• 융합경영연구
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• 제11권5호
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• pp.45-55
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• 2023

Purpose: As one of the continuous studies on the offline distribution industry, the purpose of this study is to find ways for offline stores to respond to the growth of online shopping by identifying research trends on department stores. Research design, data and methodology: To this end, this study conducted word frequency analysis, word co-occurrence frequency analysis, BERTopic, LDA, and dynamic topic modeling using Python 3.7 on a total of 551 English abstracts searched with the keyword 'department store' in scienceON as of October 10, 2022. Results: The results of word frequency analysis and co-occurrence frequency analysis revealed that research related to department stores frequently focuses on factors such as customers, consumers, products, satisfaction, services, and quality. BERTopic and LDA analyses identified five topics, including 'store image,' with 'shopping information' showing relatively high interest, while 'sales systems' were observed to have relatively lower interest. Conclusions: Based on the results of this study, it was concluded that research related to department stores has so far been conducted in a limited scope, and it is insufficient to provide clues for department stores to secure competitiveness against online platforms. Therefore, it is suggested that additional research be conducted on topics such as the true role of department stores in the retail industry, consumer reinterpretation, customer value and lifetime value, department stores as future retail spaces, ethical management, and transparent ESG management.

• Tuberculosis and Respiratory Diseases
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• 제55권3호
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• pp.267-279
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• 2003

연구배경 : 흡연과 폐암 발생 사이의 인과관계는 잘 알려진 사실이지만, 흡연 습관 즉 흡연량 및 기간, 흡연을 처음 시작한 나이, 담배 연기의 흡입 정도, 그리고 담배의 종류 등 다양한 요소들이 폐암 발생에 더욱 크게 작용한다고 한다. 그러나 우리나라에서는 이에 대한 연구 특히 일상동안의 흡연으로 흡입된 타르, 니코틴이 폐암 발생에 미치는 영향에 대한 연구는 없는 실정이다. 방 법 : 연세대학교 의과대학 세브란스병원에 내원한 45세에서 75세 사이의 폐암 환자 150명과 나이와 성별을 일치시킨 폐암이 아닌 질병을 가진 환자 300명을 대상으로 흡연 습관에 따른 폐암 발생 및 폐암 조직형의 교차비, 일생동안 흡입한 티르와 니코틴 총량을 설문지를 통해 조사하여 산술적으로 합산하여 흡입 총량에 따른 교차비를 알아보고자 환자-대조군 연구를 시행하였다. 각 담배에 포함된 개피 당 타르, 니코틴 함량을 문헌을 통해 조사하였고, 개개인의 흡연 습관의 차이에 따른 일생동안 흡입된 타르와 니코틴의 함량을 구하였다. 결 과 : 폐암 환자군 150명 중 현재 흡연자가 가장 많았고, 여자들 중에서는 비흡연자가 가장 많았으며, 대조군도 유사하였다. 폐암 환자군의 흡연 습관 중 통계적으로 의미가 있었던 것은 흡연 기관과 총 갑년, 최근 2년간 피운 하루 당 개피 수이었고, 흡연 시작 나이와 필터 없는 담배를 피운 기간은 대조군과 차이가 없었다. 폐암 조직형 중 편평상피세포암과 소세포암은 남자와 현재 흡연자가 가장 많았으며, 선암은 여자와 비흡연자가 가장 많았다. 흡연 습관들 중 Kreyberg I에서는 흡연 시작 나이가 어릴수록, 흡연 기간이 길수록, 총 갑년이 높을수록, 최근 2년간 피운 하루 당 개피수가 많을수록, 필터없는 담배를 피운 기간이 길수록 교차비는 증가하였다. 또한 산술적으로 합산한 일생동안 흡입된 타르와 니코틴의 총량이 높을수록 교차비가 높았다. 그러나 Kreyberg II에서는 각 흡연 습관들의 교차비는 통계적으로 의미가 없었다. 결 론 : 본 연구는 단일 병원에서 조사되었고, 환자의 기억에 의존하는 제한점이 있으나, 흡연 습관이 폐암 발생, 폐암 조직형 등과 상당한 연관이 있는 것으로 조사되었고, 일생동안 흡연 습관의 변화를 타르와 니코틴의 흡입된 총량으로 산술적으로 계산하였다는 의의가 있다. 향후 이에 대한 대규모 연구가 필요할 것으로 생각된다.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6419-6424
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• 2014

스마트폰 배터리 사용시간이 짧아지는 문제의 해결방안으로 PMP(Protection Module Package)를 제안한다. PMP란 보호회로가 하나의 반도체로 구성하는 것을 의미한다. 이번 연구에서는 유한요소 해석을 통하여 EMC 모듈의 적합한 Epoxy 재질을 선정하기 위한 기반연구를 수행하였다. 먼저 굽힘강도 해석을 통하여 외부 힘에 대한 응력을 비교하였다. 다음 열해석에서, 계산한 발열량을 사용하여 EMC 모듈의 내부 부품의 온도 변화를 비교한다. 마지막으로, 충전률은 EMC 모듈 내의 용융된 에폭시를 주입하여 비교하였다.

• 한국대기환경학회지
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• 제18권6호
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• pp.465-474
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• 2002

In order to reflect variability due to exposure factors as well as to assess uncertainty associated with cancer risk posed by airborne trace metals, a Monte Calro analysis has been made in this study. Input parameters for Monte Carlo analysis were developed or adjusted using body weight, lifetime, and exposure frequency of Koreans. Ambient distributions of toxic metals were founded to be lognormal distributions for most of them using goodness-of-fit tests. Thus, the 95% UCL and 95% LCL of carcinogenic metals were estimated by H-statistic method for lognormal distribution, respectively. The results of Monte Carlo analysis of 95% UCL showed that the 95th percentile risks for men and women were 1.2 and 1.1 times higher than an acceptable risk of 10$^{-5}$ , respectively. The probabilities which those risks exceed the acceptable risk were estimated to be 8% and 6%, respectively, while to be 95% and 94%, respectively on the basis of the minimum acceptable risk of 10$^{-6}$ , respectively. Approximately 90% of total cancer risk came from human carcinogens such as arsenic and hexavalent chromium. Therefore, it is necessary to properly manage both arsenic and hexavalent chromium emissions in the study area.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.182-189
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• 2018

A neutron generation system was developed to induce fissile fission in a lead slowing down spectrometer (LSDS) system. The source neutron is one of the key factors for LSDS system work. The LSDS was developed to quantify the isotopic contents of fissile materials in spent nuclear fuel and recycled fuel. The source neutron is produced at a multilayered target by the (e,${\gamma}$)(${\gamma}$,n) reaction and slowed down at the lead medium. Activation analysis of the target materials is necessary to estimate the lifetime, durability, and safety of the target system. The CINDER90 code was used for the activation analysis, and it can involve three-dimensional geometry, position dependent neutron flux, and multigroup cross-section libraries. Several sensitivity calculations for a metal target with different geometries, materials, and coolants were done to achieve a high neutron generation rate and a low activation characteristic. Based on the results of the activation analysis, tantalum was chosen as a target material due to its better activation characteristics, and helium gas was suggested as a coolant. In addition, activation in a lead medium was performed. After a distance of 55 cm from the lead surface to the neutron incidence, the neutron intensity dramatically decreased; this result indicates very low activation.

• 대한조선학회논문집
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• 제56권3호
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• pp.251-262
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• 2019

This paper is about design concept and simplified analysis method against dropped object events. The ships and offshore structures are exposed to various types of dropped object accidents such as laydown area struck by drill collar and topside deck hit by food container during their lifetime. Mitigation can be accomplished by proper facility layout and designing structures to safely absorb energy from accidental loads. It shall be designed to avoid loss of life, environmental pollution and loss of assets. Impact loads can lead to structural global collapse of the main structure or punching of a local barrier type structure with potential to escalate directly or indirectly to a global collapse of the structure. This study provides the background information on the issue of dropped object of the shipyard and also focuses on structural assessment of the local individual component such as deck plate, stiffener and web/girder by using simplified analysis method. The results of the simplified analysis method were compared with numerical results using non-linear finite element simulation.

• 융합경영연구
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• 제10권6호
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• pp.27-37
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• 2022

Purpose: The purpose of this study is to derive various ways to realize customer satisfaction for the development of the service industry by exploring research trends related to customer satisfaction, which is presented as an important goal in the service industry. Research design, data and methodology: To this end, 1,456 papers with English abstracts using scienceON were used for analysis. Using Python 3.7, word frequency and co-occurrence analysis were confirmed, and topics related to research trends were classified through BERTopic and LDA. Results: As a result of word frequency and co-occurrence frequency analysis, words such as quality, intention, and loyalty appeared frequently. As a result of BERTopic and LDA, 11 topics such as 'catering service' and 'brand justice' were derived. As a result of trend analysis, it was confirmed that 'brand justice' and 'internet shopping' are emerging as relatively important research topics, but CRM is less interested. Conclusions: The results of this study showed that the 7P marketing strategy is working to some extent. Therefore, it is proposed to conduct research related to acquisition of good customers through service price, customer lifetime value application, and customer segmentation that are expected to be needed for the development of the service industry.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.406-406
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• 2016

To get high efficiency n-type crystalline silicon solar cells, passivation is one of the key factor. Tunnel oxide (SiO2) reduce surface recombination as a passivation layer and it does not constrict the majority carrier flow. In this work, the passivation quality enhanced by different chemical solution such as HNO3, H2SO4:H2O2 and DI-water to make thin tunnel oxide layer on n-type crystalline silicon wafer and changes of characteristics by subsequent annealing process and firing process after phosphorus doped amorphous silicon (a-Si:H) deposition. The tunneling of carrier through oxide layer is checked through I-V measurement when the voltage is from -1 V to 1 V and interface state density also be calculated about $1{\times}1012cm-2eV-1$ using MIS (Metal-Insulator-Semiconductor) structure . Tunnel oxide produced by 68 wt% HNO3 for 5 min on $100^{\circ}C$, H2SO4:H2O2 for 5 min on $100^{\circ}C$ and DI-water for 60 min on $95^{\circ}C$. The oxide layer is measured thickness about 1.4~2.2 nm by spectral ellipsometry (SE) and properties as passivation layer by QSSPC (Quasi-Steady-state Photo Conductance). Tunnel oxide layer is capped with phosphorus doped amorphous silicon on both sides and additional annealing process improve lifetime from $3.25{\mu}s$ to $397{\mu}s$ and implied Voc from 544 mV to 690 mV after P-doped a-Si deposition, respectively. It will be expected that amorphous silicon is changed to poly silicon phase. Furthermore, lifetime and implied Voc were recovered by forming gas annealing (FGA) after firing process from $192{\mu}s$ to $786{\mu}s$. It is shown that the tunnel oxide layer is thermally stable.

• 대한전자공학회논문지TC
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• 제44권9호
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• pp.25-37
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• 2007

애드혹 네트워크에서 수명을 연장하기 위한 방법 중 하나인 경로 재설정 기법은 일정 노드로 라우팅 기능 부담의 편중을 막기 위해 일정량의 에너지 사용 후, 새로운 경로를 다시 찾는다. 경로 재설정 기법은 라우팅 기능 분담에 의한 네트워크 수명 연장 측면에서 뛰어난 성능을 보인다. 그러나 경로 재설정은 플러딩을 바탕으로 하는 경로 탐색 과정이 포함되기 때문에 그 시그널링 오버헤드는 상당하며, 경로 재설정 기법의 에너지 효율성을 감소시킬 위험이 있다. 즉, 잦은 경로 재설정이 발생할 경우 시그널링 오버헤드로 인해 그 성능 향상이 반감될 수 있다. 본 논문에서 제안하는 경로 선택 알고리즘(Algorithm for Route Reacquisition with Overhead Weakener, ARROW)은 패킷 전송 비용과 함께 시그널링 오버헤드의 정도를 나타내는 경로 재설정 비용을 계산하여 경로 선택 과정에 활용한다. ARROW는 경로의 재설정 과정에서 발생하는 시그널링 오버헤드를 줄이는 새로운 알고리즘으로, 패킷 전송 비용만으로 경로 선택이 어려울 경우 경로 재설정 비용을 경로 선택 과정에서 고려하여 재설정 과정 발생 횟수를 줄임으로써 네트워크의 에너지를 효율적으로 사용할 수 있다. 재설정 비용이 고려된 ARROW와 고려되지 않은 알고리즘의 성능을 비교, 분석하기 위해 2차원 마코프 체인을 이용하여 애드혹 네트워크를 모델링 한다. 모델을 이용하여 분석한 결과 제안된 알고리즘은 시그널링 오버헤드와 네트워크 수명 측면에서 타 알고리즘 보다 뛰어남을 확인하였다.

• Journal of Preventive Medicine and Public Health
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• 제29권3호
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• pp.679-692
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• 1996

This study was performed to find the prevalence and the associated risk factors with low back pain(LBP) of the staffs in a university at Kwang-ju city. The data were collected by a questionnaire including SDS(self - rating depression Scale) battery from September 1st to October 15th, 1996. The results were as follows; 1. The prevalence rate of LBP during lifetime was 73.1%, 53.1% for the last one year, and 23.6% for the last one week. 2. Statistically significant factors related to LBP during lifetime were sex and satisfaction with job. Sex, smoking, alcohol drinking, occupation, work posture, forward bending of trunk and satisfaction with job were selected as significant factors related to LBP during the last one year. The significant determinants related with LBP during the last one week were sex, smoking, alcohol drinking, occupation, forward bending of trunk and satisfaction with job. 3. Through the analysis of self - rating depression scores according to LBP, respondents with LBP had the significantly higher value of physiological disturbances and lower value of psychomotor activities than those without LBP. 4. Through the multivariate logistic regression, significantly associated factors with LBP during lifetime were selected to be female(OR=2.63, 95% CI : $1.08\sim6.40$), dissatisfaction with job(OR=2.16, 95% CI : $1.16\sim4.15$), those for the last one year were chosen to be female(OR=2.30, 95% CI : $1.03\sim5.12$), forward bending of trunk(OR=2.18, 95% CI : $1.26\sim3.79$), dissatisfaction with job(OR=1.84, 95% CI : $1.06\sim3.21$), and those for the last one week were female(OR=3.00, 95% CI : $1.17\sim7.69$), forward bending of trunk(OR=2.85, 95% CI : $1.38\sim5.88$). In conclusion, for effective prevention of the LBP at work site, appropriate improvement of work posture and various psychological factors should be considered.