• 천문학회보
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• 제46권2호
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• pp.58.1-59
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• 2021

Exploration of asteroids' internal structure is essential for understanding their evolutional history. It also provides a fundamental information about the history of coalescence and collision of the solar system. Among several models of the internal structures, the rubble-pile model, confirmed by the near-Earth asteroid (25143) Itokawa by Hayabusa mission [1], is now widely regarded as the most common to asteroids with size ranging from 200 m to 10 km [2]. On the contrary, monolithic and core-mantle structures are also possible for small asteroids [3]. It is, however, still challenging to look through the interior of a target object using remote-sensing devices. In this presentation, we introduce our ongoing research conducted at Seoul National and propose an idea to infer the internal structure of Apophis using available instruments. Itokawa's research provides an important benchmark for Apophis exploration because both asteroids have similar size and composition [4][5]. We have conducted research on Itokawa's evolution in terms of collision and space weathering. Space weathering is the surface alteration process caused by solar wind implantation and micrometeorite bombardment [6]. Meanwhile, resurfacing via a collision acts as a counter-process of space weathering by exposing fresh materials under the matured layer and lower the overall degree of space weathering. Therefore, the balance of these two processes determine the space weathering degrees of the asteroid. We focus on the impact evidence on the boulder surface and found that space weathering progresses in only 100-10,000 years and modifies the surface optical properties (Jin & Ishiguro, KAS 2020 Fall Meeting). It is important to note that the timescale is significantly shorter than the Itokawa's age, suggesting that the asteroid can be totally processed by space weathering. Accordingly, our result triggers a further discussion about why Itokawa indicates a moderately fresh spectrum (Sq-type denotes less matured than S-type). For example, Itokawa's smooth terrains show a weaker degree of space weathering than other S-type asteroids [7]. We conjecture that the global seismic shaking caused by collisions with >1 mm-sized interplanetary dust particles induces granular convection, which hinders the progression of space weathering [8]. Note that the efficiency of seismic wave propagation is strongly dependent on the internal structure of the asteroid. Finally, we consider possible approaches to investigate Apophis's internal structure. The first idea is studying the space weathering age, as conducted for Itokawa. If Apophis indicates a younger age, the internal structure would have more voids [9]. In addition, the 2029 close encounter with Earth provides a rare natural opportunity to witness the contrast between before and after the event. If the asteroid exhibits a slight change in shape and space weathering degree, one can determine the physical structure of the internal materials (e.g., rubble-pile monolithic, thick or thin regolith layer, the cohesion of the materials). We will also consider a possible science using a seismometer.

• 실천공학교육논문지
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• 제15권1호
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• pp.209-221
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• 2023

반도체 제조 공정에서 사용되는 제품의 외관 검사 및 포장 단계에서 정전기에 의해 particle이 제품 자체나 운반용 도구 등에 흡착되는 문제가 발생한다. 본 연구는 실용 트리즈 기법을 활용하여 제품에 particle이 흡착되는 문제를 개선할 수 있는 방법론을 제시한다. 제시한 실용 트리즈 기반의 방법론을 적용하여 문제를 정의하고, 제품 대기 시간으로 인해 발생하는 모순을 도출하였다. 도출된 모순 중 물리적 모순을 설정하고 '공간분리'의 개념을 적용하여 '이오나이저 설치' 및 '작업실 Layout 개선'이라는 해결방안을 도출하였다. 실용 트리즈 적용을 통해 도출한 '이오나이저 설치' 및 '작업실 Layout 개선'을 적용하여 실험한 결과, 제품이 대기하는 시간에서 발생되는 particle 흡착 문제를 해결할 수 있음을 확인하였다. 본 연구를 통해, 제조현장에서 근무하는 작업자, 설비 엔지니어, 기술 엔지니어들이 실용 트리즈 기법을 활용하여 창의적 사고, 발상의 전환을 통해 직면한 문제를 효과적으로 해결하고 혁신적인 기술개발 및 생산성 향상에 기여할 수 있을 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.62-69
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• 2023

본 연구에서는 보수재료에 굵은 골재를 사용하게 되면서 얻을 수 있는 효과를 검토하기 위해 굵은 골재의 최대치수 및 조립률을 다양화 하면서 콘크리트의 특성을 파악하는 기초 연구를 수행하였다. 그 결과 콘크리트의 슬럼프는 굵은 골재 최대치수가 커질수록 증가하였고, 공기량은 최대 골재 치수가 10 mm 이상인 배합군에 비해 최대 골재 치수가 5 mm 의 골재를 사용한 배합에서 공기량이 1.88~2.35 배 높게 측정되었다. 압축강도는 굵은 골재의 실적률에 많은 영향을 받는 것으로 나타났다. 실적률이 가장 높은 최대치수 20 mm 의 굵은 골재를 사용한 배합에서 압축강도가 가장 높게 측정되었으며 실적률이 가장 낮은 배합의 압축강도보다 45% 이상 높게 나타났다. 건조수축 측정결과 굵은 골재 최대치수 및 조립률의 변화에 따라 굵은 골재의 실적률이 높아지면서 건조 수축이 가장 낮게 측정되었고, 실적률이 가장 낮은 배합에서 가장 크게 나타났다. 본 연구를 통해 콘크리트 구조물 보수용 재료에 사용되는 굵은 골재의 최대치수 및 조립률을 다양화해서 입도를 조정하게 되면 강도 및 작업성이 우수해지고 건조수축을 줄일 수 있는 것을 확인 할 수 있었다.

• 대한영상의학회지
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• 제84권2호
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• pp.477-482
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• 2023

매립혈액투석카테터 삽입을 위한 접근로 선택에서 쇄골하정맥은 이후에 동정맥루 접근로 형성을 위해 가능한 사용을 피하는 경로이다. 그러나 반복적 삽관으로 접근 가능한 정맥이 소진되거나 기대여명이 길지 않고 응급 투석이 필요한 경우 쇄골하정맥을 선택할 수 있다. 그러나 쇄골하정맥을 통한 혈액투석카테터 삽입에는 기술적인 어려움이 있다. 쇄골하정맥은 종종 상대정맥과 직각을 형성하여 굵은 혈관초삽입시 혈관 손상을 초래할 수 있다. 상지 거상 상태에서 혈관초를 삽입하는 방법은 각도를 완만하게 유도하여 이러한 문제를 극복하는데 도움을 줄 수 있다. 고식적앙와위 자세로 시술 중 상대정맥 손상이 있었던 환자와 연달아 내원하여 상지 거상 후 안전하게 혈액투석카테터를 삽입한 환자의 각각의 증례를 통해 상지 거상법이 도움이 될 수 있음을 보고하고자 한다.

• 대한간호학회지
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• 제4권3호
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• pp.63-79
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• 1974

1. The purpose of this study. The purpose of this study is to plan and investigate short-term nursing education of two-years associate degree program to produce middle-level professional nurses which are needed by-society and nation. Current nursing education in Korea is divided into four years degree program, three years diploma program Even (though) there are differences in the aims of their education, the curriculums are not much different between the education for producing leaders which is its basic purpose and training middle-level professional nurses. Therefore the purpose of associate degree program lies in minimizing the waste of time and finance which are invested for long-term education for middle-level professional nurses. And also this coincide with the policy of national technical training and definite supply of nurse manpower according to health policy for effective role and ability of nurse. 2. The method of study. This is based on the study of literature, research on the actual condition and investigation of opinion- through questionnaire. L) The study of literature: Domestic and foreign literatures for two years associate degree program were studied and investigated. 2) Research on the actual condition : Current three years nursing education program was collected and analysed. 3) Investigation of opinion. The problem of curried nursing education system and the possibility of two years associate degree program were investigated through questionnaire. 3. The result of the study. 1) The trend of recent nursing education. a. The aims of nursing in past chiefly taking care of physical disease of patient has recently changed to nursing of character including physical, mental, socio-economic, educational and psychological condition. b. For the performing systematic and effective nurse's duty according to her role, the-change of educational system which is classified as a range of education the period of education and certificate after graduation has been enforced or fulfilled. c. Nursing education also has a trend to become a collage or two years associate degree program which can get same legal protection as other educational institutions whose basic purpose is education. Attached nursing school to hospital is getting disappeared because of disadvantage of educational system. 2) Problems. Depending upon research on actual condition of current 3 years nursing education program. a. There are too many subjects. b. Contents of education could be doubled because major subjects are subdivided in detail. c. The credits for graduation are too heavy comparing to the period of study or the ability of students. (The necessary credits are 150.8 for three years according to actual investigation 4. There is no certain standard in organizing curriculum therefore there are too much differences between schools. 4. Basic Plan. The plan for two years associate degree program in nursing education depending on demand of professional nursing field of society is based on following items. 1) Training middle-level professional nurse lay emphasis on liberal arts and basic major field. 2) Liberal arts are divided into required and optional subjects and students could take courses by choice. 3) Major subjects are compound together by fields and they become the sciences of nursing Ⅰ,Ⅱ,Ⅲ,Ⅳ and every items has its educational purposes and contents major study includes laboratory practice and clinical experience. 4) The required credits for graduation are to which means 17-18 credits a semester. The above has been planned to solve the problems of current three years nursing education program. In conclusion for the achievement of this system, following items are needed. 1) It is necessary to change educational administration and system such as amendment of educational law or order of educational application of law. 2) Qualified professors should be available to understand and develope the idea or purpose of this educational system. 3) Local medical institutions should be opened widely and educational for clinical training. 4) The job after graduation should he secured positively.

• 한국조경학회지
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• 제43권6호
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• pp.150-159
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• 2015

본 연구는 우리나라의 대표적 아파트단지 조성 공공기관인 'J'공사를 대상으로 조경 식재 및 시설물 공종별 공사비 산정 비율 및 그들의 경년변화 특성 분석을 통해 향후 보다 합리적인 조경공사비 산정을 위한 기초 자료 제시를 목적으로 수행하였다. 연구의 대상 및 자료는 2004년부터 2012년까지 수행한 수도권 아파트단지 37개 현장의 조경식재 및 시설물 공사비를 대상으로 하였다. 경년변화 특성 분석을 위해 기술분석, 상관분석 등 통계분석 방법을 사용하였으며 다음과 같은 결론이 도출되었다. 첫째, 2004년부터 2012년까지 9년간 시행된 조경공사 비용 중 식재공사비와 시설물공사비의 평균 비율은 56.1% 대 43.9%인 것으로 나타났다. 둘째, 식재공사와 시설물공사 모두 약 ${\pm}3%$의 변동 폭에 국한되고 있어 물가상승률 등을 감안하며 거의 상대적 변화가 없는 특징을 보이고 있었다. 셋째, 조경공사 공종별 공사비 투입에서는 최소 ${\pm}1%$에서 최대 ${\pm}5%$의 변동폭(變動幅)을 보임으로써 조경공사비에서는 시설물공사비가 경년별 변화의 폭이 상대적으로 높은 특징을 보이는 것으로 나타났다. 넷째, 이상과 같이 경년별, 조경공종별 조경공사비의 비율이 일괄적으로 나타나는 것은 아파트단지의 지역적 특성과 입지여건 등의 조건을 반영하지 못하는 한계가 있었음을 알 수 있었다. 다섯째, 조경공종별 조경 요소별 상관관계가 높게 나타남으로써 전체적인 공사비 틀 안에서 공사비간의 부분적 조정을 통해 전체 조경공사비를 통제하고 있는 것으로 나타났다. 이상의 결과는 조경공사비가 이용자들의 만족이나, 아파트단지의 여건 등의 환경적 특성과 상관없이 획일적으로 책정되고 있다는 문제점을 제시하고 있었다.

• 대한방사선기술학회지:방사선기술과학
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• 제39권2호
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• pp.135-142
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• 2016

본 연구는 DR system에서 Chest PA 검사 시 일반적으로 적용되는 SID(180 cm)가 실제 심장크기 및 심흉비를 묘사하는데 적합한 거리인지 고찰해보고, 장비가 지닌 기하학적 원인이 영상에 미치는 영향을 알아보고자 한다. 자체 제작한 Chest phantom과 XGEO-GC80, INNOVISION-SH, UD150B-40 장비에 CXDI-40EG detector를 조합한 X선 발생장치를 이용하였다. 실험방법은 SID를 180 cm로 고정 후 OID를 0, 75, 83 mm로 변화시키며 영상을 획득하였다. 영상은 Centricity Radiography RA1000 PACS system에서 측정하였다. 통계프로그램은 SPSS(Version 22.0, SPSS, Chicago, IL, USA)를 사용하였고, p-value는 0.05 이하를 통계적으로 유의한 것으로 평가하였다. OID 0 mm에서 세 장비 모두 팬텀의 실제 CS, BS 보다 약 2.7~3.5 mm 정도 확대되었고, 계산된 확대율과 비교해 보았을 때 1.6~2.8% 확대되었다. OID 75 mm와 OID 83 mm에서는 6~8 mm 범위에서 CS와 BS가 확대되었다. 계산된 값과 비교했을 때 측정된 값은 6.1~7.9% 확대되었다. OID 변화에 따른 CS와 BS는 각 그룹간에 통계적으로 유의한 차이(p<0.05)를 보였으며, 사후분석에서는 OID 0 mm 그룹만 독립적인 그룹으로 나타났고, 75 mm와 83 mm는 동일한 그룹으로 분리되었다. 하지만 OID 변화에 따라서 통계적으로 유의한 차이가 없었으며(p >0.05), 사후 분석에서도 모두 같은 그룹으로 나타났다. DR system에서 Chest PA 검사 시 일반적으로 이용되고 있는 SID에서 검사하는 경우 심장의 크기는 실제 크기보다 6~8 mm크게 나타나며 이는 실제 이론적인 값보다 6.1~7.9% 확대되어 나타났다.

• KDI Journal of Economic Policy
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• 제13권2호
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• pp.69-96
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• 1991

1987년의 민주화조치(民主化措置) 이후 발생한 임금(賃金)의 급격한, 그리고 지속적인 상승은 비용우위(費用優位)의 약화를 야기하였고 이에 더하여 3저기간(低期間)의 무역수지흑자(貿易收支黑子)는 원화(貨)의 절상(切上)을 유발하여 우리 상품(商品)의 수출단가상승(輸出單價上昇)을 증폭시켰다. 새로운 경쟁우위(競爭優位)를 발굴하는 것이 우리 경제(經濟)의 당면과제(當面課題)인바 당분간은 비용우위유지(費用優位維持)가 우리 산업(産業)의 기본경쟁전략(基本競爭戰略)이 되어야 할 것이다. 이때의 비용우위(費用優位)는 기술(技術)의 뒷받침을 통하여 제품단가(製品單價)를 낮추는 것을 의미하며 이는 과거 저임금(低賃金)에 의존하던 비용우위유지(費用優位維持)와는 다른 것이다. 구체적(具體的) 방안(方案)의 하나로 기업간(企業間) 생산분업(生産分業)의 효율적(效率的) 조직화(組織化)를 생각해 볼 수 있다. 본(本) 연구(硏究)의 목적(目的)은 기업간(企業間) 생산분업(生産分業)으로서의 하도급(下都給)이 어떠한 형태(形態)로 운영되고 있는지 그리고 최근의 경제여건변화(經濟與件變化)에 대응하여 어떠한 방향(方向)으로 진전되고 있는지를 파악해 보는 데 있다. 구체적으로 모기업(母企業)과 수급기업간(受給企業間)의 교섭력(交涉力)의 차이, 수급기업(受給企業)의 모기업(母企業)에 대한 기술력(技術力)의 기여(寄與) 정도, 대외경쟁력(對外競爭力)의 약화(弱化)에 대응한 양자간(兩者間)의 협력관계(協力關係) 형성(形成), 새로운 경쟁우위(競爭優位)를 회복하기 위한 인식형성(認識形成)과 구체적 방안(方案)에 대한 견해(見解) 등을 하도급제(下都給制) 생산방식(生産方式)에 참여하고 있는 개별기업(個別企業)들에 대한 설문조사(設問調査)를 통하여 파악해 보고자 하였다. 설문조사(設問調査)의 결과(結果)에 따르면 자동차산업(自動車産業)의 하도급(下都給)이 경쟁력회복(競爭力回復)에 긍정적(肯定的)으로 작용(作用)하고 있는 것으로 나타났다.

• 한국문헌정보학회지
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• 제24권
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• pp.9-51
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• 1993

The purpose of this study is twofold: to investigate into general characteristics of the abstracting services in Korea and to discuss general directions of development of the abstracting services in the country. This study is designed to achieve the purpose by gathering and analysing data related to the abstracting journals published in the past ten years and by comparing the results with similar data gathered by the investigator in 1984. The major conclusions made in this study is summarised as follows. (1) Researchers and professionals working in limited numbers of subject fields are benefited by abstracting services of recent achievements in research and development in Korea. Those in most of the fields have essentially no abstracting services of such achievements. Even many researchers and professionals in the limited numbers of the fields that have some elementary abstracting services are not informed of research results in their fields because the abstracting journals are scattered in many narrow subjects and in many cases, the abstracting journals only cover publications in some specific forms and kinds. (2) Abstracting journals of general subjects, which are supposed to be of more or less help to the researchers in the subject fields that have no abstracting journals of their own, have rapidly increased in number in the past ten years. Most of such abstracting journals carry thesis and dissertation abstracts, and the rest those of research papers published in specific places, in specific forms, by specific institutes, and of reports of research projects sponsored by specific foundations. These abstracting journals are not of the kind that comprehensively provide general readers with current awareness of publications of research results in Korea. (3) Most of the abstracting journals existing in Korea are published by institutions of higher education and research institutes, and the rest by commercial publishers, industrial firms, libraries, information centers, government agencies, research foundations, learned societies, etc. Those which publish many titles are small in number and those publish one or two titles are large in number. The former is largely made up of institutions of higher education and research institutes. (4) Ten years ago, there was not a single publishing house that produced abstracting journals. Three commercial publishing houses now produce abstracting journals. As this change occurs, centers of excellence are founded and competitive elements are introduced in abstracting services. This change, in turn, is expected to improve quality of the other abstracting journals in Korea. (5) The abstracting journals published in Korea are classified by type into those of dissertations, research papers, journal articles, patent specifications in that descending order. The fact that Master's and doctoral dissertation abstracts are dominating in Korea is due to the irrational practice of publishing those abstracts at many institutions. (6) Most of the abstracting journals existing in Korea are published by national or government-supported research institutes in order to publicise their own research outputs. Their coverage of literature is normally narrow, and naturally their value to users is limited. (7) The abstracting journals published in Korea increased in number at the rate of $77.8-100\%$ every five years in the past twenty-five years. Most of the abstracting journals that ceased to be published during the period survived for two years. (8) Korean is the desirable language for the abstracting journals designed to be distributed within Korea. About half of the abstracting journals published in Korea is printed in Korean and the other half in foreign languages, and in Korean with foreign languages. All the abstracting journals in foreign languages are printed in English xcept one, which is printed in Japanese. (9) Some twenty percent of the abstracting journals in Korea is published monthly, bimonthly, and quarterly. Others are published annually, biannually, and irregularly. The latter may not function properly as a current-awareness tool due to long intervals between their issues. It is particularly undesirable that about half of the abstracting journals in Korea is published irregularly. Most of the abstracting journals published in Korea are distributed freely to individuals and institutions selected by the publishers. (10) The abstracting journals published by the use of computers increased drastically in the past ten years. The abstracting journals produced by the conventional type-setting method will probably disappear In Korea in another ten years to come. Automation of the production of abstracting journals does not simply mean technical, economic improvement of publishing processes but availability of machine-readable databases that can be used for other purposes, including the generation of other publications and the provision of machine literature searching capabilities. Necessary steps should be taken for this important development that is occurring in the abstracting services in Korea.

• Strategy21
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• 통권46호
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• pp.89-122
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• 2020

The longing for submarine manufacture and the fear of her power had exited for a long time, but submarine that could submerge and attack was built from 20th century by science technology development. The question, 'Submarine can exercise her power in naval warfare?' had exited before World War I, but the effective value of submarine was shown in the procedure of a chain of naval warfare during World War I and World War II. Germany and the United States made the best use of submarines at that time. The submarines of these nations mounted fierce attack on the enemy's battleships and merchant ships and blocked the sea lanes for war material. These fierce attack on ships became impossible After World War II, and the major powers reduced and coordinated the defence budget, so they considered the role of submarine. However, submarine is still powerful weapon system because she can secretly navigate under the water, and one of the most important force in the navy. The aim of this thesis is analyzing submarine roles in each naval warfare and integrating maritime strategy and weapon system technology into her roles. First, the research about represent submarine roles like anti-surfaceship warfare, anti-submarine warfare, intelligence gathering, land attack, supporting special operation and mine landing warfare will be presented, then the major naval warfare where submarine participated(during ex-World War I, World War I, World War II, The Cold War Era and post Cold War) and the analyzing of submarine roles by time will be presented. Submarine was developed for anti-surfaceship warfare during ex-World War I but could not make remarkable military gain in naval warfare because her performance and weapon was inadequate. However, the effective value of submarine in the procedure of a chain of naval warfare was shown during World War I and World War II. The major powers put battleships into naval warfare undiscriminatingly to command the sea power and submarines did massive damage to enemy navy power, so put a restraint the maritime power of enemy, and blocked the sea lanes for war material. After World War II, the battlefield situation changed rapidly and the concept of preemption became difficult to apply in naval warfare. Therefore, the submarine was unable to concentrate on anti-surfaceship mission. Especially during the Cold War era, nuclear submarine came to appear and her weapon system developed rapidly. These development gave submarines special missions: anti-submarine warfare and intelligence gathering. At that time, United States and Soviet submarines tracked other nation's submarines loaded with nuclear weapons and departing from naval their base. The submarines also collected information on the volume of ships and a coastal missile launching site in company with this mission. After Cold War, the major powers despatched forces to major troubled regions to maintain world peace, their submarines approached the shores of these regions and attacked key enemy installations with cruise missiles. At that time, the United States eased the concept of preemption and made the concept of Bush doctrine because of possible 911 terrorism. The missiles fired from submarines and surface battleships accurately attacked key enemy installations. Many nations be strategically successful depending on what kind of mission a submarine is assigned. The patterns of future naval warfare that my country will provide against will be military power projection and coalition/joint operations. These suggest much more about what future missions we should assign to submarines.