• 한국수학교육학회지시리즈E:수학교육논문집
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• 제35권2호
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• pp.173-191
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• 2021

본 연구는 국내 선행 연구에서 '팬데믹(pandemic)시기에 교사들을 대상으로 진행한 설문 조사 결과 원격수업 형식 중 '실시간 쌍방향 형' 수업이 차지하는 비중이 현저하게 적다는 점'을 지적한 것에 주목하여, 고등학교 수학 교과 기하 과목의 '평면의 결정 요건'을 중심으로 '실시간 쌍방향 형' 비대면 수업 자료를 개발하여 수업에 적용한 사례를 보고한 연구이다. 개발에 참여한 교사는 고등학교 교직 경력 28년차의 서울 소재 고등학교에 근무하는 수학 교사(수석교사) 1인이며, 2020년에 수학 교과의 기하 과목을 담당한 교사이다. 개발 교사는 실시간 쌍방향 형 비대면 수업을 개발하기로 한 이후, 수업 내용의 선정과 온라인 수업 도구를 선정하는 과정을 거친 다음 '만남 및 수업 안내', '동기 부여', '과제 제시', '개별 탐구 활동 및 교사 피드백', '성찰 및 평가'의 네 단계로 수업 지도안을 구성하여 자료를 개발하였다. 특히 '동기 부여' 과정에서는 개발 교사가 화이트보드 애니메이션 제작 프로그램인 Videoscribe를 이용해서 5분 정도의 영상 자료를 제작하여 제시하였으며, '과제제시'에서 과제 8번의 경우에는 학생들의 수업 종료 이후 자유로운 소감을 기록하는 것으로 구성하였는데, 이는 학생 스스로의 평가 장치임과 동시에 학생의 교사에 대한 피드백 제공 역할을 하였다. 본 연구는 현장 교사가 수업 자료를 개발하는 일련의 과정을 소개한 사례 연구로서, 수업에 바로 적용 가능한 수업 자료 제시와 더불어서 이후 수업 자료 개발에 대한 샘플 제시 역할에 목표를 두고 진행한 연구 결과물이다. 개발한 자료는 수업에 참여한 학생들의 의견 수렴 및 수학교사 3인에게 의뢰한 평가 결과를 바탕으로 수업 자료로서의 적합성 검증을 거쳤다.

• 공연문화연구
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• 제41호
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• pp.257-284
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• 2020

고성오광대는 1950년대 말부터 학술조사가 시작되어 1964년 국가무형문화재로 지정되었다. 지정 당시까지는 종이탈을 사용하였으나 1965년에는 이미 나무탈로 바뀌었으며 이후 탈의 변화 양상이 매우 크다. 1960년에는 9개의 탈을 사용하였는데 문둥이, 초란이, 말뚝이, 청보양반, 젓양반, 할미, 제밀주 탈을 기본으로 하였으며 여기에 소무는 제밀주와, 청보양반과 비비양반은 영감과 탈을 겸용하기도 하였다. 황봉사와 상주는 탈을 쓰지 않고 맨얼굴로 등장했다. 1965년부터 고성오광대 연희용 탈은 전체가 나무탈로 바뀌었다. 상주, 마당쇠, 상두꾼을 제외한 전 배역이 탈을 쓰고 있는데 비비, 홍백양반, 봉사 탈은 1964년까지는 등장한 적이 없는 탈이다. 초라니는 종가도령으로 바뀌었고 청보양반은 원양반으로 대체되었다. 1969년을 기점으로 연희용 탈은 종류가 현재와 같아지는 안정기에 들어선다. 비비양반과 소무를 제외한 모든 등장인물들이 개별탈을 사용하여 총18점의 탈을 사용한다. 양반들은 적제양반까지 확실하게 분화되어 총 7명의 양반이 등장한다. 이렇게 탈의 종류와 재질 및 표현법에 변화가 큰 것은 1세대 탈 제작자가 사망하면서 탈 제작의 전승이 끊어진 이유도 있겠으나 지정 이후 연희자들이 맞닥뜨려야 했던 연희환경의 극심한 변화에도 그 원인이 있다. 연희자들의 자족적인 놀이였기 때문에 세부 사항에서는 엄격한 규칙이 적용되지 않는 유동적인 놀이였으나 민속예술경연대회에 참가하면서 점차 공연을 위한 준비로 바뀌었다. 춤이나 의상, 소품들도 점차 화려해졌고 시각적인 효과와 짜임새 있는 연출을 시도하면서 연희 전반의 변화와 함께 탈의 변화를 가져왔고 이를 보존회 내부에서도 수용하게 되었다.

• 식물병연구
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• 제28권4호
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• pp.221-230
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• 2022

Erwinia amylovora에 의해 발생하는 화상병은 2015년에 국내에서 처음으로 보고된 이후 2021년 기준으로 전국 22개 지역으로 전파되었다. 우리나라는 식물방역법에 따라 화상병이 발생한 사과 및 배 과원은 발생주율을 기준으로 모든 기주식물들을 완전히 제거하여 구덩이에 매몰처리한다. 이후, 3년간 화상병균 전파를 막기 위해 매몰지 위에 기주식물 식재를 금하고 있다. 매몰처리법에 의한 화상병균 박멸 효과를 확인하기 위하여, 화상병 감수성 식물을 미끼식물로 이용하여 매몰지에 식재 후 화상병 재발 유무를 확인하였다. 이를 위해, 2019년부터 2021년에 매몰처리한 경기도 안성시와 충북 충주시 소재 매몰지 3곳을 선정하여 미끼식물 감시시설을 설치하였다. 화상병 감수성 식물인 사과(부사)를 미끼식물로 선정하고, 각 감시시설당 5주를 식재하였다. 감시시설은 울타리와 그물로 격리하였다. 또한, 실시간 모니터링을 위한 CCTV와 동작감지기, 그리고 현지 기상상황을 기록하는 센서를 설치하였다. 감시시설을 주기적으로 방문하여 육안으로 화상병 발병 유무를 확인하였다. 미끼식물로부터 화상병 의심 증상을 나타내는 표본을 채취하고 화상병균 특이적 프라이머를 이용하여 loop-mediated isothermal amplification polymerase chain reaction (PCR)과 conventional PCR을 통해 화상병균 감염 유무를 확인하였다. 그 결과, 현재까지 어떠한 미끼식물에서도 화상병균은 검출되지 않았다. 따라서, 현재 시행되고 있는 매몰 후 화상병 기주식물 3년 식재 금지 조항을 완화하는 근거로 본 연구 결과를 제시하고자 하며, 이를 통해 국내 과수산업과 농가의 피해를 최소화하는 데 기여할 수 있을 것이라 생각된다.

• 대한간호학회지
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• 제11권2호
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• pp.55-68
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• 1981

The prime object of the study is to evaluate how much all the students of the Nursing Schools throughout the nation are in comprehension toward the application of nursing process to clinical experience as means of systematic solution of nursing problems. An effort has been made to find out the actual state whether they are in practice of clinical experience in accordance with application of nursing process, over the period of four weeks managing from December 1st to 28th, 1980 and centering on 36 nursing schools, and meanwhile and evaluation, employing the assessment tool used by Bertuccietal, has been made on the nursing process notes recorded by 200 senions out of 21 nursing schools where application of nursing process to clinical experience being in practice. The assessment tool is composed of 5 different criteria in view of patient nursing and authors made an attempt to find out the result of clinical experience on application students in accordance with 5 different scoring criteria and further evaluating all the findings thereof. The findings were disposed of accordance with practice duration and criteria of the specific sudents subject to this finding as to verify the scoring difference in significance and of which the results are as follows: 1) as of now, in 21 (58.2%) out of 36 nursing Schools nursing process in being appliced in clinical experience. 2) Schools that started the application of nursing process to clinical experience amount to - for more than 4 yrs -6 (28.6％) - for 2 to 3 yrs-11s(52.4％) - for 1 yr -4 (19.0％) 3) As for the response upon application of nursing process. To clinical etperience, the largest voice (61.9%) heard was that it is rather difficult beyond the lecturing thereof, to practically apply it outs patients and the second voice (19.1%) turned out to be that it is hard to put in practice owing to uninformed nurses of the process serving in the clinical field. 4) The response. Of the processors assigned to instruction as to the most difficult problem in criteria of nursing process, the largest voice (38.2%) centered on the problem assessment while the second voice (17.7%) on the indirect nursing activity and the objective data respectively and considered to be the easiest was the indirect nursing activity (11.7%). 5) In order for a satisfactory. application of nursing process to clinical experience hence-forth, it has been pointed out that sufficient number of nurses should be supplemented in clinical field (44.1%) and at the same time supplementory education (35.3%) centered around professors be necessary. 6) Of the criteria that record result of nursing process, a significant difference in comprehension of subjective and objective data has been revealed according to the degree of the practice duration of application to clinical experience. For instance, while although poor it may seen, only 74.9% in subjective data and 71.1% in objective data represent the student group in practice for more than 4 years and only 56.3% in subjective data and 66.8% in objective data represent the student group in practice for 2 to 3 years but they still surpass in comprehension over the student group in practice for 1 year attaning only 19.6% in subjective data and 16.8% in objective data (P < 0.005). 7) As for problem assessment, the student group who started application of nursing process for 4 years stand for 37,7% the group for 2 to 3 years started for 25.3% and the group for 1 year started for 5.4%, revealing no significant difference according to duration (P < 0.5) and as poor as to indicate only 22.8% on an overage is in comprehension. 8) On direct and indirect nursing activity, the student group of for more than 4 years in appling nursing process (representing 49.5% in direct nursing activity, 21.4% in indirect nursing activity). Know more about it than the student group of for 2 to 3 years (representing 36.3% in direct nursing activity, 20.8% in indirect nursing activity) but revealed no significant difference. (P ＜ 0.5) 9) The student group applying nursing process for more than 4 years subjective data (74.9%) comprehend were more than objective data (71.1%) but shown no significant difference (P < 0.5). 10) However, the student group applying nursing process for 2 to 3 years comprehend objective data (66.8%) well ever subjective data (55.5%) indicating that 40.9% in average is in comprehension, thereby revealing a significant difference (P < 0.005). 11) On the other hand, the student group applying nursing process to clinical experience for 1 year had revealed themselves as poorly as to comprehend only 11.7% are an average of it, revealing no significant difference (P < 0.5). In consequence of the fore going, I the conductor of the present study, hereby suggest the following points: 1) Application of nursing process to clinical experience be practiced in all the Nursing Schools all over the nation at the earliest possible date in order that scientific nursing be prevailed (as of now only 58.0%), 2) In teaching nursing process, it is desirable to teach specific method of applying to practical clinical situations. 3) In order to meet the end of satisfactory application of nursing process to clinical experience, sufgecient nursing man power be sysplemented in clinical field and at the save time supplementary education by professors is necessary. 4) Sinces the students whose application duration of nursing process to clinical experience is longer comprehend more about it, it is reguired that the schools not yet in practice of the application be promptlyurged to follow. 5) Of the criteria recording nursing process, since it is comparatively hard to comprehend“assessment”and“Direct and indirect nursing activity”, a concentrated instruction is desirable. 6) The students whose duration of application of nursing process to clinical experience falls short of 1 years be put in a concentrated guidance program on individual criterion.

• 화약ㆍ발파
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• 제9권1호
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• pp.3-13
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• 1991

발파에 의한 지반진동의 크기는 화약류의 종류에 따른 화약의 특성, 장약량, 기폭방법, 전새의 상태와 화약의 장전밀도, 자유면의 수, 폭원과 측간의 거리 및 지질조건 등에 따라 다르지만 지질 및 발파조건이 동일한 경우 특히 측점으로부터 발파지점 까지의 거리와 지발당 최대장약량 (W)간에 깊은 함수관계가 있음이 밝혀졌다. 즉 발파진동식은 $V=K{\cdot}(\frac{D}{W^b})^n{\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$ (1) 여기서 V ; 진동속도, cm /sec D ; 폭원으로부터의 거리, m W ; 지발 장약량, kg K ; 발파진동 상수 b ; 장약지수 R ; 감쇠지수 이 발파진동식에서 b=1/2인 경우 즉 $D{\;}/{\;}\sqrt{W}$를 자승근 환산거리(Root scaled distance), $b=\frac{1}{3}$인 경우 즉 $D{\;}/{\;}\sqrt[3]{W}$를 입방근환산거리(Cube root scaled distance)라 한다. 이 장약 및 감쇠지수와 발파진동 상수를 구하기 위하여 임의거리와 장약량에 대한 진동치를 측정, 중회귀분석(Multiple regressional analysis)에 의해 일반식을 유도하고 Root scaling과 Cube root scaling에 대한 회귀선(regression line)을 구하여 회귀선에 대한 적합도가 높은 쪽을 택하여 비교, 검토하였다. 위 (1)식의 양변에 log를 취하여 linear form(직선형)으로 바꾸어 쓰면 (2)式과 같다. log V=A+BlogD+ClogW ----- (2) 여기서, A=log K B=-n C=bn (2)식은 다시 (3)식으로 표시할 수 있다. $Yi=A+BXi_{1}+CXi_{2}+{\varepsilon}i{\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$(3) 여기서, $Xi_{1},{\;}Xi_{2} ;(두 독립변수 logD, logW의 i번째 측정치. Yi ; ($Xi_1,{\;}Xi_2$)에 대한 logV의 측정치 ${\varepsilon}i$ ; error term 이다. (3)식에서 n개의 자료를 (2)식의 회귀평면으로 대표시키기 위해서는 $S={\sum}^n_{i=1}\{Yi-(A+BXi_{1}+CXi_{2})\}\^2$을 최소로하는 A, B, C 값을 구하면 된다. 이 방법을 최소자승법이 라 하며 S를 최소로 하는 A, B, C의 값은 (4)식으로 표시한다. $\frac{{\partial}S}{{\partial}A}=0,{\;}\frac{{\partial}S}{{\partial}B}=0,{\;}\frac{{\partial}S}{{\partial}C}=0{\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$ (4) 위식을 Matrix form으로 간단히 나타내면 식(5)와 같다. [equation omitted] (5) 자료가 많아 계산과정이 복잡해져서 본실험의 정자료들은 전산기를 사용하여 처리하였다. root scaling과 Cube root scaling의 경우 각각 $logV=A+B(logD-\frac{1}{2}W){\;}logV=A+B(logD-\frac{1}{3}W){\;}\}{\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$ (6) 으로 (2)식의 특별한 형태이며 log-log 좌표에서 직선으로 표시되고 이때 A는 절편, B는 기울기를 나타낸다. $\bullet$ 측정치의 검토 본 자료의 특성을 비교, 검토하기 위하여 지금까지 발표된 국내의 몇몇 자료를 보면 다음과 같다. 물론, 장약량, 폭원으로 부터의 거리등이 상이하지만 대체적인 경향성을 추정하는데 참고할수 있을 것이다. 금반 총실측자료는 총 88개이지만 환산거리(5.D)와 진동속도의 크기와의 관계에서 차이를 보이고 있어 편선상 폭원과 측점지점간의 거리에 따라 l00m말만인 A지역과 l00m이상인B지역으로 구분하였다. 한편 A지역의 자료 56개중, 상하로 편차가 큰 19개를 제외한 37개자료와 B지역의 29개중 2개를 낙외한 27개(88개 자료중 거리표시가 안된 12월 1일의 자료3개는 원래부터 제외)의 자료를 computer로 처리하여 얻은 발파진동식은 다음과 같다. $V=41(D{\;}/{\;}\sqrt[3]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$ (7) (-100m)(R=0.69) $V=124(D{\;}/{\;}\sqrt[3]{W})^{-1.66){\;}{\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots}$ (8) (+100m)(R=0.782) 식(7) 및 (8)에서 R은 구한 직선식의 적합도를 나타내는 상관계수로 R=1인때는 모든 측정자료가 하나의 직선상에 표시됨을 의미하며 그 값이 낮을수록 자료가 분산됨을 뜻한다. 본 보고에서는 상관계수가 자승근거리때 보다는 입방근일때가 더 높기 때문에 발파진동식을 입방근($D{\;}/{\;}\sqrt[3]{W}$)으로 표시하였다. 특히 A지역에서는 R=0.69인데 비하여 폭원과 측점지점간의 거리가 l00m 이상으로 A지역보다 멀리 떨어진 B지역에서는 R=0.782로 비교적 높은 값을 보이는 것은 진동성분중 고주파성분의 상당량이 감쇠를 당하기 때문으로 생각된다.

• 한국과학교육학회지
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• 제16권4호
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• pp.376-388
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• 1996

The first and the second "Discussion Contest of Scientific Investigation" was evaluated in this study. This contest was a part of 'Korean Youth Science Festival' held in 1993 and 1994. The evaluation was based on the data collected from the middle school students of final teams, their teachers, a large number of middle school students and college students who were audience of the final competition. Questionnaires, interviews, reports of final teams, and video tape of final competition were used to collect data. The study focussed on three research questions. The first was about the preparation and the research process of students of final teams. The second was about the format and the proceeding of the Contest. The third was whether participating the Contest was useful experience for the students and the teachers of the final teams. The first area, the preparation and the research process of students, were investigated in three aspects. One was the level of cooperation, participation, support and the role of teachers. The second was the information search and experiment, and the third was the report writing. The students of the final teams from both years, had positive opinion about the cooperation, students' active involvement, and support from family and school. Students considered their teachers to be a guide or a counsellor, showing their level of active participation. On the other hand, the interview of 1993 participants showed that there were times that teachers took strong leading role. Therefore one can conclude that students took active roles most of the time while the room for improvement still exists. To search the information they need during the period of the preparation, student visited various places such as libraries, bookstores, universities, and research institutes. Their search was not limited to reading the books, although the books were primary source of information. Students also learned how to organize the information they found and considered leaning of organizing skill useful and fun. Variety of experiments was an important part of preparation and students had positive opinion about it. Understanding related theory was considered most difficult and important, while designing and building proper equipments was considered difficult but not important. This reflects the students' school experience where the equipments were all set in advance and students were asked to confirm the theories presented in the previous class hours. About the reports recording the research process, students recognize the importance and the necessity of the report but had difficulty in writing it. Their reports showed tendency to list everything they did without clear connection to the problem to be solved. Most of the reports did not record the references and some of them confused report writing with story telling. Therefore most of them need training in writing the reports. It is also desirable to describe the process of student learning when theory or mathematics that are beyond the level of middle school curriculum were used because it is part of their investigation. The second area of evaluation was about the format and the proceeding of the Contest, the problems given to students, and the process of student discussion. The format of the Contests, which consisted of four parts, presentation, refutation, debate and review, received good evaluation from students because it made students think more and gave more difficult time but was meaningful and helped to remember longer time according to students. On the other hand, students said the time given to each part of the contest was too short. The problems given to students were short and open ended to stimulate students' imagination and to offer various possible routes to the solution. This type of problem was very unfamiliar and gave a lot of difficulty to students. Student had positive opinion about the research process they experienced but did not recognize the fact that such a process was possible because of the oneness of the task. The level of the problems was rated as too difficult by teachers and college students but as appropriate by the middle school students in audience and participating students. This suggests that it is possible for student to convert the problems to be challengeable and intellectually satisfactory appropriate for their level of understanding even when the problems were difficult for middle school students. During the process of student discussion, a few problems were observed. Some problems were related to the technics of the discussion, such as inappropriate behavior for the role he/she was taking, mismatching answers to the questions. Some problems were related to thinking. For example, students thinking was off balanced toward deductive reasoning, and reasoning based on experimental data was weak. The last area of evaluation was the effect of the Contest. It was measured through the change of the attitude toward science and science classes, and willingness to attend the next Contest. According to the result of the questionnaire, no meaningful change in attitude was observed. However, through the interview several students were observed to have significant positive change in attitude while no student with negative change was observed. Most of the students participated in Contest said they would participate again or recommend their friend to participate. Most of the teachers agreed that the Contest should continue and they would recommend their colleagues or students to participate. As described above, the "Discussion Contest of Scientific Investigation", which was developed and tried as a new science contest, had positive response from participating students and teachers, and the audience. Two among the list of results especially demonstrated that the goal of the Contest, "active and cooperative science learning experience", was reached. One is the fact that students recognized the experience of cooperation, discussion, information search, variety of experiments to be fun and valuable. The other is the fact that the students recognized the format of the contest consisting of presentation, refutation, discussion and review, required more thinking and was challenging, but was more meaningful. Despite a few problems such as, unfamiliarity with the technics of discussion, weakness in inductive and/or experiment based reasoning, and difficulty in report writing, The Contest demonstrated the possibility of new science learning environment and science contest by offering the chance to challenge open tasks by utilizing student science knowledge and ability to inquire and to discuss rationally and critically with other students.

• 한국농공학회지
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• 제7권1호
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• pp.861-876
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• 1965

During my stay in the Netherlands, I have studied the following, primarily in relation to the Mokpo Yong-san project which had been studied by the NEDECO for a feasibility report. 1. Unit hydrograph at Naju There are many ways to make unit hydrograph, but I want explain here to make unit hydrograph from the- actual run of curve at Naju. A discharge curve made from one rain storm depends on rainfall intensity per houre After finriing hydrograph every two hours, we will get two-hour unit hydrograph to devide each ordinate of the two-hour hydrograph by the rainfall intensity. I have used one storm from June 24 to June 26, 1963, recording a rainfall intensity of average 9. 4 mm per hour for 12 hours. If several rain gage stations had already been established in the catchment area. above Naju prior to this storm, I could have gathered accurate data on rainfall intensity throughout the catchment area. As it was, I used I the automatic rain gage record of the Mokpo I moteorological station to determine the rainfall lntensity. In order. to develop the unit ~Ydrograph at Naju, I subtracted the basic flow from the total runoff flow. I also tried to keed the difference between the calculated discharge amount and the measured discharge less than 1O~ The discharge period. of an unit graph depends on the length of the catchment area. 2. Determination of sluice dimension Acoording to principles of design presently used in our country, a one-day storm with a frequency of 20 years must be discharged in 8 hours. These design criteria are not adequate, and several dams have washed out in the past years. The design of the spillway and sluice dimensions must be based on the maximun peak discharge flowing into the reservoir to avoid crop and structure damages. The total flow into the reservoir is the summation of flow described by the Mokpo hydrograph, the basic flow from all the catchment areas and the rainfall on the reservoir area. To calculate the amount of water discharged through the sluiceCper half hour), the average head during that interval must be known. This can be calculated from the known water level outside the sluiceCdetermined by the tide) and from an estimated water level inside the reservoir at the end of each time interval. The total amount of water discharged through the sluice can be calculated from this average head, the time interval and the cross-sectional area of' the sluice. From the inflow into the .reservoir and the outflow through the sluice gates I calculated the change in the volume of water stored in the reservoir at half-hour intervals. From the stored volume of water and the known storage capacity of the reservoir, I was able to calculate the water level in the reservoir. The Calculated water level in the reservoir must be the same as the estimated water level. Mean stand tide will be adequate to use for determining the sluice dimension because spring tide is worse case and neap tide is best condition for the I result of the calculatio 3. Tidal computation for determination of the closure curve. During the construction of a dam, whether by building up of a succession of horizontael layers or by building in from both sides, the velocity of the water flowinii through the closing gapwill increase, because of the gradual decrease in the cross sectional area of the gap. 1 calculated the . velocities in the closing gap during flood and ebb for the first mentioned method of construction until the cross-sectional area has been reduced to about 25% of the original area, the change in tidal movement within the reservoir being negligible. Up to that point, the increase of the velocity is more or less hyperbolic. During the closing of the last 25 % of the gap, less water can flow out of the reservoir. This causes a rise of the mean water level of the reservoir. The difference in hydraulic head is then no longer negligible and must be taken into account. When, during the course of construction. the submerged weir become a free weir the critical flow occurs. The critical flow is that point, during either ebb or flood, at which the velocity reaches a maximum. When the dam is raised further. the velocity decreases because of the decrease\ulcorner in the height of the water above the weir. The calculation of the currents and velocities for a stage in the closure of the final gap is done in the following manner; Using an average tide with a neglible daily quantity, I estimated the water level on the pustream side of. the dam (inner water level). I determined the current through the gap for each hour by multiplying the storage area by the increment of the rise in water level. The velocity at a given moment can be determined from the calcalated current in m3/sec, and the cross-sectional area at that moment. At the same time from the difference between inner water level and tidal level (outer water level) the velocity can be calculated with the formula $h= \frac{V^2}{2g}$ and must be equal to the velocity detertnined from the current. If there is a difference in velocity, a new estimate of the inner water level must be made and entire procedure should be repeated. When the higher water level is equal to or more than 2/3 times the difference between the lower water level and the crest of the dam, we speak of a "free weir." The flow over the weir is then dependent upon the higher water level and not on the difference between high and low water levels. When the weir is "submerged", that is, the higher water level is less than 2/3 times the difference between the lower water and the crest of the dam, the difference between the high and low levels being decisive. The free weir normally occurs first during ebb, and is due to. the fact that mean level in the estuary is higher than the mean level of . the tide in building dams with barges the maximum velocity in the closing gap may not be more than 3m/sec. As the maximum velocities are higher than this limit we must use other construction methods in closing the gap. This can be done by dump-cars from each side or by using a cable way.e or by using a cable way.