• 자원리싸이클링
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• 제29권3호
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• pp.11-23
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• 2020

본 연구에서는 정선 신예미 광산 철광석을 대상으로 볼밀에 의한 분쇄 및 단체분리 특성을 파악하고자 하였다. 자력 선별을 통해 얻은 세 가지 품위의 시료에 대해, 볼밀 단일 입도 분쇄실험 및 비선형 계획법을 이용한 역산법으로 물질수지방정식을 구성하는 분쇄 함수 인자를 도출하였다. 그 결과 철광석 품위의 증가에 따라 분쇄율은 감소하였으며, 입도 민감도는 감소하였다. 이는 철광석 내의 자철석 입자가 미소 균열의 전파를 지연하는 효과에 기인하는 것으로 판단된다. 분쇄 분포 관찰 결과, 품위가 증가할수록 압축 및 충격 파괴가 주된 파분쇄 메커니즘으로 나타났으며, 이는 입자 내부 자철석 입자의 응력 분산 효과에 기인하는 것으로 판단된다. 분석 결과 단체분리도는 품위 증가 및 입도 감소에 따라 증가하였다. 분쇄함수와 입도-단체분리도 관계를 이용, 분쇄진행에 따른 단체분리도 변화를 예측할 수 있는 모델을 수립하였으며, 본 연구를 통해 도출한 분쇄함수들에 실제 운전 조건에 따른 스케일업 인자 적용 시, 실제 광산 공정에서의 분쇄시간에 따른 입도 및 단체분리도를 예측할 수 있을 것으로 판단된다.

• 한국진공학회지
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• 제22권4호
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• pp.188-192
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• 2013

반도체 소자의 소형화, 고집적화로 박막의 다층화 및 선폭 감소로 인한 실리콘 웨이퍼와 금속 박막 사이의 확산을 방지하기 위한 많은 연구가 이루어지고 있다. 본 연구는 tungsten (W)을 주 물질로 증착시 nitrogen (N)의 유량을 2.5~10 sccm으로 변화시키며 증착된 확산방지막의 nano-mechanics 특성에 대해 연구하였다. 증착률, 비저항 및 결정학적 특성을 ${\beta}$-ray backscattering spectroscopy, 4-point probe, X-ray diffraction (XRD)을 이용하여 측정한 후 Nano-indenter를 사용하여 nano-mechanics 특성을 조사하였다. 그 결과 질소 가스 유량이 5 sccm 포함된 박막에서 표면 경도(surface hardness)는 10.07 에서 15.55 GPa로 급격하게 증가하였다. 이후 질소가스의 유량이 7.5 및 10 sccm에서는 표면 경도가 각각 12.65와 12.77 GPa로 질소 가스 유량이 5 sccm인 박막보다 표면경도가 상대적으로 감소하였다. 이는 박막 내 결정질과 비정질의 W과 N의 결합 비율의 차이에 의한 영향으로 생각되며, 또한 압축응력에 기인한 스트레스 증가가 원인으로 판단된다.

• Asian Spine Journal
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• 제12권6호
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• pp.1060-1068
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• 2018

Study Design: Retrospective study. Purpose: Lumbar intervertebral disc degeneration is an important cause of low back pain. Overview of Literature: Spinal fusion is often reported to have a good course for adolescent idiopathic scoliosis (AIS). However, many studies have reported that adjacent segment degeneration is accelerated after lumbar spinal fusion. Radiography is a simple method used to evaluate the orientation of the vertebral column. magnetic resonance imaging (MRI) is the method most often used to specifically evaluate intervertebral disc degeneration. The Pfirrmann classification is a well-known method used to evaluate degenerative lumbar disease. After spinal fusion, an increase in stress, excess mobility, increased intra-disc pressure, and posterior displacement of the axis of motion have been observed in the adjacent segments. Methods: we retrospectively secured and analyzed the data of 15 patients (four boys and 11 girls) with AIS who underwent a spinal fusion surgery. We studied the full-length view of the spine (anterior-posterior and lateral) from the X-ray and MRI obtained from all patients before surgery. Postoperatively, another full-length spine X-ray and lumbosacral MRI were obtained from all participants. Then, pelvic tilt, sacral slope, curve correction, and fused and free segments before and after surgery were calculated based on X-ray studies. MRI images were used to estimate the degree to which intervertebral discs were degenerated using Pfirrmann grading system. Pfirrmann grade before and after surgery were compared with Wilcoxon signed rank test. While analyzing the contribution of potential risk factors for the post-spinal fusion Pfirrmann grade of disc degeneration, we used generalized linear models with robust standard error estimates to account for intraclass correlation that may have been present between discs of the same patient. Results: The mean age of the participant was 14 years, and the mean curvature before and after surgery were 67.8 and 23.8, respectively (p<0.05). During the median follow-up of 5 years, the mean degree of the disc degeneration significantly increased in all patients after surgery (p<0.05) with a Pfirrmann grade of 1 and 2.8 in the L2-L3 before and after surgery, respectively. The corresponding figures at L3-L4, L4-L5, and L5-S1 levels were 1.28 and 2.43, 1.07 and 2.35, and 1 and 2.33, respectively. The lower was the number of free discs below the fusion level, the higher was the Pfirrmann grade of degeneration (p<0.001). Conversely, the higher was the number of the discs fused together, the higher was the Pfirrmann grade. Conclusions: we observed that the disc degeneration aggravated after spinal fusion for scoliosis. While the degree of degeneration as measured by Pfirrmann grade was directly correlated by the number of fused segments, it was negatively correlated with the number of discs that remained free below the lowermost level of the fusion.

• 해양환경안전학회지
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• 제28권2호
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• pp.377-384
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• 2022

선박, 잠수함이 추진하면 수중구조물 후류에 와류가 발생하고 이에 따른 와류기인 구조진동이 유발된다. 최근 선박, 잠수함의 고속화 및 대형화 추세에 따라 고차모드에서 유발되는 와류기인 진동 및 피로파괴에 대한 중요성이 강조되고 있다. 고속 유속환경의 와류는 저속 유속환경 대비 큰 진동을 유발하므로 이에 관한 연구가 필요하다. 본 연구에서는 수중날개 고차모드에서 유발되는 와류기인 진동을 예측하기 위한 하이브리드 유체구조연성 해석 방법론을 제시하였다. 고차모드를 고려한 하이브리드 유체구조연성 해석을 수행하여 와류기인 진동을 도출하고 실험결과와 비교함으로써 방법론을 검증하였다. 최종적으로 와류기인 진동으로부터 도출된 최대 von Mises 응력을 노르웨이 선급에서 제시한 S-N 선도에 적용함으로써 고차모드 유체구조연성 해석의 효용성을 확인하였다. 고차모드를 고려하여 와류기인 진동응답을 도출할 경우 유체구조연성에 의한 락인(Lock-in) 특성을 확인하였으며 고려하지 않은 경우 대비 진동응답과 최대 von Mises 응력에서 10배 이상의 차이를 보였다. 향후에는 외팔보 경계조건 및 형상에 대한 확장연구가 필요하다.

• Asia Marketing Journal
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• 제15권3호
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• pp.15-29
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• 2013

Shopping is considered a 'must-do' activity for most people on travel. One of the major parts of tourist shopping is the purchasing of souvenirs. Souvenirs are universally associated with tourism as a commercially produced and purchased object to remind the purchaser of the experience. Recently, Korea becomes one of the most popular destinations that many Asian tourists like to visit. Among those Asian tourists, the number of Thai tourists bound for Korea shows an incredible rapid growth. Thai people pick Korea and Seoul as their favorite country and city to visit for three consecutive years since 2009. One of the major reasons why Thais are choosing to tour Korea is the enthusiasm for Korean pop culture. That is, 'Hallyu' has influenced Thais' decision to visit Korea and purchase Korean products. The primary objective of the current research is to explore the shopping experiences of Thai tourists, specifically their souvenir shopping. It adopts a reflexive interpretive approach to bring light to the various meanings Thai tourists attach to the souvenirs they purchase in Korea. In order to accomplish the objective, the individual interviews were conducted. A total of 12 Thais who have experienced traveling in Korea participated in the study. Four themes were identified through interview text analysis. First, the research participants almost always purchase souvenirs in Korea because the souvenirs represent their identities as tourists. Especially, they purchase the souvenirs as gifts for others, including family members, friends, and colleagues. The souvenirs as gifts show love and thanks to others, and they cement the social relationship. However, purchasing souvenirs for others is more like the moral obligations which evoke the psychological stress. Secondly, the research participants feel closer to Korea while shopping souvenirs around. Thirdly, they obtain imaginative experiences and pleasure through souvenirs related to the Korean pop culture. Souvenirs provide them to visually extraordinary experiences. Lastly, souvenirs purchased in Korea act as visible status marker when they go back to Thailand. They show the socioeconomic status and lifestyles. Tourists themselves and others place special value to souvenirs that were purchased out of Thailand. The findings of this study are of both academic and practical importance. Souvenirs are among the most pervasive elements of the travel experience. However, souvenir shopping is the complicated consumer behavior within tourism both from business and social science perspectives. Along the same line, it needs strategic approaches in order to maximize the economy effects. It concludes by suggesting how further research could offer unique insights into how the souvenirs are positioned both in the context of tourism academics and industry.

• 대한치위생과학회지
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• 제1권2호
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• pp.41-52
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• 2018

The purpose of this study was to examine the state of oral prophylaxis practice among dental hygiene students and their awareness of musculoskeletal diseases in an effort to provide some information on how to strengthen education on treatment posture to manage musculoskeletal diseases and how to raise awareness of musculoskeletal diseases. From November 2 to 13, 2016, a self-administered survey was conducted on 653 sophomores, juniors and seniors with an experience of oral prophylaxis practice. SPSS version 20.0 for Windows was employed to analyze the collected data. The findings of the study were as follows: 1. The largest group that accounted for 37.4% responded that the total number of students undergoing oral prophylaxis practice during a semester was four to six. The biggest group that represented 65.4% answered that the required practice time per student was one to fewer than three hours. 76.0% continued to be in the repeated same posture. 2. As for the posture of patients, supine position was most common for the maxillary sinus, which accounted for 82.2%. And semi-upright position was most common for the mandibular sinus, which represented 49.6%. 3. In regard to the burden of oral prophylaxis practice, 33.9% considered the required for the practice appropriate. 42.3% took the repeated long-lasting posture, and 53.5% were under physical pressure. 55.4% suffered from mental pressure and stress. 4. The most dominant musculoskeletal area that they experienced pain after oral prophylaxis practice was neck with 52.5%; waist with 48.2, shoulders/wrists/hands with 45.5, back with 10.3, buttocks with 4.1, elbows with 2.3, legs with 2.1, ankles/feet with 0.8 and knees with 0.6%. 5. Concerning the maintenance of repeated treatment postures and pain experience, the students who continued to be in the repeated same position underwent more pain than the others who didn't on the shoulders(2.92±1.05), in the waist(3.02±1.01), buttocks(1.75±0.92), elbows(1.55±0.79) and ankles/foot(2.52±1.25). The differences were statistically significant(p<.05, p<.01). 6. As to educational experience on treatment posture and musculoskeletal diseases, 88.8% received education on treatment posture; 87.9%, on what position should be taken in times of cooperation; 46.9%, on musculoskeletal diseases; 51.9%, on carpal tunnel syndrome; 42.3%, on varicose vein. The students who replied education on occupational diseases was necessary accounted for 89.6%. 7. The students who experienced treatment posture education were better aware of the causes of musculoskeletal diseases(3.23±3.00), ways for preventing the diseases(3.33±.834) and how to stretch the body(3.63±.858). The differences were statistically significant(p<.05, p<.001). 8. The students who experienced education on occupational diseases heard more about musculoskeletal diseases(3.27±.965), were better cognizant of the causes of the diseases(3.45±.847), were better aware of how to prevent them(3.55±.805) and found themselves to know how to stretch to prevent the diseases (3.73±.826). The differences were statistically significant(p<.001).

• 한국작물학회지
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• 제27권3호
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• pp.183-192
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• 1982

1961-1980년의 20개년간 수도 재배면적은 거의 일정하였으나 생산량은 1961년의 3,462.6천t에서 1977년의 6,0056.천t까지 73.4%가 증가되었는데 이는 재배기술의 개선과 더불어 다수성 통일성 품종의 육성 보급에 힘입은 바 크다 할 것이다. 그러나 1978년 통일형 품종의 도열병 신균계에 대한 리병화와 더불어 계속된 이상기상으로 하여 1980년의 생산량은 1960년대 수준으로 떨어지므로서 수도작은 새로운 국면에 처하게 되었다. 한편 통일품종이 육성 보급된 1971년을 전후한 20개년 생산성은 계속 증가되어 왔으나 농가와 시험연구기관간에 수량차이는 1960-1971년의 79kg/10a에서 1972-1980년의 101kg/10a으로 점차로 커져왔고, 또한 동기간중 지역간 차이도 50-60kg/10a과 80kg/10a으로 더 커지고 있는 것으로 나타났다. 따라서 품종의 생산능력을 증대시키므로서 전체 생산성의 상한선은 제고하였지만 절대편차는 변화시키지 못하였음을 입증해주고 있다. 그간의 생산성 증가에 있어서 품종적 요인이 40%이고 기술적 요인을 13%로 추정할 경우 나머지 47%는 품종과 기술외적인 요인으로 볼 수 있을 것인데 이에 대하여는 최근 사회적, 생산기반조성 및 환경개선 등 여러 각도에서 집중적으로 논의되어왔다. 물론 재배환경의 균일화나 재배기술의 평준화는 기대하기 어려운 요인이라 하더라도 농가수량과 시험장수량과의 차이 20%, 지역간 차이 20%를 가능한 줄이는 방향으로 노력해 간다면 현재의 품종 생산능력과 기술수준으로서도 상당한 정도의 증수를 기대할 수 있을 것으로 보인다. 이와 같은 효과를 기대하기 위하여는 다음과 같은 요인들이 착실하게 지속적으로 실천되어져야 할 것이다. 첫째, 품종의 생산능력 증대와 재해 저항성 증진을 위한 육종사업과 재배기술개선을 위한 수도의 생리ㆍ생태적 기초연구의 강화. 둘째, 안정된 생산기반 조성 특히 지력증진과 관배수시설을 위한 지속적 노력. 셋째, 농민들의 생산의욕 고취를 위한 안정된 정책적 뒷받침. 넷째, 장기계획 수립을 위한 정확한 통계조사 등이라 하겠다.

• 콘크리트학회논문집
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• 제21권3호
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• pp.347-358
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• 2009

최근에 들어서 국내에서도 무량판 구조 (flat plate slab)가 적용될 수 있는 여건이 마련되어가고 있다. 그러나 무량판 구조는 보가 없는 구조이기 때문에 일반적인 라멘구조형식에 비하여 처짐 제어가 어려우며, 포스트텐션 (post-tension) 공법은 이러한 문제점을 극복하기 위한 매우 효율적인 방법이다. 포스트텐션 구조를 적용하면 슬래브 두께의 증가 없이도 효율적으로 슬래브의 처짐을 제어 할 수 있다. 그러나, 이러한 장점에도 불구하고, 국내에서 포스트-텐션의 적용은 비용증가, 기술적인 문제, 경험부족 등으로 인하여 그 적용이 매우 제한적이다. 따라서 전구간 포스트텐션 (full-PT)에 대한 부담을 줄이고 나아가 기존 포스트텐션 구조형식의 시공성을 향상하기 위하여 본 연구에서는 슬래브 내부에서 긴장작업을 수행할 수 있는 상향긴장식 부분PT공법을 제안하였다. 이러한 상향긴장방식은 정착구를 필요에 따라 다양한 위치에 설치할 수 있기 때문에 처짐 효율에 대한 분석이 필요하며, 정착구 후면에서 인장응력을 야기시키는 문제점이 있다. 따라서, 본 연구에서는 상향긴장식 부분PT공법 적용할 때 정착구 위치에 따른 처짐효율분석, 유한요소해석 및 스트럿-타이를 이용한 인장응력 또는 인장력 해석 등을 실시하였으며, 상향긴장식 부분PT공법을 실제로 현장에 적용하고, 계측결과를 해석결과와 비교 분석함으로써 현장적용성을 알아보았다. 상향긴장식 부분PT공법은 처짐 또는 인장응력이 크게 발생되는 부분 구간에만 선택적으로 적용하면 적은 비용증가로 큰 처짐효율을 얻어낼 수 있음을 확인하였다.

• 대한인간공학회지
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• 제35권4호
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• pp.293-305
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• 2016

Objective: This study aims to measure cognitive load levels by analyzing the EEG of Koreans and foreigners, when they read a Korean text with care selected by level from the grammar and vocabulary aspects, and compare the cognitive load levels through quantitative values. The study results can be utilized as basic data for more scientific approach, when Korean texts or books are developed, and an evaluation method is built, when the foreigners encounter them for learning or an assignment. Background: Based on 2014, the number of the foreign students studying in Korea was 84,801, and they increase annually. Most of them are from Asian region, and they come to Korea to enter a university or a graduate school in Korea. Because those foreign students aim to learn within Universities in Korea, they receive Korean education from their preparation for study in Korea. To enter a university in Korea, they must acquire grade 4 or higher level in the Test of Proficiency in Korean (TOPIK), or they need to complete a certain educational program at each university's affiliated language institution. In such a program, the learners of the Korean language receive Korean education based on texts, except speaking domain, and the comprehension of texts can determine their academic achievements in studying after they enter their desired schools (Jeon, 2004). However, many foreigners, who finish a language course for the short-term, and need to start university study, cannot properly catch up with university classes requiring expertise with the vocabulary and grammar levels learned during the language course. Therefore, reading education, centered on a strategy to understand university textbooks regarded as top level reading texts to the foreigners, is necessary (Kim and Shin, 2015). This study carried out an experiment from a perspective that quantitative data on the readers of the main player of reading education and teaching materials need to be secured to back up the need for reading education for university study learners, and scientifically approach educational design. Namely, this study grasped the difficulty level of reading through the measurement of cognitive loads indicated in the reading activity of each text by dividing the difficulty of a teaching material (book) into eight levels, and the main player of reading into Koreans and foreigners. Method: To identify cognitive loads indicated upon reading Korean texts with care by Koreans and foreigners, this study recruited 16 participants (eight Koreans and eight foreigners). The foreigners were limited to the language course students studying the intermediate level Korean course at university-affiliated language institutions within Seoul Metropolitan Area. To identify cognitive load, as they read a text by level selected from the Korean books (difficulty: eight levels) published by King Sejong Institute (Sejonghakdang.org), the EEG sensor was attached to the frontal love (Fz) and occipital lobe (Oz). After the experiment, this study carried out a questionnaire survey to measure subjective evaluation, and identified the comprehension and difficulty on grammar and words. To find out the effects on schema that may affect text comprehension, this study controlled the Korean texts, and measured EEG and subjective satisfaction. Results: To identify brain's cognitive load, beta band was extracted. As a result, interactions (Fz: p =0.48; Oz: p =0.00) were revealed according to Koreans and foreigners, and difficulty of the text. The cognitive loads of Koreans, the readers whose mother tongue is Korean, were lower in reading Korean texts than those of the foreigners, and the foreigners' cognitive loads became higher gradually according to the difficulty of the texts. From the text four, which is intermediate level in difficulty, remarkable differences started to appear in comparison of the Koreans and foreigners in the beginner's level text. In the subjective evaluation, interactions were revealed according to the Koreans and foreigners and text difficulty (p =0.00), and satisfaction was lower, as the difficulty of the text became higher. Conclusion: When there was background knowledge in reading, namely schema was formed, the comprehension and satisfaction of the texts were higher, although higher levels of vocabulary and grammar were included in the texts than those of the readers. In the case of a text in which the difficulty of grammar was felt high in the subjective evaluation, foreigners' cognitive loads were also high, which shows the result of the loads' going up higher in proportion to the increase of difficulty. This means that the grammar factor functions as a stress factor to the foreigners' reading comprehension. Application: This study quantitatively evaluated the cognitive loads of Koreans and foreigners through EEG, based on readers and the text difficulty, when they read Korean texts. The results of this study can be used for making Korean teaching materials or Korean education content and topic selection for foreigners. If research scope is expanded to reading process using an eye-tracker, the reading education program and evaluation method for foreigners can be developed on the basis of quantitative values.

• 대한간호
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• 제31권4호
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• pp.77-99
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• 1992

The study was carried out at W. hospital, an affiliated hospital of Y university, involved a total of 163 patients who were discharged from the hospital between May 1990 und March 199J. Data collection was twice, just prior to discharge and a minimum of three months post discharge. Thirty patients who lived within a hour travel time of the hospital received home care during the three months post discharge. Nursing diagnoses and nursing interventions For these patients were analyzed in this study. The results of the study are summarized as follows : 1. Discharge needs for the subjects of the study were analyzed using Gordon's eleven Functional categories and it was found that 48.3% of the total sample had identified nursing needs. Of these, the needs most frequently identified were in the categories of sexuality, 79.3 %, health perception, 68.2 % self concept, 62.5 %, and sleep and rest 62.5 %. Looking ut j he nursing diagnosis that were made for the 30 patients receiving home care, the following diagnoses were the most frequently given; alteration in sexual pattern 79.3%, alterations in health maintenance, 72.6%, alteration in comfort, 68.0%, depression, 64.0%, noncompliance with diet therapy, 6.3.7%, alteration in self concept, 55.6%, and alteration in sleep pattern, 53%. 2. In looking at the effects of home nursing care as demonstrated by changes in the functional categories over the three month period, it was Found that of the 11 functional categories, the need level for health perception, nutrition, activity and self concept decreased slightly over the three month period. On the average sleep patterns improved, but restfulness was slightly less and bowel elimination patterns improved but satisfaction with urinary elimination was slightly less. On the other hand, role enactment, sexuality, stress management and spirituality decreased slightly. The only results that were statistically significant at the 0.05 level were improvement. in digestion and decrease in pain. No statistically significant changes were found in ability related to ADL, the total ADL Score at discharge was $19.78{\pm}8.234, and after 3 months $19.01{\pm}8.12$. Considering that a majority of the patients were over 60 years of age and that many had brain or spinal cord injuries, the fact that their ADL ability did nor deteriorate after discharge can be interpreted as related to a positive impact by the home health care nurses. Similarly there was a slight be not statistically significant decrease in the quality of life scores between the two lest times(l47.83 at discharge and 113.02 at the three month period). Again, when the chronic nature of thee problems facing these patients is considered this maintenance of quality of life can be interpreted as a positive impact by the home health care nurses. 3. One of the home care nursing activities was diagnosis. For this activity it was found that for nine functional health categories(sexuality and spirituality excepted) there were 20 nursing diagnoses. The most frequent were noncompliance, alteration in skin integrity both actual and potential, and impaired physical mobility in that order. 4. Delivery of home health care by the home health nurses included the following nursing activities; assessment, patient education, demonstration of care activities, counselling, direct care to the patient and referrals. Direct care included changing dressings, bladder irrigations, changing Foley catheters, measurement of residual urine, perineal care, position change, back care, oral hygiene, exercise and massage of motion exercises, cleansing enemas, tracheostomy suctioning and tracheostomy care, care of dentures, applications of heat and other similar nursing activities. In conclusion almost 50% of (he sample indicated a need for continued nursing care at the time of discharge and for the patients in the sample who received home care there was a slight decrease in nursing needs but while the patients had chronic and debilitation problems there was ill decrease in ADL abilities or in quality of life. Further study needs Lo be done La increase the reliability and validity of the tool that was used to measure home health care needs. It is also recommended that study by done using a randomized sampling with a control group to compare patients who receive home care with those who do not.