The safety of shore structure including the sea dipe is largely affected by typhoon. Accordingly it is desirable to analize the typhoon and determine the wind direction and velocity for use in planning and design of the structure. This method was adopted for the design of the Yong San Gang Estuary Dam. A comparative study of the results of typhoon analysis with the meteorological data obtained through actual observation is summarized as follows; (1) 62% of the typhoons occur during May to June in a year, and 62% of the typhoons which have an influence on the Korean peninsula, especially the proposed estuary dam fsite, proceed eastward through the zone in lat. 36$^{\circ}$-37$^{\circ}$N. Such typhoons occur two to three times a year on the average. (2) Data on typhoon "SARL" were used as a model case in designing the estuary dam, where it was proved that a southwesterly wind had a maximum velocity of 30m/sec in case r=150km, ${\alpha}$=120$^{\circ}$. Within the range of 22$^{\circ}$30'on the right and left side of the fetch line of the estuary dam, the wind direction varied SSW\longrightarrowSW\longrightarrowWSW, and the wind velocity varied 29m/sec\longrightarrow30m/sec\longrightarrow125m/sec. Such phenomemum lasted for five hours. (3) An analysis of data obtained during 44 years at Mok Po Meteorological Station shows that a wind with a velocity of some 25m/sec occurred twelve times in the S-direction and two times in the SW-direction, while that with a velocity of 30m/sec occurred three times in the S-direction, three times in the SSW-direction and one time in the SW-direction. The wind which had an influence on the estuary dam had a direction of SSW\longrightarrowSW\longrightarrowWSW and a velocity of min. 30m/sec. Actually, a wind with a max. velocity of 31.3m/sec occurred in the SSW-direction on March 15 and 16, 1956 where the mean velocity during two hours was 28m/sec and that during four hours was 24.6m/sec. (4) The data obtained through actual observation show that when the velocity is low, the wind with a fixed direction lasts long, and when the velocity is high, it is short-lived. It is difficult to determine the velocity of a wind which blows in a fixed direction for consecutive two or four hours. Therefore, the values obtained through typhoon analysis are larger that those obtained through actual observation, and hence, it is resonable to use the analyzed valuse for design of the estuary dam and shore structures. (5) The greatest effect was had on the estuary dam when typhoon was proceeding at a velocity of 29.71m/sec in the direction of ${\alpha}$=120$^{\circ}$(SW) at a point of R=150km from the center of the typhoon.

This experiment was carried out to investigate the efficient turning method which will be able to use every cutting methods, to calculate the width of the center field which must transpose from rotary cutting method to return cutting method, to investigate the effects of L/W and unit field on the operation efficiency. The results are summarized as follows: 1. In case of cutting in the outer field, the efficient turning method is the "$\alpha$" type turning method (half U-shaped turning method) at the first rotation, is the "$\beta$" type turning method (T-shaped turning method) at the second to fourth rotation. 2. In case of cutting in the inner field, the efficient turning method which takes the least turning time is the "a" type turning method ($\Delta$-shaped turning method). 3. The width of the center field (W') changes by the length-width ratio (L/W) and width (W), W' is 9.0m in case that L/W is 2.5 and W is 30m. 4. The larger L/W and area of unit field (A) become, the more operation efficiency (E) increases, and the limits that E is affected signicantly by L/W is 2 to 3.5 and A is within 5,000$m^2$. within 5,000$m^2$.

With the use of many rivers increased nearly to the capacity, the need for information concerning daily quantities of water and the total annual or seasonal runoff has became increased. A systematic record of the flow of a river is commonly made in terms of the mean daily discharge Since. a single observation of stage is converted into discharge by means of rating curve, it is essential that the stage discharge relations shall be accurately established. All rating curves have the looping effect due chiefly to channel storage and variation in surface slope. Loop rating curves are most characteristic on streams with somewhat flatter gradients and more constricted channels. The great majority of gauge readings are taken by unskilled observers once a day without any indication of whether the stage is rising or falling. Therefore, normal rating curves shall show one discharge for one gauge height, regardless of falling or rising stage. The above reasons call for the correction of the discharge measurements taken on either side of flood waves to the theoretical steady-state condition. The correction of the discharge measurement is to consider channel storage and variation in surface slope. (1) Channel storage As the surface elevation of a river rises, water is temporarily stored in the river channel. There fore, the actual discharge at the control section can be attained by substracting the rate of change of storage from the measured discharge. (2) Variation in surface slope From the Manning equation, the steady state discharge Q in a channel of given roughness and cross-section, is given as {{{{Q PROPTO SQRT { 1} }}}} When the slope is not equal, the actual discharge will be {{{{ { Q}_{r CDOT f } PROPTO SQRT { 1 +- TRIANGLE I} CDOT TRIANGLE I }}}} may be expressed in the form of {{{{ TRIANGLE I= { dh/dt} over {c } }}}} and the celerity is approximately equal to 1.3 times the mean watrr velocity. Therefore, The steady-state discharge can be estimated from the following equation. {{{{Q= { { Q}_{r CDOT f } } over { SQRT { (1 +- { A CDOT dh/dt} over {1.3 { Q}_{r CDOT f }I } )} } }}}} If a sufficient number of observations are available, an alternative procedure can be applied. A rating curve may be drawn as a median line through the uncorrected values. The values of {{{{ { 1} over {cI } }}}} can be yielded from the measured quantities of Qr$.$f and dh/dt by use of Eq. (7) and (8). From the 1/cI v. stage relationship, new vlues of 1/cI are obtained and inserted in Eq. (7) and (8) to yield the steady-state discharge Q. The new values of Q are then plotted against stage as the corrected steadystate curve.