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Koichi Soga 대한소화기내시경학회 2024 Clinical Endoscopy Vol.57 No.2
Technical failure of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) is often attributed to device failure. To rectify this problem, we developed a single-pigtail plastic stent (SPPS) for EUS-GBD. We retrospectively reviewed the cases of four patients who underwent EUS-GBD for acute cholecystitis. To prepare the SPPS, a 7.5-Fr endoscopic nasobiliary drainage tube was cut to an appropriate length. The use of SPPS during EUS-GBD was successful from both technical and clinical standpoints. The SPPS spontaneously detached 57 days after the procedure in patient 4 and 412 days after the procedure in patient 1. Patient 1 developed cholecystitis after 426 days and was managed with antibiotics. The other three patients did not develop any complications after surgery. In conclusion, we designed a new SPPS dedicated to EUS-GBD and established its technical feasibility and clinical effectiveness.
Embodied Energy: Soil Retaining Geosystems
Kenichi Soga,Chris Chau,Duncan Nicholson,Heleni Pantelidou 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.4
Embodied energy is defined as the total energy in joules that can be attributed to bringing an item to its existing state. This paper attempts to quantify the amount of energy that is put into constructing geotechnical structures. In this study, several common retaining wall options are designed for (i) a hypothetical highway widening project based on a typical condition in London, (ii)basement construction of actual high rise buildings in London and (iii) embankments and cuttings as part of an actual highway road widening project. The embodied energy of each design was computed. Results show that the largest variance on embodied energy is the design solutions and within a given design the materials energy dominates over the installation energy and the transportation energy. The choice of Embodied Energy Intensity (EEI) of materials, particularly steel and concrete, is shown to have a large influence on the magnitude of embodied energy. When comparing among different designs of soil retaining structures, a recycled steel wall system generally has less embodied energy than the equivalent concrete wall system, which is more efficient than the equivalent virgin steel system. Results of the three case studies collectively indicate that minimizing materials usage is the key for reducing embodied energy in soil retention projects.
Factors affecting on leaching of lead from municipal solid waste incinerator residues
( Takaaki Soga ),( In-hee Hwang ),( Toshihiko Matsuto ),( Takayuki Matsuo ),( Yasumasa Tojo ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 한국폐기물자원순환학회 심포지움 Vol.2019 No.1
In Japan, about 80% of municipal waste is incinerated for volume reduction. Municipal solid waste incinerator (MSWI) residues contain heavy metals such as lead. Fly ash (FA) is classified as a hazardous waste which must be stabilized by treating chelating agent etc. prior to final disposal. On the other hand, bottom ash (BA) is classified to non-hazardous waste which is disposed in landfills directly. According to previous literature data, BA often release high concentration of Pb above regulatory criteria (0.3 mg/L) in Japanese leaching test No.13 (JLT-13). The aim of this research is to investigate those factors affecting on leaching of Pb from BA. BAs were obtained from twenty stoker type incinerators and two vertical type incinerators respectively. Five BAs were sampled before quenching in stocker type incinerators and the others are wet BAs sampled after quenching. JLT-13 and composition analysis were conducted for BA. JLT-13 was performed as follows: 45 g non-pretreated BA was mixed with 450ml distilled water (L/S ratio=10) in a glass flask, which was capped and shaken horizontally at 200 rpm for 6 h. The leachate was filtered through a 1μm membrane filter and filtrate was provided for measuring pH, metal and heavy metal concentrations, anion (Cl- and SO<sub>4</sub> <sup>2-</sup>) concentration, and TOC and IC concentrations. Before composition analysis, BA was pretreated as follows; BA was dried 60℃ for 2 days. Dried sample was pulverized for 3h in a ball mill and sieved through a 2 mm mesh. Pulverized BA was provided for measuring the contents of metal and heavy metals, ignition loss, TOC, and IC. In addition, the contents of calcium compounds (CaO, CaCO<sub>3</sub>, Ca(OH)<sub>2</sub>, etc.) and Fe<sub>2</sub>O<sub>3</sub> were analyzed by XRD. Figure 1 shows the relationship between Pb concentration and pH in filtrate. As Pb is amphoteric metal, it leaches in higher pH. Some filtrates show high Pb concentrations > 0.3mg/L, which are obtained from BAs before quenching. These contains more CaO compared to quenched BA. Figure 2 shows a positive correlation between pH and CaO content. Thus, CaO content of BA seems to make a difference in Pb concentration. Other factors such as IC, ion strength, etc. does not show obvious correlations with Pb concentration in filtrate. As already mentioned, BA before quenching showed higher Pb concentrations. To investigate the effect of quenching on Pb leaching concentration, lab-scale of quenching experiment was carried out using BA sampled before quenching process. BA was soaked in distilled water for 2.5 h and was dehydrated by gravity dewatering. Dehydrated sample was left for five days which was provided for JLT-13 and XRD analysis. Fig. 3 shows the variations of pH and Pb leaching concentration versus elapsed time. Pb leaching concentration gradually decreases with elapsed time. Ca concentration and pH decreased too. Figure 4 shows XRD peak of BA before and after quenching. High CaO peak exits in BA before quenching but it disappears after quenching and 5 days of exposure to the atmosphere. On the other hand, the peaks of Ca(OH)<sub>2</sub> and CaCO<sub>3</sub> appeared. Ca(OH)<sub>2</sub> is likely to be formed by hydration reaction of CaO in the procedure of quenching. CaCO<sub>3</sub> seems to be generated by the carbonation reaction of Ca(OH)<sub>2</sub> during exposure to the atmosphere. Those reactions lead to decrease of CaO which might bring about lower Pb release in JLT-13.
Koichi Soga 소화기인터벤션의학회 2021 Gastrointestinal Intervention Vol.10 No.3
A 65-year-old Japanese male presented with a substantial amount of bright red and burgundy rectal bleeding. A colonoscopy confirmed the presence of fresh blood and coagulation in the orifice of the appendix. A suitable position was found using an endoscopic hood to visualize the exposed vessel clearly. We placed two hemo-clips on the appendix orifice at opposite sides of the exposed vessel and then stirred them with an endoscopic hood to visualize the exposed vessel clearly. Finally, we placed other two hemo-clips near the exposed vessels and carried out a complete hemostasis with vessel thrombosis.