• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.378-387
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• 2023

Petrochemical is an energy consuming industry that consumes about 30% of total industrial energy consumption and is a representative carbon dioxide (CO₂) emission source. Among them, the Naphtha Cracking Center (NCC), which produces ethylene, propylene, propane and mixed C4, consumes large amounts of energy and emits significant amounts of CO₂. For this reason, an integrated techno economic- environmental impact assessment aimed at reducing energy consumption and environmental impact factors is necessary to ensure efficiency in terms of economics and environment. This study aims to analyze the efficiency of the heat exchanger network used in the existing NCC base on the pinch analysis and select an improvement plan that can reduced energy consumption. In order to reduces the utility consumption in the process, an optimal heat exchanger network considering the high-temperature and low-temperature stream was derived, and the economic evaluation was conducted by considering the trade-off between the reduction in utility consumption and the increase in heat exchanger installation cost. In addition, an environmental impact assessment was conducted on the reduced CO₂ emission in consideration of the environmental aspect, and the economic environmental impact assessment used the payback period to recover the invested funds to come up with an energy saving plan that can be applied based on the actual process. As a result of considering the economic-environmental impact assessment, when the environmental impact assessment was not considered, it was 4.29 months, 3.21 months, and 3.39 months for each case, and when considering the environmental impact assessment, it was 4.24 months, 3.17 months, and 3.35 months for each case. These results appeared equally both when the environmental impact assessment was not include and when it was include. In addition, a sensitivity analysis was conducted for each case to determine how important factors affect the payback period. As a result of the sensitivity analysis, the cost of the heat exchanger was identified as a major factor influencing the overall cost.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.201-209
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• 2010

Generally, PSC girder bridge uses total gross cross section to resist applied loads unlike reinforced concrete member. Also, it is used as short and middle span (less than 30 m) bridges due to advantages such as ease of design and construction, reduction of cost, and convenience of maintenance. But, due to recent increased public interests for environmental friendly and appearance appealing bridges all over the world, the demands for longer span bridges have been continuously increasing. This trend is shown not only in ordinary long span bridge types such as cable supported bridges but also in PSC girder bridges. In order to meet the increasing demands for new type of long span bridges, PSC hollow box girder with H-type steel as compression reinforcements is developed for bridge with a single span of more than 50 m. The developed PSC girder applies compressive prestressing at H-type compression reinforcements using unbonded PS tendon. The purpose of compressive prestressing is to recover plastic displacement of PSC girder after long term service by releasing the prestressing. The static test composed of 4 different stages in 3-point bending test is performed to verify safety of the bridge. First stage loading is applied until tensile cracks form. Then in second stage, the load is removed and the girder is unloaded. In third stage, after removal of loading, recovery of remaining plastic deformation is verified as the compressive prestressing is removed at H-type reinforcements. Then, in fourth stage, loading is continued until the girder fails. The experimental results showed that the first crack occurs at 1,615 kN with a corresponding displacement of 187.0 mm. The introduction of the additional compressive stress in the lower part of the girder from the removal of unbonded compressive prestressing of the H-type steel showed a capacity improvement of about 60% (7.7 mm) recovery of the residual deformation (18.7 mm) that occurred from load increase. By using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and rehabilitation of PSC girders are relatively easy, and the cost of maintenance is expected to decrease.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.132-158
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• 2023

The five-story and seven-story stone pagodas at Cheongnyangsaji temple site in Gongju are located under the Sambulbong peak of Gyeryongsan mountain, and are known to have been built of the middle in Goryeo dynasty. As the two pagodas in which two types of Baekje stone pagoda coexist in one era, their historical and academic value are recognized. The seven-story pagoda was overturned by robbery in 1944, and as a result, the five-story pagoda was tilted. Although the two pagodas were restored in 1961, structural instability was continuously raised. In this study, measurement data accumulated from May 2021 to March 2022, and seasonal characteristics were reviewed, and the micro behavior of pagodas were analyzed according to temperature and precipitation during the same period. As a result, the micro thermoelastic behavior was repeated according to the daily temperature change in all sensors, and both the slope and the displacement showed microscale behavior. In the inclinometer, moisture containing the surface and inside of the stones repeated expansion and contraction due to temperature change, showing the micro movements. In particular, the upper part of the five-story pagoda moved up to 3.89° to the northwest, and the seven-story pagoda tilted up to 0.078° to the northeast. The maximum displacements were recorded as 0.127 and 0.149 mm in the five-story and the seven-story pagoda, respectively. These values tended to return to the original position at the end of the measurement, but did not recover completely, indicating a state requiring precise monitoring. The result obtained through the study can be used as basic data for the stable conservation of the two stone pagodas. Based on the behavioral characteristics considering various environmental factors should be analyzed, and the preventive conservation through the maintenance of measurement system built this time should be continued.

• IMMUNE NETWORK
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• v.24 no.2
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• pp.7.1-7.19
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• 2024

Viral load and the duration of viral shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are important determinants of the transmission of coronavirus disease 2019. In this study, we examined the effects of viral doses on the lung and spleen of K18-hACE2 transgenic mice by temporal histological and transcriptional analyses. Approximately, 1×10⁵ plaque-forming units (PFU) of SARS-CoV-2 induced strong host responses in the lungs from 2 days post inoculation (dpi) which did not recover until the mice died, whereas responses to the virus were obvious at 5 days, recovering to the basal state by 14 dpi at 1×10² PFU. Further, flow cytometry showed that number of CD8+ T cells continuously increased in 1×10² PFU-virus-infected lungs from 2 dpi, but not in 1×10⁵ PFU-virus-infected lungs. In spleens, responses to the virus were prominent from 2 dpi, and number of B cells was significantly decreased at 1×10⁵ PFU; however, 1×1² PFU of virus induced very weak responses from 2 dpi which recovered by 10 dpi. Although the defense responses returned to normal and the mice survived, lung histology showed evidence of fibrosis, suggesting sequelae of SARS-CoV-2 infection. Our findings indicate that specific effectors of the immune response in the lung and spleen were either increased or depleted in response to doses of SARS-CoV-2. This study demonstrated that the response of local and systemic immune effectors to a viral infection varies with viral dose, which either exacerbates the severity of the infection or accelerates its elimination.

• Journal of the Korean Applied Science and Technology
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• v.40 no.6
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• pp.1309-1321
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• 2023

This study was conducted by dividing L-arginine intake group (n=14) and placebo group (n=14) to investigate the effect of L-arginine intake on athletic performance, lactate, lactate dehydrogenase, and ammonia of men's college Taekwondo Kyorugi players during 8-week of intensive winter training. The L-arginine intake group consumed a total of 3 g, including 1 g for breakfast, 1 g for lunch, and 1 g for dinner, and the placebo group consumed maltodextrin in the same way. The 8-week winter training program was conducted at 70-90%HRR (heart rate reserve). Two-way repeated measures ANOVA was used for the interaction between the L-arginine intake group and the placebo group of the measured data, paired t-test was used for the difference between the periods within the group, and the difference between groups was analyzed using independent t-test. As a result, there was an interaction between groups in the average number of kicks among the performance ability through the TAAA (Taekwondo-specific aerobic anaerobic agility) test , and the main effect between groups was shown (p<.05). In addition, there was an interaction between groups and time in the kick fatigue index (p<.05). In lactate, the time-interaction were shown (p<.05) and interaction effects and inter-time main effects were observed in lactate dehydrogenase (LDH)(p<.05). In the case of ammonia, the interaction effect between the group and time was shown (p<.05). These results show that L-arginine intake can play a positive role in quickly synthesizing nitric oxide in blood vessels and expanding blood vessels to quickly remove fatigue-causing substances in the body for athletes who are easily exposed to fatigue after high-intensity training for male college Taekwondo Kyorugi players. Therefore, it is recommended to take L-arginine as a way to improve the performance of high-intensity elite Taekwondo Kyorugi players and recover from fatigue.

• Childhood Kidney Diseases
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• v.3 no.2
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• pp.123-129
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• 1999

Purpose: Acute poststreptococcal glomerulonephritis(APSGN) is a renal disease which is characterized by glomerular proliferation and inflammatory changes due to immune reaction. Although the 95% of patients with APSGN seems to recover fully and present as benign course, the remaining patients show poor prognosis. Therefore comparative retrograde study between APSGN with and without nephrotic syndrome was done to find out the any prognostic indicator to predict the outcome in patients with APSGN. Methods: We had retrospectively analyzed seventy-one patients who were diagnosed as APSGN clinically from Mar.1989 to Feb.1999 in Yonsei university medical center. Sixty-four of the patients was APSGN without nephrotic syndrome(Group A) and seven patients were in APSGN with nephrotic syndrome(Group B). Results: Patients who were diagnosed as APSGN with nephrotic syndrome were seven(9.9%) out of seventy-one. In the comparative study, sex ratio was 1:1 in group A and 1.9: 1 in group B, onset mean age was $8.9{\pm}2.6$ in group A and $8.8{\pm}2.6$ in group B. Following clinical profiles were compared but there were no significant difference between these two groups: WBC count($9413{\pm}2964\;vs\;9368{\pm}2650(/mm^3)$), hemoglobin($10.6{\pm}1.2\;vs\;10.0{\pm}0.9(gm/dL)$), ASO($746.1{\pm}640.7\;vs\;614.9{\pm}475.9(IU/ml)$), $C_3(20.1{\pm}17.0\;vs\;16.9{\pm}13.1(mg/dL)$), $C_4(22.8{\pm}9.5\;vs\;22.6{\pm}6.9(mg/dL)$), BUN($25.8{\pm}26.1\;vs\;28.1{\pm}14.5(mg/dL)$), creatinin($0.8{\pm}0.3\;vs\;0.8{\pm}0.3(mg/dL)$), $C_{cr}(80.6{\pm}28.8{\pm}62.4{\pm}31.4(ml/min/1.73\;m^2$)), the duration of edma, gross hematuria, and hypertension. However, we found that there were a significant difference in the duration of proteinuria($1.95{\pm}2.27\;vs\;13.3{\pm}21.1(months)$)(P<0.05), decreased $C_3$ duration($1.9{\pm}2.9\;vs\;7.3{\pm}5.0(weeks)$)(P<0.05) and especially it was proloned according to the amount of early urine protein excretion. Conclusion: Our study showed markedly prolonged duration of proteinuria and decreased $C_3$ duration in patients with APSGN with nephrotic syndrome. We were not able to find the definite prognostic factor that will guide the outcome of patients with APSGN accompaning nephrotic syndrome, but above findings seemed to represent as a relative indication of the outcome of the disease. All patients recovered completely and we did not experience any cases that progressed into the renal failure.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.1 no.2
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• pp.129-147
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• 1994

The purpose of this study was to examine the effect of deep breathing exercise with Incentive Spirometer on the pulmonary ventilatory function of postoperative patients. This experiment was operated by quasi-experimental design which was compared pre-experimental measures with post-experimental ones. The subject of this study was 46 inpatients who were scheduled for elective upper abdominal surgery under the general anesthesia in P National University Hospital in Pusan and classified into the experimental group(23 patients) and control group(23 patients) by using Incentive Spirometer or unusing one. The data were collected from November, 1, 1993, to December, 31, 1993. The effects of the deep breathing exercise on the pulmonary ventilatory function were compared between experimental group who were recieved deep breathing exercise with Incentive Spirometer and control group who were recieved same method without Incentive Spirometer. The Forced Vital Capacity (FVC) and the First Second Forced Expiratory Volume ($FEV_1$) were represented as index of the pulmonary ventilatory function and those were measured by Vitalograph Compact. The collected data were analysed by SPSS/PC+ (percentage, average, standard deviation, chi-square test, t-test, and ANOVA). The results were as follow : (1) The $FVC_s$ of the experimental group were significantly increased in course of time, 24, 48, 72 hours after surgery(F=3.530, P=0.035). (2) The $FVC_s$ and $FEV_{1S}$ of the control group were significantly increased in course of time, 24, 48, 72 hours after surgery ($FVC_s$ : F=3.480, P=0.037, $FEV_{1S}$ : F=6. 153, P=0.004). (3) The FVC which was measured at 72 hours after surgery was significantly higher in the experimental group than in the control group(t=2.620, P=0.013). (4) The $FEV_{1s}$ which were measured at 24 and 72 hours after surgery were significantly higher in the experimental group than in the control group(24hr. : t=2.530, P=0.017, 72hr. : t=2.540, P=0.016). (5) Among general characteristics, sex was significant variable which influenced to effect of pulmonary ventilatory function. In conclusion, this study showed that the deep breathing exercise with Incentive Spirometer was more effective to recover the pulmonary ventilatory function after surgery than the deep breathing exercise without Incentive Spirometer.

• Journal of Korean Academy of Nursing
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• v.2 no.1
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• pp.3-33
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• 1971

Nursing of today has as one of its objectives the solving of problems related to human needs arising from the demands of a rapidly changing society. This nursing objective, I believe, can he attained by the appropriate application of scientific principles in the giving of comprehensive nursing care. Comprehensive nursing care may be defined as nursing care which meets all of the patient's needs. the needs of patients are said to fall into five broad categories: physical needs, psychological needs, environmental needs, socio-economic needs, and teaching needs. Most people who become ill have adjustment problems related to their new situation. Because patient teaching is one of the most important functions of professional nursing, the success of this teaching may be used as a gauge for evaluating comprehensive nursing care. This represents a challenge foe the future. A questionnaire consisting of 67 items was distributed to 200 professional nurses working ill direct patient care at Yonsei University Medical Center in Seoul, Korea. 160 (80,0%) nurses of the total sample returned completed questionnaires 81 (50.6%) nurses were graduates of 3 fear diploma courser 79 (49.4%) nurses were graduates of 4 year collegiate nursing schools in Korea 141 (88,1%) nurses had under 5 years of clinical experience in a medical center, while 19 (11.9%) nurses had more than 5years of clinical experience. Three hypotheses were tested: 1. “Nurses had high levels of concept and knowledge toward patient teaching”-This was demonstrated by the use of a statistical method, the mean average. 2. “Nurses graduating from collegiate programs and diploma school programs of nursing show differences in concepts and knowledge toward patient teaching”-This was demonstrated by a statistical method, the mean average, although the results showed little difference between the two groups. 3. “Nurses having different amounts of clinical experience showed differences in concepts and knowledge toward patient teaching”-This was demonstrated by the use of a statistical method, the mean average. 2. “Nurses graduating from collegiate programs and diploma school programs of nursing show differences in concepts and knowledge toward patient teaching”-This was demonstrated by a statistical method, the mean average, although the results showed little difference between the two groups. 3. “Nurses having different amounts of clinical experience showed differences in concepts and knowledge toward patient teaching”-This was demonstrated by the use of the T-test. Conclusions of this study are as follow: Before attempting the explanation, of the results, the questionnaire will he explained. The questionnaire contained 67 questions divided into 9 sections. These sections were: concept, content, time, prior preparation, method, purpose, condition, evaluation, and recommendations for patient teaching. 1. The nurse's concept of patient teaching: Most of the nurses had high levels of concepts and knowledge toward patient teaching. Though nursing service was task-centered at the turn of the century, the emphasis today is put on patient-centered nursing. But we find some of the nurses (39.4%) still are task-centered. After, patient teaching, only a few of the nurses (14.4%) checked this as “normal teaching.”It seems therefore that patient teaching is often done unconsciously. Accordingly it would he desirable to have correct concepts and knowledge of teaching taught in schools of nursing. 2. Contents of patient teaching: Most nurses (97.5%) had good information about content of patient teaching. They teach their patients during admission about their diseases, tests, treatments, and before discharge give nurses instruction about simple nursing care, personal hygiene, special diets, rest and sleep, elimination etc. 3. Time of patient teaching: Teaching can be accomplished even if there is no time set aside specifically for it. -a large part of the nurse's teaching can be done while she is giving nursing care. If she believes she has to wait for time free from other activities, she may miss many teaching opportunities. But generally proper time for patient teaching is in the midmorning or midafternoon since one and a half or two hours required. Nurses meet their patients in all stages of health: often tile patient is in a condition in which learning is impossible-pain, mental confusion, debilitation, loss of sensory perception, fear and anxiety-any of these conditions may preclude the possibility of successful teaching. 4. Prior preparation for patient teaching: The teaching aids, nurses use are charts (53.1%), periodicals (23.8%), and books (7.0%) Some of the respondents (28.1%) reported that they had had good preparation for the teaching which they were doing, others (27.5%) reported adequate preparation, and others (43.8%) reported that their preparation for teaching was inadequate. If nurses have advance preparation for normal teaching and are aware of their objectives in teaching patients, they can do effective teaching. 5. Method of patient teaching: The methods of individual patient teaching, the nurses in this study used, were conversation (55.6%) and individual discussion (19.2%) . And the methods of group patient teaching they used were demonstration (42.3%) and lecture (26.2%) They should also he prepared to use pamphlet and simple audio-visual aids for their teaching. 6. Purposes of patient teaching: The purposes of patient teaching is to help the patient recover completely, but the majority of the respondents (40.6%) don't know this. So it is necessary for them to understand correctly the purpose of patient teaching and nursing care. 7. Condition of patient teaching: The majority of respondents (75.0%) reported there were some troubles in teaching uncooperative patients. It would seem that the nurse's leaching would be improved if, in her preparation, she was given a better understanding of the patient and communication skills. The majority of respondents in the total group, felt teaching is their responsibility and they should teach their patient's family as well as the patient. The place for teaching is most often at the patient's bedside (95.6%) but the conference room (3.1%) is also used. It is important that privacy be provided in learning situations with involve personal matters. 8. Evaluation of patient teaching: The majority of respondents (76.3%,) felt leaching is a highly systematic and organized function requiring special preparation in a college or university, they have the idea that teaching is a continuous and ever-present activity of all people throughout their lives. The suggestion mentioned the most frequently for improving preparation was a course in patient teaching included in the basic nursing program. 9. Recommendations: 1) It is recommended, that in clinical nursing, patient teaching be emphasized. 2) It is recommended, that insertive education the concepts and purposes of patient teaching he renewed for all nurses. In addition to this new knowledge, methods and materials which can be applied to patient teaching should be given also. 3) It is recommended, in group patient teaching, we try to embark on team teaching.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.119-130
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• 2004

Decrease in cardiac function after open heart surgery is due to an ischemia induced myocardial damage during surgery, and ischemic preconditioning, a condition in which the myocardial damage does not accumulate after repeated episodes of ischemia but protects itself from damage after prolonged ischemia due to myocytes tolerating the ischemia, is known to diminish myocardial damage, which also helps the recovery of myocardium after reperfusion, and decreases incidences of arrythmia. Our study is performed to display the ischemic preconditioning and show the myocardial protective effect by applying cardioplegic solution to the heart removed from rat. Material and Method: Sprague-Dawley male rats were used, They were fixed on a modified isolated working heart model after cannulation. The reperfusion process was according to non-working and working heart methods and the working method was executed for 20 minutes in which the heart rate, aortic pressure, aortic flow and coronary flow were measured and recorded. The control group is the group which the extracted heart was fixed on the isolated working heart model, recovered by reperfusion 60 minutes after infusion and preserved in the cardioplegic solution 20 minutes after the working heart perfusion and aortic cross clamp, The thesis groups were divided into group I, which ischemic hearts that were hypoxia induced were perfused by cardioplegic solution and preserved for 60 minutes; group II, the cardioplegic solution was infused 45 seconds (II-1), 1 minutes (II-2), 3 minutes (II-3), after the ischemia induction, 20 minutes after working heart perfusion and aortic cross clamp; and group III, hearts were executed on working heart perfusion for 20 minutes and aortic cross clamp was performed for 45 seconds (III-1), 1minute (III-2), 3 minutes (III-3), reperfused for 2 minutes to recover the heart, and then aortic cross clamping was repeated for reperfusion, all the groups were compared based on hemodynamic performance after reperfusion of the heart after preservation for 60 minutes. Result: The recovery time until spontaneous heart beat was longer in groups I, II-3, III-2 and III-3 to control group (p<0.01). Group III-1 (p<0.05) had better results in terms of recovery in number of heart rates compared to control group, and recovered better compared to II-1 (p<0.05). The recovery of aortic blood pressure favored group III-1 (p<0.05) and had better outcomes compared with II-1 (p<0.01). Group III-1 also showed best results in terms of cardiac output (p<0.05) and group III-2 was better compared to II-2 (p<0.05). Group I (p<0.01) and II-3 (p<0.05) showed more cardiac edema than control group. Conclusion: When the effects of other organs are dismissed, protecting the heart by infusion of cardioplegic solution after enforcing ischemia for a short period of time before the onset of abnormal heart beats for preconditioning has a better recovery effect in the cardioplegic group with preconditioning compared to the cardioplegic solution itself. we believe that further study is needed to find a more effective method of preconditioning.