• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.1
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• pp.2206-2217
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• 1971

Spillway and discharge channel of reservoirs require the Control of Large volume of water under high pressure. The energies at the downstream end of spillway or discharge channel are tremendous. Therefore, Some means of expending the energy of the high-velocity flow is required to prevent scour of the riverbed, minimize erosion, and prevent undermining structures or dam it self. This may be accomplished by Constructing an energy dissipator at the downstream end of spillway or discharge channel disigned to dissipated the excessive energy and establish safe flow Condition in the outlet channel. There are many types of energy dissipators, stilling basins are the most familar energy dissipator. In the stilling basin, most energies are dissipated by hydraulic jump. stilling basins have some length to cover hydraulic jump length. So stilling basins require much concrete works and high construction cost. Flip bucket type energy dissipators require less construction cost. If the streambed is composed of firm rock and it is certain that the scour will not progress upstream to the extent that the safety of the structure might be endangered, flip backet type energy dissipators are the most recommendable one. Following items are tested and studied with bucket radius, $R=7h_2$,(medium of $4h_2{\geqq}R{\geqq}10h_2$). 1. Allowable upstream channel slop of bucket. 2. Adequate bucket lip angle for good performance of flip bucket. Also followings are reviwed. 1. Scour by jet flow. 2. Negative pressure distribution and air movement below nappe flow. From the test and study, following results were obtained. 1. Upstream channel slope of bucket (S=H/L) should be 0.25<H/L<0.75 for good performance of flip bucket. 2. Adequated lip angle $30^{\circ}{\sim}40^{\circ}$ are more reliable than $20^{\circ}{\sim}30^{\circ}$ for the safety of structures.

• Journal of Gastric Cancer
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• v.8 no.1
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• pp.20-26
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• 2008

Purpose: Pylorus-preserving gastrectomy (PPG), which retains pyloric ring and gastric function, has been accepted as a function-preserving procedure for early gastric cancer for the prevention of postgastrectomy syndrome. This study was compared laparoscopy-assisted pylorus-preerving gastrectomy (LAPPG) with laparoscopy-assisted distal gastrectomy with Billroth-I reconstruction (LADGB I). Materials and Methods: Between November 2006 and September 2007, 39 patients with early gastric cancer underwent laparoscopy-assisted gastrectomy in the Department of Surgery at Korea Cancer Center Hospital. 9 of these patients underwent LAPPG and 18 underwent LADGBI. When LAPPG was underwent, we preserved the pyloric branch, hepatic branch, and celiac branch of the vagus nerve, the infrapyloric artery, and the right gastric artery and performed D1+$\beta$ lymphadenectomy to the exclusion of suprapyloric lymph node dissection. The distal stomach was resected while retaining a $2.5{\sim}3.0\;cm$ pyloric cuff and maintaining a $3.0{\sim}4.0\;cm$ distal margin for the resection. Results: The mean age for patients who underwent LAPPG and LADGBI were $59.9{\pm}9.4$ year-old and $64.1{\pm}10.0$ year-old, respectively. The sex ratio was 1.3 : 1.0 (male 5, female 4) in the LAPPG group and 2.6 : 1.0 (male 13, female 5) in the LADGBI group. Mean total number of dissected lymph nodes ($28.3{\pm}11.9$ versus $28.1{\pm}8.9$), operation time ($269.0{\pm}34.4$ versus $236.3{\pm}39.6$ minutes), estimated blood loss ($191.1{\pm}85.7$ versus $218.3{\pm}150.6\;ml$), time to first flatus ($3.6{\pm}0.9$ versus $3.5{\pm}0.8$ days), time to start of diet ($5.1{\pm}0.9$ versus $5.1{\pm}1.7$ days), and postoperative hospital stay ($10.1{\pm}4.0$ versus $9.2{\pm}3.0$ days) were not found significant differences (P>0.05). The postoperative complications were 1 patient with gastric stasis and 1 patient with wound seroma in LAPPG group and 1 patient with left lateral segment infarct of liver in the LADGB I group. Conclusion: Patients treated by LAPPG showed a comparable quality of surgical operation compared with those treated by LADGBI. LAPPG has an important role in the surgical management of early gastric cancer in terms of quality of postoperative life. Randomized controlled studies should be undertaken to analyze the optimal survival and long-term outcomes of this operative procedure.

• Journal of the Korean Society of Radiology
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• v.6 no.4
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• pp.281-290
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• 2012

The difference of radiation dose of MDCT due to different protocols between hospitals was analyzed by CTDI, DLP, the number of Slice and the number of DLP/Slice in 30 cases of the head, the abdomen and the chest that have 10 cases each from MDCT examination of the department of diagnostic imaging of three general hospitals in Gyeongsangbuk-do. The difference of image quality, CTDI, DLP, radiation dose in the eye and radiation dose in thyroid was analyzed after both helical scan and normal scan for head CT were performed because a protocol of head CT is relatively simple and head CT is the most frequent case. Head CT was significantly higher in two-thirds of hospitals compared to A hospital that does not exceed a CTDI diagnostic reference level (IAEA 50mGy, Korea 60mGy) (p<0.001). DLP was higher in one-third of hospitals than a diagnostic reference level of IAEA 1,050mGy.cm and Korea 1,000mGy.cm and two-thirds exceeded the recommendation of Korea and those were significantly higher than A hospital that does not exceed a diagnostic reference level (p<0.001). Abdomen CT showed 119mGy that was higher than a diagnostic reference level of IAEA 25mGy and Korea 20mGy in one-third. DLP in all hospitals was higher that Korea recommendation of 700mGy.cm. Among target hospitals, C hospital showed high radiation dose in all tests because MPR and 3D were of great importance due to low pitch and high Tube Curren. To analyze the difference of radiation dose by scan methods, normal scan and helical scan for head CT of the same patient were performed. In the result, CTDI and DLP of helical CT were higher 63.4% and 93.7% than normal scan (p<0.05, p<0.01). However, normal scan of radiation dose in thyroid was higher 87.26% (p<0.01). Beam of helical CT looked like a bell in the deep part and the marginal part so thyroid was exposed with low radiation dose deviated from central beam. In addition, helical scan used Gantry angle perpendicularly and normal scan used it parallel to the orbitomeatal line. Therefore, radiation dose in thyroid decreased in helical scan. However, a protocol in this study showed higher radiation dose than diagnostic reference level of KFDA. To obey the recommendation of KFDA, low Tube Curren and high pitch were demanded. In this study, the difference of image quality between normal scan and helical scan was not significant. Therefore, a standardized protocol of normal scan was generally used and protective gear for thyroid was needed except a special case. We studied a part of CT cases in the local area. Therefore, the result could not represent the entire cases. However, we confirmed that patient's radiation dose in some cases exceeded the recommendation and the deviation between hospitals was observed. To improve this issue, doctors of diagnostic imaging or technologists of radiology should perform CT by the optimized protocol to decrease a level of CT radiation and also reveal radiation dose for the right to know of patients. However, they had little understanding of the situation. Therefore, the effort of relevant agencies with education program for CT radiation dose, release of radiation dose from CT examination and addition of radiation dose control and open CT contents into evaluation for hospital services and certification, and also the effort of health professionals with the best protocol to realize optimized CT examination.