• 한국주조공학회지
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• 제34권5호
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• pp.162-169
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• 2014

The effect of the mold preheat temperature on the solidification crack strength was investigated in AC2B aluminum alloy. A tension type apparatus as part of a solidification crack test which could measure the stress-strain relationship quantitatively was utilized. The evaluation of the solidification crack strength with varying mold preheat temperatures was performed by the test procedure established in this research. When the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the solidification crack strengths were found to be $7.8Kgf/cm^2$, $12.9Kgf/cm^2$ and $28.6Kgf/cm^2$, respectively. In the same way, when the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the corresponding temperatures of the failure sites were $610^{\circ}C$, $600^{\circ}C$ and $571^{\circ}C$, and the calculated solid fractions were 14.0%, 29.3% and 50.8% when the specimens failed, respectively. The solidification crack strength increased in proportion to the solid fraction of the failure site. The solidification crack strength obtained in this test is assumed to reflect the effects of metallurgical factors on the thermo-plastic characteristics of a solidifying alloy such as the grain size of the solid, the grain morphology, and the distribution of solid grain.

• 한국IT서비스학회지
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• 제19권3호
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• pp.57-73
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• 2020

The proportion of digital evidence in criminal cases has increased, while at the same time, the spread of the Internet has made it easy to delete information that is stored in another place and thus, the Internet is being used to delete online criminal evidence. To respond quickly and effectively to cybercrime, 29 countries signed the Convention on Cybercrime in 2001 through the Council of Europe. Article 16 of the Convention relates to the expedited preservation of stored computer data and requires signatories to adopt legislative measures to enable its competent authorities to order expeditious preservation of specified computer data where there are grounds to believe that the data is particularly vulnerable to loss or modification. More than 60 countries have joined the Convention since 2001 and have made efforts to improve their legal system in line with it. The United States legislated 18 U.S.C. § 2703(f) to preserve electronic evidence pending the issuance of a court order. The German Code of Criminal Procedure §§ 94~95 allows prosecution authorities to seize evidence or issue production orders without court control in urgent circumstances. A custodian shall be obliged to surrender evidence upon a request that evidence be preserved, and non-compliance results in punishment. Japan legislated the Criminal Procedure Act § 197(3) and (4) to establish a legal base for requesting that electronic records that are stored by an ISP not be deleted. The Korean Criminal Procedure Act § 184 outlines procedures for the preservation of evidence but does not adequately address the expeditious preservation of digital evidence that may be vulnerable to deletion. This paper analyzes nine considerations, including request subjects, requirements, and cost reimbursement to establish directions to improve the legal system for the expedited preservation of digital evidence. A new method to preserve online digital evidence in urgent cases is necessary.

• Journal of Chest Surgery
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• 제56권2호
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• pp.108-116
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• 2023

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) has recently gained popularity as an adjunct to resuscitation of patients with traumatic shock. However, the effectiveness of REBOA is still debated because of inconsistent indications across centers and the lack of medical records. The purpose of this study was to investigate the effectiveness and feasibility of REBOA by analyzing clinical results from a single center. Methods: This study included 96 patients who underwent REBOA between August 2016 and September 2021 at a regional trauma center according to the center's treatment algorithm for traumatic shock. Medical records, including the time of the decision to conduct the REBOA procedure, time of operation, type of aortic occlusion, and clinical outcomes, were collected prospectively and analyzed retrospectively. Patients were classified by REBOA protocol (group 1, 2, or 3) and survival status (survivor or non-survivor) for analysis. Results: The overall success rate of the procedure was 97.9%, and the survival rate was 32.6%. In survivors, blood pressure was higher than in non-survivors both before the REBOA procedure (p=0.002) and after aortic occlusion (p=0.03). The total aortic occlusion time was significantly shorter (p=0.001) and the proportion of partial aortic occlusion was significantly higher (p=0.014) among the survivors. The non-survivors had more acidosis (p<0.001) and higher lactate concentrations (p<0.001) than the survivors. Conclusion: REBOA may be a feasible bridge therapy for resuscitation of patients with traumatic shock. Prompt and accurate decision-making to perform REBOA followed by damage control surgery could improve survival rates and clinical outcomes.

• 대한정형외과학회지
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• 제55권3호
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• pp.229-236
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• 2020

목적: 초음파 유도하 요추 4번 신경근 차단술을 시행함에 있어 시술 전 자기공명영상(magnetic resonance imaging, MRI) 계측의 유용성을 알아보고자 하였다. 대상 및 방법: 이 연구는 후향적 연구로 2016년 3월부터 2017년 12월까지 본원 외래에 방문한 환자 중 요추 4번 신경근의 병변이 확인되며 선정 기준에 합당한 71명의 환자를 대상으로 하였다. 2016년 3월부터 2017년 2월까지 MRI 계측 없이 신경근 차단술을 시행한 31명의 환자를 A군, 2017년 3월부터 2017년 12월까지 시술 전 MRI 계측을 통해 신경근 차단술을 시행한 40명의 환자를 B군으로 분류하였다. A군은 MRI 계측 없이 pararadicular 접근법을 통하여 주사를 시행하였고 B군은 시술 전 MRI로 측정한 계측치를 바탕으로 하여 초음파 유도하 주사를 시행하였다. 시술 전, 시술 3시간 후, 2주 후, 6주 후, 12주 후에 수치평가척도(numeric rating scale, NRS) 점수를 이용하여 통증 호전 정도를 판정하였다. 결과: 시술 3시간 후 양호 이상의 결과를 보인 경우는 A군에서 51.6%, B군에서 67.5%였으며 시술 2주 후 양호 이상의 결과를 보인 경우는 A군에서 48.4%, B군에서 70.0%였다. 시술 6주 후 양호 이상의 결과를 보인 경우는 A군에서 58.1%, B군에서 62.5%, 시술 12주 후 양호 이상의 결과를 보인 경우는 A군에서 67.7%, B군에서 62.5%였다. 시술 3시간 후, 2주차에 유의하게 B군이 A군보다 증상 호전에 좋은 결과를 보였다(p<0.05). 만족스런 통증 완화를 위해 2주차에서 6주차 사이에 A군의 경우 2.8회, B군의 경우 1.7회의 반복적인 시술이 시행되었다(p<0.05). 결론: 시술 전 MRI를 통한 계측을 먼저 시행하고 이를 참고하여 초음파 유도하 요추 4번 선택적 신경근 차단술을 시행하는 것은 환자의 시술의 성공률을 높여 시술 후 2주 이내의 초기 통증을 완화하는데 도움이 될 것으로 생각된다.

• 대한치과보철학회지
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• 제53권3호
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• pp.262-275
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• 2015

상악 전치부와 같은 심미성이 요구되는 부위의 치료 시에는 건강하고, 주위조직과 조화를 이루며 매력적인 미소선의 형성을 염두에 두어야 한다. 이에 관하여 미소선, 연조직 및 경조직의 형태뿐 아니라 치아의 해부학적 형태와 비율 또한 고려하여야 한다. 상악 측절치의 왜소치(peg lateralis)로 인한 치간이개 및 부적절한 치은 형태로 인해 비심미적인 상악 전치부 비율을 가진 환자에서는 교정치료만으로 심미적 수복이 이루어지기 힘들 수 있다. 이런 경우, 교정치료가 끝난 이후 치아-치은-안면 구도에서의 진단 및 분석을 통한 치은절제술 및 보철적 수복을 통해 치아간의 근/원심, 폭/길이 비율을 개선시켜야 심미적으로 만족할 만한 결과를 얻어낼 수 있다. 또한, 상악 측절치의 왜소치(peg lateralis) 치아 비율 개선을 위한 보철물 제작 시 치질삭제가 적으며 인접치와 유사한 색조가 재현 가능하고 투명도가 높은 도재 라미네이트 비니어(Porcelain laminate veneer, PLV)가 선호되고 있다. 본 증례에서는 두 명의 20세 여자 환자로 교정치료 후 상악 측절치의 왜소치로 인한 치간이개 및 부적절한 치은 형태로 인해 비심미적인 상악 전치부 비율을 가진 환자에서의 체계적인 진단 및 치료과정을 통해 심미성이 개선된 보철 수복 증례를 보고하고자 한다.

• International Journal of Concrete Structures and Materials
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• 제8권2호
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• pp.173-182
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• 2014

An experimental investigation was carried out to evaluate the mechanical properties of concrete mixtures in which coarse aggregate was partially (30, 50 or 70 %) replaced with pre-washed municipal solid waste incineration (MSWI) bottom ash. Results indicated that bottom ash reduced the compressive strength, elastic modulus, and levels of heavy metals in leachate when used as a replacement for gravel, and that the maximum amount of MSWI bottom ash in concrete should not exceed 50 %. To analyze the effect mechanism of bottom ash in concrete, the degree of hydration and the following pozzolanic reaction characterized by the pozzolanic activity index, and the porosity distribution in cement mortar. The study indicates that improved properties of concrete are not solely later strength gain and reduced levels of heavy metals in leachate but also the progression of pozzolanic reactions, where a dense structure contains a higher proportion of fine pores that are related to durability.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.284-287
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• 2004

A high ductile fiber reinforced mortar has been developed by employing micromechanics-based design procedure. Micromechanical analysis was initially performed to properly select water-cement ratio, and then optimal mixture proportion was determined based on workability considerations, including desirable fiber dispersion without segregation. Subsequent direct tensile tests revealed that the fiber reinforced mortar exhibited high ductile uniaxial tension property, represented by $1.8\%$ strain capacity, which is around 100 times the strain capacity of normal concrete.

• 대한산업공학회지
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• 제27권1호
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• pp.89-94
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• 2001

There are many queueing systems where customers wait for service up to a certain amount of time and leave the system if they are not served during that time. This paper considers a finite capacity multi-server queueing system with Poisson input and Erlang service time, where a customer becomes a lost customer when his service has not begun within an exponential patient time after his arrival. Performance measures such as average queue length, the average number of customers in service, and the proportion of lost customers can be obtained exactly through the proposed numerical solution procedure.

• 대한산업공학회지
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• 제27권4호
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• pp.366-373
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• 2001

Economic component screening procedures for multi-component assembly products supplied with warranty are proposed. It is assumed that the screening variable is continuous and the performance variable is dichotomous. Logistic and normal models are considered; the proportion of conforming items is a logistic function of the screening variable in the logistic model and the screening variable given the performance variable is normally distributed in the normal model. Cost models are constructed which involve three cost components; screening inspection cost for each component, cost due to disposing a rejected component, and warranty cost for an assembly product. Methods of finding the optimal screening procedures are presented and numerical examples are given.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.235-237
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• 2005

This paper presents a method of incorporating weather effects in KEPCO systems reliability evaluation. The effects of adverse weather on composite power system FOR(Forced Outage Rate) increase considerably as the proportion of outages in adverse weather increases. It is therefore important to establish suitable and practical procedures for collecting adverse weather data which can be utilized in realistic KEPCO systems reliability assessment. The modeling procedure proposed in this paper also provides a realistic FOR in KEPCO systems using real historical data.