and religious hospitals and national or public ones lowest. 8) Method of employment is made through paper screening, and further that the appointment of nurses is conditional upon the favorable opinion of the nursing directors. 9) The unemployment ratio for one year in 1971 averaged 29 per cent. The reasons for unemployment indicate that the highest is because of marriage up to 40 per cent, and next is because of overseas employment. This high unemployment ratio further causes the deterioration of efficiency in nursing services and supplementary activities. The hospital authorities concerned should take this matter into a jeep consideration in order to reduce unemployment. 10) The importance of in-service education is well recognized and established. 1% has been noted that on the-job nurses. training has been most active, with nursing directors taking charge of the orientation programs of newly employed nurses. However, it is most necessary that a comprehensive study be made of instructors, contents and methods of education with a separate section for in-service education. 10. Nursing services'activities 1) Division of services and job descriptions are urgently required. 81 per rent of the hospitals keep written regulations of services in accordance with nursing service manuals. 19 per cent of the hospitals do not keep written regulations. Most of hospitals delegate to the nursing directors or certain supervisors the power of stipulating service regulations. In 21 per cent of the total hospitals they have policy committees, standardization committees and advisory committees to proceed with the stipulation of regulations. 2) Approximately 81 per cent of the hospitals have service channels in which directors, supervisors, head nurses and staff nurses perform their appropriate services according to the service plans and make up the service reports. In approximately 19 per cent of the hospitals the staff perform their nursing services without utilizing the above channels. 3) In the performance of nursing services, a ward manual is considered the most important one to be utilized in about 32 percent of hospitals. 25 per cent of hospitals indicate they use a kardex; 17 per cent use ward-rounding, and others take advantage of work sheets or coordination with other departments through conferences. 4) In about 78 per cent of hospitals they have records which indicate the status of personnel, and in 22 per cent they have not. 5) It has been advised that morale among nurses may be increased, ensuring more efficient services, by their being able to exchange opinions and views with each other. 6) The satisfactory performance of nursing services rely on the following factors to the degree indicated: approximately 32 per cent to the systematic nursing activities and services; 27 per cent to the head nurses ability for nursing diagnosis; 22 per cent to an effective supervisory system; 16 per cent to the hospital facilities and proper supply, and 3 per cent to effective in·service education. This means that nurses, supervisors, head nurses and directors play the most important roles in the performance of nursing services. 11. About 87 per cent of the hospitals do not have separate budgets for their nursing departments, and only 13 per cent of the hospitals have separate budgets. It is recommended that the planning and execution of the nursing administration be delegated to the pertinent administrators in order to bring about improved proved performances and activities in nursing services.

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